AUTHOR Peace Corps, Washington, DC. Information Collection SPONS AGENCY Agricultural Skills

DOCUMENT RESUME

ED 241 773 CE 038 577

AUTHOR Leonard, David TITLE Tradition5i1 Field Crops. Appropriate Technologies for Development. INSTITUTION Peace Corps, Washington, DC. Information Collection and Exchange Div. SPONS AGENCY Peace Corps, Washington, D.C. PUB DATE Dec 81 CONTRACT 79-043-0129 NOTE 398p. PUB TYPE Guides Classroom Use 7 Guides (For Teachers) (052) EDRS PRICE MF01/PC16 Plus Postage. DESCRIPTORS *Agricultural Education; *Agricultural Production; Agricultural Skills; Agronomy; Annotated Bibliographies; Developing Nations; *Extension Agents; Extension Education; Fertilizers; *Field Crops; Guidelines; Harvesting; Herbicides; Horticulture; Land Use; Measurement; Pesticides; Pests;"Postsecondary Education; *Rural Development; Rural Education; Soil Conservation; Soil Science; Vocational Education; *Volunteers; Volunteer Training

ABSTRACT I This manual, primarily designed to help Peace Corps volunteers develop and strengthen their agricultural skills, deals with traditional field crops. The focus of the manual is on surveying and interpreting local agricultural environment and individual farm units, developing agricultural extension techniques and practices, and providing basic hands-on and technical skills for extension workers in.operations from farm land preparation through harvest. Covered in the individual chapters of the guide are the agricultural environment; reference crops; planning and preparation; soil fertility and management; pest and disease control; and harvesting,

% drying, and storage of crops. Appendixes to the manual include a list

. of common units of measurement and conversion; guidelines for conducting field trial result tests and demonstration plots, structural analysis, and soil samples; directions for using pesticides and herbicides; suggestions for troubleshooting common crop problems; lists of hunger signs in reference crops; and a discussion of planting skills for field extension workers. Concluding the manual are a glossary, bibliography, and list of references. (MN)

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Peace Corps 3 Traditional Field Crops

Written by: David Leonard

Edited by: Marilyn Chakroff Nancy Dybus

Illustrated by: Marilyn Kaufman

This publication was produced for Peace Corps by the TransCentury Corporation, Washington, D.C.

Peace Corps Information Collection & Exchange Manual No.M-13 December 1991 September 1982 TRADITIONAL FIELD CROPS December 1981

Prepared for Peace Corps by the TransCentury Corporation under Contract No. 79-043-0129

Available through Peace Corps, ICE 806 Connecticut Avenue, N.W. Washington, D.C. 20525

>. 5 About This Manual

The Trhditional Field Crops and technical skills,for exten- manual is designed as a learning sion workers in operations from farm land preparation tool and on-the-job reference for through harvest, including Peace Corps Volunteers involved in some routine troubleshooting. small farmer crop improvement pro- To do this, the manual programs in maize, sorghum, millet. pea- vides a summary of current crop pro- nuts, beans and cowpeas. Although duction recommendations under vary- written to be readily understood by ing conditions of climate, soils, non-specialists, the manual contzins management ability, and available much information useful to trained capital; identifies useful field agriculturalists and to planners references and other technical and trainers. resources, including information on Primarily designed to help improvements in equipment for small A Volunteers develop and strengthen farmer row crop production; and the agricultural skills they need reviews recent research advances and for successful work with the target extension efforts in target crop crops, this manual focuses on the yield improvement with special empha- following areas: sis on the role of international Surveying and interpreting crop institutes. Scientific names the local agricultural environment and individual farm are used along with common names to units avoid confusion, as one common name Developing agricultural exten- may refer to a number of different sion techniques and practices species. Providing basic "hands-on"

4 About the Author

David Leonard has been associated with the Peace Corps off and on for the past eighteen years. Originally a B.A. generalist (his- dr tory), he served as an agriculture extension Volunteer in Guatemala from 1963-65 and then went on to get a Master of Agriculture degree in agronomy from Oregon State in 1967. Since then, he has been an agriculture trainer for 35 groups of Peace Corps Volunteers bound for Latin America, Africa, and Asia.. He also grew maize, potatoes and peanuts for three years on a 120-hectare farm in Australia.

iii 7 I

Acknowledgments . 1 would like to express special thanks to John Guy Smith of Washington, D.C., for assistance in planning this manual and for permis- sion to use materials from several' of his publications. No one better understands the realities of small J 'farrier agriculture and the deveLop- ment and introduction of improved farming practices. Also, thanks are due to Trans- . Century's Paul Chakroff, Marilyn Chakroff and Nancy Dybus for their editing assistance; to Marilyn Kauf- man for her fine illustrations; and to Cade Ware for his excellent typ-

ing and layout of the final document. .1

1 I

v . C

Table of Contents

Page

About this Manual i About the Author iii

Acknowledgments V Table of Contents vii 4

1. Introduction 1

2. The Agricultural Environment 9

3. The Reference Crops 35 4.Planning and Preparation 91

5. Soil Fertility and Management 137 6. Pest and DIsease Control 177

7. Harvesting, Drying and Storage 269

Appendices A. Common Unitsof Measure and Conversion 299

B. How to Conduct a Result Test (Field Trial) 301 C. How to Conduct a Result Demonstration (Demonstra on Plot) 307

D. How to Conduct an Elementary Statistical Analys s 311

E. How to Convert Small Plot Yields 315 F. How to Take Soil Samples 317

G. Hunger Signs in the Reference Crops 321

'H. Miscellaneous Pulses 327

I. Troubleshooting Common Crop Problems 333

3. Guidelines for Using Pesticides 337

K. Guidelines for Applying Herbicides with Sprayers 361

L. Important Planting Skills for Field Extension Workers 365

vii . Page.

Glossary 373 Bibliography 375 References 379 Sources of-Illustrations .381 Index 383

viii 10 .

0 . e

-, . 1. Introduction

4.-

1 From 1961 to 1975, total food inequitably amongcountries, different income groups., and production in developing countries even wi.:hin the family. increased about 47 percent. This Since the quantity and quality- of food intake is strongly seemingly impressive gain was ,, linked to income level, r reduced to only 10 percent in terms increases in per person food S production will have little of food production per person 4 effect on hunger and malnutri- because of rapid population growth tion without a large rise in the incomes of the world's rates. In mdse than half of the poor. developing nations, per person -o Postharvest food losses of cereal grain production was lesi in cereals and legumes (dry beans, peanuts, etc.) during proces- 1979 than in 1970. Presently, some sing and storage are conserva- two-thirds of all people in the tively estimated to be 10 per- ° cent on a world basis, but 41 developing countries are considered losses of 20 percent are com- undernourished.* mon in developing cou tries.

.t. Current world food supplies Looking to uture, ere a compared with dietary requirements is little reason for optim A 1974 show only a minor deficit on paper, UN study predicted that in the next but the reality is far more serious, 30 years, human population will for two reasons: increase by26 percent in the developing ,Food supplies are distributed countries, 62 percent, and 119 percent in the developing nations. The study * Population and400d data are concluded that if current food pro- based on figuties from the. Food and duction trends continue in develop- AgriculturalOrganization (FAO) of . the United Nations (UN). ing countries, they will need to

41 (- .

increase their. grain imports fivA- ber of important characteristics: fold between 1970 and 1985. Aside Most small farmers operate from the problem of financing such as independent economic units, either as independent propri- imports, it'is very questionable etors or under a rental whether the ma,lqr grain exporters arrangement allowing them to make production decisions. can meet these needs. In some cases,. however, It is not likely that develor- individual decision-making may be subject to tribal or ing countries can increase food pro- village controls, or :duction rapidly enough during this restricted by insecure xenaqcy. Since they have a small amount decade to achieve self- sufficiency. of land and capital, they However, the food deficiency can be depend mainly on the family labor supply. narrowed if these countries ' The small-scale farmer is less strengthen their recent interest in likely than large-scale far-- crop improvement practices and intro- mers to use capital,for commercial inputs like fertiliz- ductionof new techniques to both ers, pesticides, and equipment. small- and !arge-scale farmers. 6 The small farmer tends to use credit for consumption needs rather than fn'r purchasing farming inputs. 4 CoMpared to. larger farmers, .The Small-Scale small,farmers have limited access to important production factors associated with agri- . ,Farmerand . cultural development such as Agricultural agricultural credit and supplies, adapted technology, Development technical assistance, market " intermatkon, roads, and trans- nor':. ...

, The great majority of'farmers N.' -1 in developing countries operate on a I small scale. Despite much local and regional diversity, they shame a num- 0

., by adopting appropriate improved pro- Assisting Small duction practices. "Appropriate" Farmgrs. means in harmony with the environment and the cultural and economic situation of the farmer. "Improved" refers to the use of non-traditional inputs like fertilizers, agricultural chemicals, new equipment In the developing world, most suited to small-scale farming, and

small-sealefarmers with whom the technical advisory services. It extension worker is in contact are does not imply the total abandonment farmers in transition from tradi- of traditional growing practices but tional.to improved production prac- rather the incorporation of suitable 6 tices. They are aware of outside new elements. inputs liki fertilizers, insecti- Most small-scale farmers will cies, and vaccines for livestock and benefit by participating in agricul- may actually be using one or more of tural development programs.. Since these, though often in a haphazard nearly all.of them want to increase banner.. Although tileir first pro- their yields and incomes, they will

duction priority is usually subsis- adopt new techniques--if these O ience, there is a strong motivation offer a reasonable assurance, of a to produce a marketable or exchange- meaningful return without excessive : able surplus once the family food risk and the necessary inputs are needs are met. available.* Much of the solution to hun- Until fairly recently? yield- ger and rural poverty in thedevelop-, improVing technologywas usually ing countries hinges on the small developed with little regard to farmer's ability to increase his or the realities of the small farmer's

' her returns from traditional crops 1-titert-surprts-i-ny-

(

O r

that these so-called "improved" oped countries, probably because land practices often encountered a cool and machinery are more expensive than response.t Crop production research . labor in mostdeveloping countries. and extension are becoming more The sub - family farm is too attuned to the small farmer's needs, small to effectively employ the and there are numerous examples of equivalent of two adults.and a team successful yield-improving programs of oxen. Unfortunately, in countries involving small farmers throughout like Guatemala, El Salvador and Peru, the developing countries. up to 80-90 percent of the total- farm units are classified as sub- family. The sub-family farm is too The Small Farm As a Viable small to become economically success- Economic Unit ful no matter how much improved technology is used. In this case, Whtn yield-improving prSetices increased size is vital to produc- are used in developing countries, tion. competitively low production costs can be realized over a wide range of farm sizes. Increasing the size of the farm alone is usually not

the answer to production problems . for all small farms, although it can be an important factor for some. There are basically two types of small farm. One is the family- size farm, which can gainfully employ the equivalent of two to four adults and am of oxen. This type of far much smaller in size and capital than its equivalent in the devel-

4 14 The Availability erable retraining of the Of Improved farmer. Production Practices the potential gains exceed the added costs by at least two to one. (This is the cost/ benefit ratio.)

Since the 1960s, there has the commercial inputs and associated services required been a growing effort on the part of for the practice are readily national and international crop obtainable on reasonable terms. research organizati s to develop fea- The pay-af from the new prac- sible yield-improvi g practices for tice occurs in the same crop the reference crops included in this cycle in which it is applied. manual. This is a long, ongoing pro- The costs of the new practice are within the farmer's means. cess, but for many farming regions This usually implies access in developing countries there isnow to credit. a group of improved practices that All of these conditions are will provide significant increases seldom fully met in small farmer agri- in both yields and returns over tra- culture in a developing country. ditional methods. These develop- Nonetheless, with a good extension ments are the small farmers' best service and a well-developed "pack- hope for increasing yields and age of practices", agricultural exten- returns so that they can remain (or sion workers can improve crop yields become) competitive economically and on small farms dramatically. improve their standard of living. The ideal conditions for promoting improved crop production practices among small farmers would ensure that: the new practice does not increase farmer risks, d art radically_from current_ practices, or require consid-

.41 5 a package approach. However, there The "Package' are possible disadvantages; Approach to If the package fails, farmers may conclude that all of the Improving Crop individual practices are Yields unproductive. More adaptive research and extensive local testing are required to develop a proven In most cases, low crop package for an area. yields are caused by the simultane- The package may favor the ous presence of several limiting fac- larger farmers who have easier access to credit for buying tors, rather than one single obstacle. the added inputs. When a specially developed and Unavailability of a component adapted "package" of improved prac- input or its faulty application may make the entire pack- tices is applied to overcome these age fail. multiple barriers, the results are It should be stressed that a Often much more impressive than package does not always have to those obtained from a single factor involve considerable use of commer- approach. A crop "package" consists cial inputs. In fact, an extension of a combination of several locally program can focus initially on proven new practices. (Few packages improvement of basic management prac- are readily transferable without tices that requirelittle or no local testing and modification.) investment such as weeding, land pre- Most include several of the follow- paration, changes in plant popula- ing; an improved variety, fertilizer, tion and spacing, seed selection, improved control of weeds pests, and timeliness of crop operations. and diseases, improvements in land This helps assure that small farmers preparation, water management, har- benefit as least as much as larger vesting, and storage. ones, especially in those regions The likelihood of a positive where agricultural credit is poorly tUtpodgE-is Krtatly-increased -using-----developed.

6 and an ability to adjust recommenda- The Role of the tions for variations in local soils, Extension Worker climate, management, and capital. This manual provides most of the information extension workers need to work with the six reference To work with small farmers to crops. In promoting any crop improve- improve-ylelds-of the six reference Mentpractice, however, it is very crops (maize, sorghum, millet, pea- important to work with the local. farm- nuts, cowpeas, and beans), extension ers, extension service, universities, workers need both agricultural and and national and international agri- extension skills. The general agricultural research institutions. cultural skills required by exten- These individuals and organizations sion workers who will be involved in are much more familiar with the pre- crop improvement projects as intet- vailing local environmental, mediaries with a limited advisory economio, social and cultural condi- role include: tions and should be consulted first understanding the need for before attempting any crop improve- crop improvement programs went program. interpreting the agricultural environment knowledge of the reference crop characteristics knowledge of crop improvement practices understanding of reference crop management principles. Extension workers also will need to have an appropriate level of "hands-on" and technical skills relevant to the reference crops,

17 2. The Agricultural Environment

The purpose of this chap*r is I' to identify how extension workers can The Natural survey and interpret important fea- Environment tures of the local agricultural environment and the individual farm units which are a part of it.This The natural environment con- is vital to effective extension sists of the climate and weather, the since it enables workers to fully land and soils, and the ecology (the comprehend the area's farming sys- interaction among crops, weeds, tems and practices. insects, animals, diseases, and peo- The local agricultural envi- ple). ronment is made of up those factors Weather refers to the daily which influence an area's agricul- changes in temperature, rainfall, ture. The most important of these sunlight, humidity, wind and baromet- are the natural (physical) environ- ric pressure. Climate is the typi- ment and the infrastructure. cal weather pattern for a given locality over a period of many years. To quote one definition, people build fireplaces because of the climate, and they light fires in the fireplaces because of the weather.

9 18 ;he climate and weather factors that Regional and yearly variations in solar radiation have the greatest influence on crop production are solar radiation (sun- Unlike the temperate zone lati- light and temperature), rainfall, tudes, the region between the Tropic humidity, and wind. of Cancer (23.5°N) and the Tropic of Capricorn*(23.5°S) has relatively little seasonal variation in solar Solar Radiation radiation, since the sun remains fairly high in the sky all year long. Solar radiation markedly influ- Measurements above cloud level show an ences crop growth in several ways: annual variation in solar radiation It provides the light energy of just 13 percent at the equator needed for photosynthesis, the fundamental process by versus 300 percent at a latitude of which plants manufacture 40°. However, this suppos'ed advan- sugars for use in growth and tage of the tropics may In some food production. Sugars are made by this process in the cases be largely offset by cloudi- green cells of plants when ness, which can be excessive in' carbon dioxide from the air combines with water from the the higher rainfall zones, particu- soil using sunlight and chlo- / rophyll (the green pigMent in larly near the equator (cloudiness plants) as catalysts. can reduce solar radiation by 14-80 The daily duration of sun- percent depending on depth and light (daylength) and its yearly' variation greatly extent of the cloud cover). For affect time of flowering and example, due to heavy cloud cover, length of growing period in some crops. the equatorial Amazon Basin receives Solar radiation is the pri- only about as much total yearly mary determinant of outside solar energy at ground level as the temperature, which strongly influences crop growth rate Great Lakes region of the U.S. and range of adaption.

10 19. Table 1 Day length Length of Day in Various Northern Latitudes

Month Equator 20° 40° The length of time from plant Dec. 12:07 9:20 emergence to flowering as well as 10:56 Mar. 12:07 12:00 11:53 the actual date of flowering can be Jun. 12:07 13:20 15:00 Sep. 12:07 12:17 12:31 strongly affected by daylength in the case of some crops. Among the reference crops, soybeans and the Temperature photosensitive varieties of millet and sorghum are the most affected. Temperature is the major fac- Maize is less influenced by tor controlling a crop's growth daylength unless a variety is moved rate and range of adaption. Each to a latitude where daylength is crop has its own optimum tempera- markedly different from that of its ture for growth, plus a maximum point of origin (see Chapter 3). and minimum for normal development Daylength is usually not a critical and survival. Even varieties factor with peanuts, beans and cow- within a crop differ somewhat in peas. their temperature tolerance. Exces- As shown by the table below, sively high daytime temperatures both latitude and season influence can adversely affect growth and daylength. Note that the annual yields by causing pollen sterility variation in daylength markedly and blossom drop. in addition, the decreases as the equator is hot nights common in the tropics approached. can reduce crop yields. This is because plants manufacture sugars for growth and food production by the daytime process of photosynthesis, but "burn up" some of this at night through the process of

11 20 respiration. Since high nighttime more distinct micro- climates. temperatures increase the respiral Cloud cover has a definite buffering effect on diurnal tion rate, they can cut down on the (daily) temperature variation. crop's net growth. It will lower the daytime high Several factors affect an but raise the nighttime low. Humidity exerts an effect area's temperature' pattern: similar to cloud cover on tem- Latitude--Seasonal temperature perature.. Humid air takes variations are pronounced in longer to heat up and cool off the temperate zone where solar and therefore is subject to radiation and daylength fluc- considerably less daily tem- tuate considerably over the perature variation than dry year. In the tropics, this air. Maximum shade tempera- seasonal temperature differ- ture rarely exceeds 38°C under ence is much smaller. Night- high humidity, while maximums time lows are seldom below of 54°C are possible under dry 10-30°C near sea level and are conditions. usually above 18°C. Seasonal variations become more pro- Rainfall nounced as the distance from the equator increases. Elevation--Temperature drops In dryland (non-irrigated) about 0.65°C for each 100- areas of the tropics with year-round meter rise in elevation. This greatly affects a crop's growing temperatures, rainfall is the length of growing period as major environmental factor that deter well as its adaptation to the area. For example, at sea mines which crops can be grown, when level in Guatemala, maize they are planted, and what they will matures in three to four months and the climate is too yield. Rainfall varies greatly from hot for potatoes; however, place to place (often within surpris-, about 50 km away in the high- tends (above 1500 m), maize ingly short distances), especially takes five to ten months to around mountainous or hilly terrain. mature and potatoes thrive. The dryland farmer is keenly aware of e 'Topography, or the shape of the land surface, can cause his area's seasonal rainfall distribu- diffences in local weather tion. This includes deviations from and clime (micro-climates). A work areS\may have two or the norm' cycle such as early or late

12 rains, or unseasonable droughts. is shorter, and soil moisture is usu- Too much rain, which can drown out ally adequate for only an 80-90 day the crop, delay harvest, and accel- crop. On the other hand, Samaru's erate soil erosion, can be just as equal rainfall is spread out over serious as too little. It may be five months in a uni-modal pattern, too wet for plowing one day, yet providing for a single maize crop not too dry the following week for good subject to moisture stress. seed germination. From the example it is appar- When gathering rainfall data ent that annual rainfall averages for an area, one should keep in alone are not a dependable gauge of mind that annual rainfall averages the rainfall in an area. The same have little meaning. Seasonal dis- goes for seasonal rainfall distribu- tribution and reliability are far tion. Although it gives a good gen- more important in terms of crop pro- eral indication of the amount of duction. moisture available for crop produc- For example, Ibadan Nigeria, tion, it does not tell the whole is located in the transition zone story. The amount of rainfall that between the humid and semi-humid actually ends up stored in the soil tropics and receives about the same of a farmer's field for crop use annual rainfall (1140 mm) as Samaru depends on other factors Apch as Nigeria, which is located to the water run-off and evaporation from north in the savanna zone. Ibadan's the soil surface, and the soil's rainfall is spread out over nine texture and depth. months from March to November in a When interpreting the rain- bi-modal pattern (i.e., two rainy fall pattern of a work area, it is seasons with a drier period in good to remember that averages are between). 'The first season is long somewhat misleading. Variations to enough for a 120-day maize crop, the average can be expected even although there is some periodic though the general seasonal distri- moisture stress. The second season bution curve usually maintains a

13 22 consistent shape (Figure 1). Crop Calendar,_ Managua Area of Nicaraua .Cropping cycles and how they relate to the rainfall pattern: Long season maize Cropping cycles are deter- 4 Short season mined by using the cropping calendar maize N 4 1- I planting and harvest dates for crops Beans involved), and are closely tied to Improved the seasonal-rainfall distribution. sorghum F -11- - 4 This can be seen by comparing the Native photosensitive sorghum'--- -1 cropping calendar in the next column J with the rainfall chart in Figure 1. F MA MJ JA SO ND J

A primary source of rainfall 4 information in a given area is the local farmer. AlthOugh official weather station rainfall data is handy Figure 1 Monthly Rainfall Pattern, Managua, Nicaragua, 1958-67

(500 mm)

`(400 mm)

'(300 mm) *

(200 mm)

(100 mm) +.. * . *

J F M A M J A S N D' r Wettest year, 1958 Annualtotal: 1437 mm Driest year, 1965 Annualtotals: 757 trim Average, 1058-67 Annualaverage: 1909 mm Highest monthly rainfall between 1958-1967 *** ******* Lowest monthly rainfall between 1958-1967 +++++++++++

14 23 to have if it is reliable and repre- sorghum and millet are most pone to sentative, it is not.essential. damage from heavy rain. Hot, dry Most of the information needed about winds can markedly increase the water rainfall distribuirion can be found needs of crops. The frequency of high by talking to experienced local larm- winds is also a factor that warrants ers. investigation when surveying a work area's climate. Humidity Topography

Relative humidity affects crop production in several ways: The shape of the land surface Daily temperature variation influences agriculture by causing is greater under low humidity; local modifications in climate and high humidity exerts a buffering effect on temperature. weather and often is the major factor High humidity favori the that determines the suitability of development and spread of a land for various types of farming. A number of fungal and bacterial diseases (seefthe disease vork area may include several topo- section in Chapter 6). graphic features such as mountains, The rate at which crops use hills and valleys. Individual farms, water is highest under hot, dry conditions, and ).ow- too, often have significant topo- est when it is very humid. graphic variations that affect crop productiOn. Mountaini and hills can Wind and Storm greatly alter rainfall, and it is Patterns not uncommon to find, a drier, irri- gatedvalley on one side of a moun- High winds adbestated with tain range and .a wetter, rainfed thunderstorms, hurricanes, and Lorna-,valley on the other side. Cold air dos can severely damage crops. usually settles in valleys, making Among the reference crops, maize, them considerably cooler than the

15 24" surrounding slopes. Steep slopes varying proportions of air and water drain rapidly, but are very suscep- depending on how wet or dry the soil

tible to erosion and drought, while is. The other 50 percent of the flat or sunken areas often have :'.rain - volume is made up of mineral parti- age problems. Slopes angled toward cles and humus. Most mineral soils the sun are warmer and drier than contain about two to six percent humus by those angled away from it. weight in the topsoil. Organic song like pests are formed in marshes, bogs and swamps, and contain 30-100 Soils percent humus. Climate, type of parent rock, After climate and weather, topography, vegetation, management soil type is the most important and time.all influence soil formation local physical feature affecting and interact in countless patterns to cropping potential and management produce a surprising variety of :Inns, practices. Most soils have evolved even within a small area. In fact, slowly over many centuries from it is -.not uncommon to find two or weathering (decomposition) of under- three different soils on one small lying rock material and plant mat- farm that differ widely in management ter. Some soils are formed from problems and yield potential.

. deposits laid down by rivers and Important Soil Characteristics seas (alluvial soils) or by wind There are seven major charac- (loess soils). teristics that determine a soil's Soils have four basic compo- management requirements and produc- nents: air, water, mineralparticles tive potential: texture, tilth (phy- (sand, silt and clay), and humus sical condition), water-holding capa- (decomposed organic matter).A typ- city, drainage, depth, slope, and pH. ical sample of topsoil (the darker- Texture refers to the relative amounts of sand, silt colored top layer) contains about and clay in the soil, 50 percent pore space filled with

25 r

Tilth refers to the soil's Ecology physical condition and capa- bility ofbeing worked. For pur purposes, ecology Water-holding capacity refers to the ability of the soil to refers to the presence of, and inter-

retain water in its spaces. * action among, the reference crops, Drainage refers to the soil's weeds, insects, diseases,animals ability to get rid of excess uR water and affects the acces- (humans, wildlife and livestock), sibility of oxygen to roots. and the environment in general. Depth is the depth of the Agriculture is a perpetual contest' soil to bedrock and the effective soil depth is the depfb with nature and,farmers have devel- to which plant roots campene- oped many preventative' nd control, trate. measures, as well as special crop- Slope is the inclination of the land surface, usually meas- ping systems, to give agriculture ured id percentage (i.e., 'num- the advantage over natural succession. ber of meters change in elevation per 100 m horizontal dis- Each area will'have its own combina- tance). tion of weeds, insects, diseases, and's A is a measure of the acidity a wildlife (including rats and grain- or alkalinity of the soil on a scale oT 0 to 14. eating birds) that affect crop pro- These characteristiCs are dis- duction. Identifying these and cussed in detail in Soils, Crops and learning how farthers cope with them Fertilizer Use, U.-6. Peace Corps. is crucial to understanding and deal- Appropriate Technologies.for Develop- ing with the agricultural environment Manual. #8, Parts I & II,. by D. ment. Leonard, 1969, and Crop Production The effect of peOple and agriculture on the overall environment Handbook, U.S. Peace Corps Appropri . ate Technologies for DevelopmentMan- Modern technology; land short- ual #6, Unit I, 1969. ages, and increasing populations hale increased agriculture's ability and

tgt need io "beat lack" and manipulate

'nature. Often little thought is

17 26 given to the possible environmental Local Farming consequences of agricultural develop- Practices and Systems went. Potential ecological impacts 'of agricultural projects include:* Deforestation Farming practices include: Soil erosion Landpreparation-4illage Desertification methods, type of seedbed, and Laterization erosion control methods- Salinization Planting -- method, plant population and spacing, choice of Agrochemical poisoning of soil, variety water, animals anZ people Soil amendments--kind, amount, Flooding. timitg, placement of chemical or organic fertilizers and liming materials

0 Controlof weeds, insects, diseases, birds, rodents and The Infrastructure nematodes (tiny, parasitic roundworms that feed on plant roots)

The infrastructure, which Special peictices such as irrigation or "hiding up" refers to the installations, facili- maize

ties, goods, and services 'at -- Sarvest and storage methods. encourage agricultural production, . consistsof these elements: The terms "cropping system" Local farming practices not only refers to the overall crop- . The physical infrastructure Ping calendar (planting and.harvest

' Land distribution and tenure dates for the crops involved) but . Agricultural labor supply more specifically to the actual crop

. Incentives to farmers. se uences and associations involved, namely: * For further information, refer to Environmentally Sound Small Scale Monoci Lure versuabcrop rota- Agriculture Projects, VITA, 1979. tion--Monoculture is the

-27 repetitive growing of the same The Physical crop on the same land year Infrastructure after year. Crop rotation is the repetitive growing of an orderly succession of.crops The physical infrastructure (or crops and fallow) on the same land. One crop rotation refers to the physical installations cycle often takes several and facilities that encourage agri- growing seasons to complete (for example, maize the first cultural production such as transpor- two years, followed by beans tation (farm-to-market roads, rail- the third and cotton the fourth). roads), communications, storage and Multiple 04ping7-There are market facilities, public farm works two types of multiple cropping. (regional irrigation, drainage, and One is sequential cropping, which means growing two or flood control systems), and improve- more crops in succession on . ments to the farm (fencing, wells, the same field per year or per growing season. The other is windbreaks, irrigation and drainage intercroppink, which is the systems, etc:). All of these are most common definition of multiple crqpping and involves important, but adequate and reason- the growing of two or more ably priced transport is especially crops at the same time on the same field. See Chapter 4 critical since agriculture is a busi- for details on the different ness that involves handling bulky types of intercropping. materials. A farmer's distance from Due to differences in soils, the road network is eften the prime

. . climate, management ability, avail- fectdr determining whether or not he able capital, and attitudes, impor- or she can profitably use fertilizer tant differences in farming practices or move hii or her surplus crops to and systems may be found within a market. particular area.

19 28 Land Distribution tries have a generally high rate of And Tenure agricultural underemployment, except during a few peak periods such as In a settled area, all the planting at the start of the rains agricultural land may be occupied. or wee 1ng time, if mechanical culti- The land distribution and tenure situ-vation is not used. At these times, ation in an area thus has enormous the scarcity of labor.Can become the social and economic consequences and most critical factor limiting produc- greatly affects farmer incentives. tion, and labor productivity assumes The two most important issues in this an unusual importance. 4. regard are: Who-occupies the land and on Incentives for what terms do they use it or FartnerS allow others to use itV What is the ratio between the number of people dependent These can be very broadly on farming fortheir liveli- interpreted, since they include equi- hood and the amount and kinds of land available? table land tenure and distribution, adequate markets and prices for farm produce, and the existence of a The Agricultural Labor Supply viable improved technology.

The ratio of farmers and farm laborers to the amount and types of Understanding the land provides a good indication of land use intensity. The existence Individual Farm of adequate farm labor for peak per- , Unit iods is another important consideration affecting farm practices and returns. For most of the year, many Each farm has its own unique farming areas in developing coun- characteristics, but those located in

29 the same area usually share enough Natural characteristics such as soil type, slope, soil similarities to allow grouping them depth, drainage, access to into several general types of farm water, etc. unit, such as-subsistence, market- Proximity to the transportation network and other facilities oriented field crop, plantation, etc. such as public irrigation and If an area's environment is fairly drainage systems uniform, only one type of farm unit Location in relation to other farm units may predominate. If it is character- Local name of the farm's loca- ized by irregular topography and lop- tion. sided land distribution, the area may have two or more types of farm Type of Occupancy units. There are eight basic cri teria that can be used to differen- The principal considerations tiate types of farm units: are: Location Who owns the land?

Type of occupancy If not owner-operated, what is - the tenancy arrangepent (i.e., lSize of farm, parcelling, and cash rent, crop share, or work land use potential share) and on what specific iSize of-the farm business terms? How secure is the arrangement? 7ype of farm enterprise If no one has legal title to Production practices the land, is it occupied under Farm improvements squatters' rights that are protected by law? Farm labor supply. Who manages the farm unit and makes the basic decisions? Location

The principal factors here are:

30 Size of Farm Type of Farm Enterprise

Total farm size in terms of local units of measure Some farms are engaged in only Location of farm parcels: If one enterprise such as growing sugar- they are dispersed, how far are they from the farmer's cane, coffee, rice, etc., but this house? type of monoculture is unusual among Actual land use: tillable small farms. More likely, some form versus pasture versus forest; irrigated versus non-irrigated of mixed agriculture will exist. The Characteristics of its soils: main considerations are: local name, color, texture, Relative importance of each depth, drainage, slope, plus enterprise farmer's opinion of them. The yields obtained from each enterprise Size of Farm . The disposal of the products Business from each enterprise (subsistence or cash sale) and where sold Land value of the farm unit -o Crop rotations and associa- Value of other fixed assets tions Amount of operating capital Relationship, between crop and employed per land or livestock livestock production, if any. unit The value of production per land or livestock unit. Production Practices The value of the farm unit compared to its number of workers The specific factors used in

indicates whether it is capital-inten- agricultural development , sive (using machines and money to har- Rate, method, and time of application. vest) or labor-intensive (using human labor to perform farm operations). The value of production per land unit indicates the intensity of land use.

22 .Farm Improvements

Condition of the farm family home (or the farm manager's and farm workers' homes). Presence and condition of fences, wells, irrigation works, field access roads, storage facilities, livestock shelters, corrals, etc.

The Fann Labor Supply

Degree of reliance on the family's own labor force and the composition of that force Degree of dependence on hired labor The seasonal nature of work requirements Use of animal or tractor- drawn equipment.

23.

32 Guidelines for the Orientation of the Extension Wbrker

These guidelines are designed (farmers, etc.) and that from outside or official sources, to help newly assigned agricultural trust the local "grass roots" field workers (AFW) orient them- information until proven otherwise. Local farmers are selves to the local agro-environment the ultimate authorities on and its individual farm units within the local environment. one or two months after arrival in The guidelines that follow are organized mainly by subject when using the guidelines, the area. area but do not have to be keep in mind the following: followed in a set order. You, will be picking up bits and Do not undertake a highly pieces of information from a detailed survey of local single informant that may resources at the start of the deal with a number of areas, assignment unless the host and you will have to put them agency specifically requests into their proper context. it. Such a survey is likely to arouse local suspicions, especially if you are over- zealous or overbearing with your initial contacts. The host agency may provide a basic orientation to the work area, but it may be very limited,. If there are discrepancies between the information gathered from local sources

24 33 Locate Farmers Introductory Get a general idea of how farm rs are distributed geo-

Orientation gra ica . 4( Get a specific idea of where likely clistir farmers-are 44. located (i.e., those with whom your job description This initial phase focuses on deals). the AtogriculturAlenvironment in gen- Locate Other Knowledgeable eral and is designed to help you fam- Individuals. iliarize yourself with it and adjust Agricultural technicians sta- your work schedule and activities to tioned or working in the area, local the seasonal rhythm Of the area's buyers of farm produce, agricultural agriculture. Unless severely limited supply dealers, and truckers are bf your local language ability, you good sources of information. should be able to complete this Select Reliable Local Sources phase in two to four weeks if you At the early stage, your contacts do not have to be completely spend several hours a day talking with local farmers and other sources representative so long as they are of agricultural information through- knowledgeable.The best farmer-inform- out the area. ants are usually among the more progressive farmers. For example, a Establish progressive small farmer will provide Communication more information and insight into small farming operations than a A major part of your time will larger-scale commercial farmer. be spent talking with and listening Likely initial contacts are: your to farmers and other knowledgeable landlord's relatives, the local mayor sources (local residents) who. have OT other local official, the more a vested interest in agriculture. easily accessible and talkative farm;

34 t

ers, or farmers who have worked with Become Familiar extension services for some time. With the Principal e Physical Features Keep a careful record of all initial contacts. How to Interview In order to locate farms, farm- Introducing yourself -- Ideally, ers% agriculttiral suppliers, etc., you should have a third party make the initial contact and you should pinpoint their locations introduction. If this is not with reference to roads and trails possible, be prepared with a practiced explanation of your and dominant topographic features. presence. It is imv)rtant that The principal physical and demo- you emphasize that you are tine learner at this stage. graphic features of the work area Suggested techniques--Allow should also be located and under- the farmer to talk as spon- stood. These include: taneously as possible. Any leading questions almost Topographical features--alti- always get "yes" responses. tude, streams, principal fea- Use a memorized interview tures (landmarks) recognized schedule rather than a writ- locally as reference points, ten one which is likely to valleys, farm and non-farm inhibit responses. Avoid lands over-familiarity. Communications (roads and It is generally not a good trails)--seasonal access, dis- idea to take written notes tances, travel times and modes in front of a farmer, although of travel between points in some cases he may expect Demographic -- locations of com- you (as a "technician") to munities (and their local do so. Some farmers may view names), farmers written notes as having some possible conncection with Infrastructure -- irrigation future tax collections, etc. systems, drainage systems, It's best to wait until an agricultural supply stores, unobtrusive moment such as the schools, extension offices, mid-day break to summarize etc. information in written form. You can make a base reference map yourself which shows these fee- -tures, relying on your own observe-

26 35 tions as well as road maps, geo- You can draw a rainfall.chart, graphic maps, or soil survey/land which is accurate enough for the ini- use maps available from government tial orientation simply by systemat- agencies and international or ically recording farmer's comments regional organizations working in about the seasonal distribution of the area. rainfall; the same can be done for seasonal temperature variation. Climate and weather checklist Become Familiar With Climate and Make tables and/or charts Weather Patterns showing the monthly distribution of raineall using these criteria: Sources of Information Dry to wet scale: (See rainfall section, Chapter,2.) Weather station records- - Obtain all available meterolo- Rainfall frequency: the num- 4 gical data from the official ber of times it normally weather station nearest to rains in a week or month your area of assignment. Its Risk factors associated with orientation value will depend on the station's proximity climate and weather (i.e., droughts, and how well it represents hail, high winds, flooding) can be your area's conditions. established by having farmers recall Relief maps--Altitude is'the main temperature determinant bad crop years over a span of years. in the tropics; remember that Be sure to distinguish weather fac- for every 100 m rise in altitude, average (mean) tempera- tors from,other causes such as ture will drop about 0.65°C. insects and diseases. Local farmers--Official weather data can be valuable, As for temperature, be sure to but it is not essential. record: Information about local climate and weather conditions Monthly temperature averages. can be learned from experi- Periods of significantly high enced local farmers. or low temperatures. Occurrence of first and last killing frosts if applicable.

27 36 Describe the kind and amount Become Familiar of inputs associated with the With Prevailing practice. This includes the Farming Systems amount applied, method and and Practices timing of application, and worker-days of labor. Identify the major crop and livestock enterprises in the work area.' Estimate yields and returns For each of the crop enter- At this stage of the orienta- prises which predominates in the tion, it is not necessary to make a area, indicate the'following and detailed account of costs and returns. note any local vaffations: Seeking such data can arouse local The growing season--Indicate suspicions or fears of future tax the normal growing season and levies. Rough estimates of produc- its variations (early-late), and make a cropping calendar tion costs, and gross and net returns using line bar graphs (see are sufficient. rainfall section, Chapter 2). Record reported yields per Describe production practices - unit of land. --Do not confuse the practices recommended by el.:ten- Record recent prices at nor- sion with those generally mal time of sale. accepted by farmers. Your Multiply recent prices by interest is in the prevailing approximate average yield to practices used by most of the get approximate gross returns. farmers in the area. Make note of any significant dif- Subtract approximate produc- ferences among different tion costs from groia-returns groups of farmers. to obtain approximate net returns. There are two ways Describe the principal land to do this: net return to preparation practices--Specify capital, land, and family the earliest and latest dates labor where the only labor of application and indicate costs you account for are what the practices are called hired labor, or net return to locally. For example, in many land and capital in which areas of Central America, the case an opportunity cost practice of hilling up maize' (exchange value) must be (throwing soil into the row) assigned to family labor and is called "aprogue". subtracted from the gross

,er return. The first_way is the Summarize the easiest. Information Indicate the relative tendencies of production Estimate the percentage of Every area'sagriculture is the crop that is marketed. tuned to a time schedule or seasonal Identify the principal local rhythm to which work schedules and market outlets (buyers). ,activities must be adjusted. Getting Indicate the seasonal movement of production off the oriented in time is vital to effec- farms: is it sold at harvest, tive agricultural extension. some sold at harvest, some held for higher prices, etc.? The best way to do this is to Indicate the seasonal price summarize the initial phase of orien- fluctuations (average over tation by-making graphs and calendar several years). charts that show the area's seasonal . List the outside production inputs which are available locally. ("Avail- rhythm of climate, agriculture, and able" means when needed.) social life. Crop production supplies (give The following graphs, charts, brands, grades, and unit prices): fertilizers, insecti- and observations were made by a group cides, fungicides, herbicides, of Peace Crops Volunteers assigned hand tools, hand- operated equipment, seeds, etc. as rural credit agents in the Paci- Agricultural machinery and- fic region of Niraragua during an equipment (if used): tractors orientation-training. exeTase. The (horsepower and make),implements, irrigation pumps, etc. principles invaved apply worldwide. Services: such as custom mach- Make a generalized climate and weather inery services and rates calendar charged, and professional ser- Chart the normal monthly dis- vices (indicate whether public tribution of rainfall as or private), technical assis- related by farmers using_terms tance and soil testing, etc. Such as. wet, dry, sane rain,

29 38 Frequency of Rainfall

4 times/wk. 3 times/wk.

2 times /wk.' 1 time/wk. 0 times/wk. 3FMAMJJAS0 ND

wettest time, rainfall drops Make a-calenaar of agricultural acti- off, etc. There are three vity. ways to do this,: For each of the major" crop 1. Use the frequency of rain- enterprises. display the fall to measure seasonal dis- length and possible range of tribution (see chart'above). growing season, including likely variations in planting 2. Use a dry-to-wet scale. and harvest times.

3. Measure rainfall, if you (See example at the top of have access to reliable page 31.) meteorological data Indicate the range and fre- Indicate the time for perform-- quency of possible deviations ing critical operations and from normal rainfall patterns relative labor requirements of from information passed on to those operations. you from farmers, or recorded (See example at the bottom of by a weather station. :(See page 31.) 1 chart above.)'

30 39 0 Example: Crop Calendar, Crops and Order of Importancein the Esteli Area of Nicaragua

.7 plant harvest 1. Maize, long season .141111W 2. Bice, dryland 3. Beans ADP- -l=1 4. Improved, non- photosensitive sorghum

M J J A S O N -D J

Example: Distribution of Work and Timiig of PrincipalFarming Operations in the Esteli Area of Nicaragua

Outside help needed

Farm family labor supply adequate

JFIIAMJJ AS ON J

1. Land clearing. 5. First harvest 2. Land preparation 6. Second harvest 3. rrincipal seeding 7. Harvest c. 4. Weeding

31 40 O

Indicate the relative seasonal patterns (the rate at which labor demand, whether there the crop is marketed). are any periods of labor move- Graph the seasonal range of ment into or out of the area. prices. Determine the seasonal demand for.other critical inputs: Hake a calendar of social activity keep in mind an input is not that includes religious holidays and considered critical unless other holidays or seasonally deter- farmerPfeel it is. (For mined social obligations. example, if fertilizer is not generally used, it is not The summary concludes the presently a critical input.) initial,, phase. With a Make a calendar of economic activity good understanding of the local related to agriculture. agricultural environment and farming Indicate relative demand for short-term production credit. practices, you are ready to move on (See example below.) to the next step : ;'orientation to the Indicate seasonal marketing individual farm unit.

Example-: Demand for Production Credit, Branch Office of the National Bank of Nicaragua

Number of 200 Credit Applications per Month 100

JP M A M 3 3 AS ON DJ,

32 f ;41 I Describe the Orientation to the . Annual Agricultural Cycle asTerceiyed Farm Unit. By the Farmer

For each type of farm unit Learning to communicate effec- with which you are likely to work, tively with individual farmers about make an annual diary which indicates: their farm enterprises and their farm Normal operations by months businesses will help move you out of or seasons the questioning stage into a more the decisions which the farmer has to make that are related active role. Expressing an interest to these operations in and being knowledgeable about the The farmer's concerns throughout the year, such as the tim- farm business can be the means as ing of the rains, dry spells, well as the purpose of communicating bird damage to crops, flooding, obtaining inputs, com- with farmers and will definitely pleting operations in time, increase your rapport and credibil- etc. ity with them.

Describe Typical Farm Units

Make a general farm profile which is representative for each of the types of farm unit with which you will be working.--"

33 42 3. An Introduction to the Reference Crops

There are several reasons why the six reference crops -- Cereal Crops Versus maize, grain sorghum, millet, pea- Pulse Crops nuts, field beans, and cowpeas -- are grouped together in one manual. All of the reference crops are row Maize, grain sorghum, and crops (grown in rows) and because millet are known as cereal crops, of this, they share a number of along with rice, wheat, barley, similar production practices. oats, and rye. Their mature, dry Also, in developing nations, two or kernels (seeds) are often called more of the crops are likely to be cereal grains. All cereal crops common to any farming region and belong to the grass family (Grami- are frequently interrelated in neae) which accounts for the major terms of crop rotation and inter- portion of the monocot (Monocoty- cropping (see Chapter 4,page 91). ledonae) division of flowering In addition, all of them are staple (seed-producing) plants. All mono- food crops. The developing coun- cot plants first emerge from the tries are major producers of the soil with one initial leaf called a reference crops, with the exception seed leaf or cotyledon. uf maize.

35 43 (Left) A germinating maize seedling; note that it has only one seed leaf, which makes it a monocot.Monocots emerge through the soil with a spike- like tip. They generally have fewer problems with clods and soil dusting than dicots.

Peanuts, beans, and cowpeas are known as pulse crops, gain legumes or pulses, along with others such as lima beans, soybeans, chickpeas, pigeonpeas, mung beans, and peas. The pulses belong to the

Table 2 World andlRegional Production of the Reference Crops (1977 FAO data) Crop Total World Production Percent of World Production (millions of metric tons) Developing Developed Countries Countries

MAIZE 350.0 32.4 `:\ 67.6 GRAIN SORGHUM 55.4 59.9 40.1 MILLET 42.9 95.1 4.9 PEANUTS (Groundnuts) 17.5 88.2 11.8

FIELD BEANS, COWPEAS 12.9 86.]. 13.9

36 44 (Right) A germinating bean plant; note the two thick cotyledons (seGd leaves) which originally formed the two halves of the seed.

legume family (Leguminosae) whose plants produce their seeds in pods. Some legumes like peanuts and soybeans are also called oilseeds because of their high vegetable oil content. The pulses belong to the other major division of flowering plants called dicots (Dicotykedo- nae). Unlike the monocots, dicot plants first emerge from the soil Nitrogen is the plant nutrient needed in the greatest with two seed leaves. quantity and is also the In addition, the pulses have most costly when purchased as chemical fertilizer. The two outstanding characteristics for Rhizobia live on small farmers and for those who consume amounts of sugars produced by the legume and, in return, them: convert atmospheric nitrogen They contain two to three (ordinarily unavailable to times more protein than plants) into a usable form. cereal grains (see Table 3). This very beneficial process Legumes obtain nitrogen for is called nitrogen fixation. their own needs through a In contrast, cereal grains symbiotic (mutually benef i- and other non-legumes are cial) relationship with totally dependent on nitrogen various species of Rhizobia supplied by the soil or from bacteria that form nodules fertilizer. on the plants' roots (see illustration on page 38).

37 45 The Nutritional Value Of the Reference Crops

The cereal grains, with their high starch content and lower prices, make up a major source of Nitrogen-fixing nodules on the roots of a bean plant. energy (calories) in developing Note that they are attached countries. There, cereal consump7 . to the roots rather than an actual part of them. tion is high enough to contribute a substantial amount of protein to Despite the urgent need to the diets of older children and 'increase both cereal and pulse pro- adults (although still well below duction in the developing countries, quantity and quality requirements). most crop improvement efforts of the Another plus is that cereal grains "Green Revolution" emphasized the contain a numbFr of vitamins and

cereals (see page 294). As minerals, including Vitamin A which a result, pulse yields in the region can be found in the yellow varie- have shown little, if any, increase. ties of maize and sorghum. In some areas, total pulse produc- gained from eating large quantitiei) tion has actually declined in favor of the cereals, their protein

of the cereal grains, even though tent is relatively low (7-14 t . many developing nations suffer from cent) and they are deficient in a chronic protein shortage. Fortu- several amino acids. Infants and nately, this situation is now being children, who have much higher pro- reversed. tein needs per unit oflbody weight

38 46 and smaller stomachs, do notget as All animal proteins (meat, much protein from cerealsas adults. poultry, fish, eggs, milk and Studies have also shown thatsome cheese) are complete proteins (con- reference crops lose vitamins and tain all essential amino acids), protein in substantial amounts with but their high cost puts themout of traditional preparation methods reach of much of the population in (milling, soaking, and drying). developing nations. The pulses have considerably Fortunately, it is possible highrr protein contents than the to satisfy human protein require-

cereal grains (17-30 percent inthe ments without relying solely on ani- reference pulses) and generally mal protein sources. The cereals higher amounts of B vitamins and and pulses, though not completepro- winerals. Unfortunately they also teins in themselves,can balance out may have some deficiencies in amino each other's amino acid deficiencies. acids. Cereals are generally low in the

Table 3 Nutritional Value of the Reference Crops (dry weight* basis)

Crop Percent Protein Calories/100 grams Calories/lb. MAIZE 8-10 355 1600 GRAIN SORGHUM 7-13 350 1600 MILLET (Pearl) 10-13 330 1500 COMMON BEANS 21-23 340 1550 COWPEAS 22-24 340 1550 PEANUTc. (GROUNDNUTS) 28-32 400 1800

39 47 essential amino acid lysine, but number two position after wheat. relatively high in another, methio- Several factors account for the im- nine. The opposite is" true for most portance of maize: of the pulses. If eaten together or Maize, can adapt to a vide within a short time of each other range of temperature, soils and moisture levels and resists and in the right proportion (usually disease and insects. about a 1:2 ratio of pulse to It has a high yield poten- cereal), combinations like maize and tial. beans or. sorghum and chickpeas are It is used for both human complete proteins. In most devel- and animal consumption. oping countries, however, pulses are Types of Maize more expei(sive than the cereal There are five principal grains, which creates difficulties types of maize: in achieving a balanced diet. Dent: The most widely grown type in the U.S. The seed has a cap of soft starch that shrinks and forms a dent at the top of An Introduction to the kernel. Flint: Widely grown in The Individual Latin America, Asia, Africa and Europe. The kernels Crops are hard..and smooth with very little soft starch. It is more resistant to storage insects like wee- Maize vils than dent or floury (Zea mays) maize. Floury: Mainly soft starch and widely grown in the Andean region of South Americt. It is more prone Distribution and Importance to storage insects and In terms of total,world pro- breakage than harder types. duction, maize and rice vie for the

40 48 An ear of maize. Each silk leads to an ovula (potential kernel) on the cob. Varieties vary in length and tightness of husk covering, which determines resistance to insects and moisture-induced molds which may attack the ear in the field.

Pop: Really an extreme provement at the end of this chap- form of flint maize. ter). Sweet: At least twice as Maize Yields high in sugar as ordinary maize and meant to be con- Average yield of shelled sumed in immature form when grain (14 percent moisture) under only about one-third the potential grain yield has varying conditions are shown below. been accumulated. It is Climatic Requirements of Maize more prone to field insect damage, especially on the Rainfall: Non-irrigated ears. (rainfed) maize requires a minimum A potentially very valuable of around 500 mm of rainfall for type called hi- lysine maize with satisfactory yields. Ideally, the more than double the content of bulk of this should fall during the lysine is nearing the mass applica- actual growing season, although deep tion stage, but still has some loamy or clayey soils can store up field and storage problems to over- to 250 mm of pre-season rainfall in come'(see the section on maize im- the'future crop's root zone. Any of

Average Yield of Shelled Grain

lbs./acre kg /hectare_

Top farmers in the U.S. Corn Belt 9,000-12,000+ 10,000-13,500

U.S. Average 5,050 5,700

Average for developed countries 4,200 4,700

Average for LDC's 4.50-1,3t0 500-1,500

Feasible yield for small scale .LDC farmers with 3,500-5,500 4,000-6,000 improved practices

Source: FAp and USDA data, 1977.

51 the following factors will act to Yields are also reduced by excess- increase the moisture needs of maize ively high nighttime temperatures, (and other crops): since they speed up the plant's Long growing periods due to respiration rate and the "burning cool temperatures. up" of the growth reserves. Shallow and/or sandy soils with low water-holding abil- Soil requirements: Maize ity. grows well on a wide variety of Excessive water runoff due to soils if drainage is goOd (no water- lack of erosion control on sloping land. logging). It has a deep root sys- Low humidity, especially tem (up to 185 cm) and benefits when combined with wind. from deep soils which allow for im-

, Maize has some ability to proved moisture storage in dry resist dry spells but is not nearly spells. The optimum pH far maize as drought-tolerant assotihum and is in the 5.5-7.5 range, although millet. some tropical soils produce.good Temperature: The optimum yields down to a pH of 5.0 (very growth rate of maize increases with acid). The liming and nutrient temperatures up to about32-35°C if needs of maize are covered_in soil moisture is abundant, but de- Chapter S. creases slightly with temperatures Response to Daylength: -The around 27-30.C-when soil moisture length of grovith period of mdny is adequate. If soil moisture is plants is affected by daylength. low, the optimum growth rate tem- This is known as a photosensitive perature drops to27°C or below.: (photOperiodic) response. Most At temperatures of10°C or below, maize varieties are short day plants maize grows slowly or not at all which means that they ,will mature and is susceptible to frost. How- earlier if moved to a region with ever, daytime temperatures in ex- significantly shorter daylengths cess of32°C will reduce yields if than they were bled for. In the they occur during pollination. tropics, there is relatively little

44 52 Variation in daylength during the maize, but the only nutritional dif year or between regions. Because ference between the two is the pre- most temperate zone maize varieties sence of Vitamin A in the yellow are adapted to the longer daylengths variety (also called carotene). of that area's summer, they will Unlike production in the de- . flower and mature in too short a veloped countries, maize production period for good yield accumulation in developing countries is almost if moved to the tropics. Sweet entirely used for human food in the maize seed from the temperate zone . form' of mea P flour, tortillas or a may reach little more than -knee thick paste.40.In humid areas where height in the tropics, and produce increased spoilage problems make disappointingly small ears, although grain storage more difficult, a sig- in record time! 'Likewise, the nificant portion of maize may be "giant" novelty maize advertised in consumed much-like sweet corn while some gardening magazines is nothing it is st 1 in the semi -soft, imma- more than a variety adapted to the ture sta e. very short daylengths of the tropics. Maize has numerous industrial s When grown in the temperate zone, and food uses in the form of some the much longer daylengths retard 500 produc/ts and by -products. Vari- maturity and favor vegetative . ous milling and processing methods growth. 1 Some maize varieties, how- can produce starch, syrup, animal ever, are dayneutrbl with little feed, sugar, vegetable oil, "dextrine, response to variations in day- breakfast cereals, flour, meal, and length. acetone. Maize also 'ts used for As mentioned earlier, maize's making alcoholic beverages through- relatively low 'protein and high out the world: -starch content makes it more impor- Maize Stages of Growth tant as an energy (calorie) source. Depending on the variety and Many people believe that yellow growing temperatures,-maize reaches maize has more protein than white physiologic maturity (the kernels

. ,

ti 53 4

have ceased accumulating protein and ther. Little' if any germination or starch) in about 90-130 days after growth occurs at soil temperatures. plant emergence when grown in the below 13°C. Harmful soil fungi and tropics at elevations,of 0-1,000. insects are still active in cool meters. At higher elevations, it soils and can'causeheavy damage be- may take up to 200-300 days. Even fore the seedlings can become estab- at the same elevation and tempera- lished. Fungicide seed treatments ture, some varieties will mature (see Chapter 6) are usually most much earlier than others and are beneficial under cool, wet condi- known as early varieties. The main tions and may increase yields from difference between an early, (90-day) 10 to 20 percent. and a -late (130-day) variety is in Maize seeds are large and con- the length of time from plant emer- tain enough food reserves to sustain gence to tasseling (the vegetative growth for the first week or so after period). This stage All vary from emergence. Then the plants must rely albout 40 to 70 days. The reproduc- on nutrients supplied by the soil or tive period (tasseling to maturity) fertilizer. Up until knee-high for both types is fairly similar and sta0,.the three major nutrients -- varies from about 50 to 58 days. nitrogen, phosphorus, and potassium The following discussion describes -- are required in relatively small the growth stages and related man- amounts, but young seedlings do need agement factors of a 240-day maize a high concentration of phosphorus variety. near their roots to stimulate root PHASE I: development. FROM GERMINATION TO TASSELING. The primary roots reach full Plants will emerge in four to development about two weeks after

five days under warm, moist condi- seedling emergence and are then re- tions but may take up to two weeks placed-by the permanent 'roots (called or more during cool or very dry wea- nodal roots) which begin growlng .

46 $4

40 from the crown (the underground base lengthening of the stalk and switcho.i of the plant between the stem and the from leaf production to tassel initi- roots). Planting depth determines ation within the plant. (Slit a the depth at which the primary roots plant lengthwise at this stage, and ; form but has no effect on the depth you can easily see the growing point at which the permanent roots begin as i peaked tip inside the stalk).. to develop. At this time roots from adjacent Until the plants are knee rows have reached and crossed each high, the growing point (a small other in the between-row spaces (for. cluster of cells from which, the rows up to one meter wide). leaves, tassel, and ear originate) From tassel .initiation until is still below the soil surface, en- tassel emergence takes about five to cased by a sheath of unfurled leaves. six weeks and is a period of very A light frost or bail may kill the rapid growth in plant height, leaf above-ground portion of the plant, size, and/ root development. Maxi- but usually the growing point (if mum root depth can reach 180 cm. / below ground) will escape injury, under optimum soil, moisture, and and the plant will recover almost fertility conditions and is attained ,completely. However, flooding at by the time of tassel emergence. this stage is more damaging than Maximum nutrient uptake oc- later on when the growing point has curs from about three weeks before beenca;ried a6Ove ground by the to three weeks after tasseling and stalk. maximum water use from tasseling The growing point plays a through the soft-dough stage (about vegetative role by producing new three weeks after tasseling).

leaves (about one every two days) PHASE II: until the plants are knee high; TASSELING ANMPOLLINATION then a major change occurs.Within Tasseling occurs about 40-70 a few days, theunderground growing days after plant emergencn 90-130 point is carried above ground by a day varieties. The tassel/ (flower)

47 is thrust out of the 'oaf whorl sop.) or Tapanese beetle (Popillia about one to two days before it be- japonica) can-cut off the silks gins shedding pollen. Pollen shed before pollination. starts two to three days before the Maize is cross-pollinated, silks emerge from the ear tip and and usually 95 percent or more of continues for five to eight days. the kernels of a cob receive their If conditions are favorable, all the pollen from neighboring maize silks emerge within three to five plants. This also means that- days and most are pollinated the different maize types such as the first day. hi-lysine varieties must be kept Each silk leads to an ovule isolated from other maize pollen if (a potential kernel). When a pollen they are to retain their desired grain linds on a silk, it puts out a characteristics. oll.a.atube that grows down the Pollination is a very criti- silk's center and fertilizes the cal time during which there is a high

, ovule at the other end in a matter demand for both water and nutrients. of hours. Shortage of pollen is One to two days of wilting during rarely a problem since about 20,000 - this period can cut yields by as 50,000 pollen grains are produced much as 22 percent and six to eight per silk. Poor ear fill (the numb :r days of wilting can cut yields by 50 of kernels on an ear) or skipped percent. kernels are nearly always caused by A few days after pollination, delayed silk emergence or by ovule the silks begin to wilt and turn abortion, both ,of which are caused brown. Unoollinated silks will re-

by drought, overcrowding or_s shor- main pale and fresh looking for tage of nitrogen and phosphorus. several weeks but as mentioned Extreme heat (above 35°C) can di- above, they can only receive pollen minish pollen vigor and also affect for a week or so after they emerge ear fill. Some insects like the from the ear tip. corn rootworm beetle (Diabrotica

48 56 PHASE III: Roasting_ear stage: About FROMiKERNEL DEVELOPMENT 18-21 days after pollination. Though field maize has a much TO MATURITY lower sugar content than Most maize ears have 14-20 sweet maize, at this stage it is still sweet. At this stage rows with 40 or more ovules per row the kernels have accumulated and produce about 500-600 actual only .about one-third of the total dry matter yield they kernels. Any shortage of water, will have at physiologic nutrients; or sunlight during the maturity. From this time on, any type of stress is more first few weeks of kernel develop- likely to affect kernel size ment usually affects the kernels at .rather than grain fill at the ear tip. the tip of the ear first, making them shrivel or abort. Maize is Dough stage: About _24-28 days after pollination. very prong to moisture stress (water deficiPncy) at this stage due to a Approaching maturity: As ma -.. turity nears, the lower heightened water requirement (up to leaves begin to turn yellow 10 mm per day under very hot and dry and die. In a healthy, well nourished plant, this should conditions). not occur until the ear is Wind damage during early ker- nearly mature. However, any serious stress factor- - nel development is seldom serious, drought, low soil fertility, even though the plants may be excessiveheat, diseases--can cause serious premature leaf knocked almost flat, since they ,death. Ideally, most of the still have the ability to "goose- leaves should still be green when the husks begin to neck" themselves (curve up) into a ripen and turn brown. Early nearly vertical position. deatti\of.thp maize plant can great1Y\reduce yields and re- Stages of Kernel Development sult in ainall, shrunken kernels. in Maize Blister stage: About 10 clan Physiologic maturity: About after pollination when the 52-58 days after 75'percent kernels begin to swell, but of the field's ear silks have contain liquid with very emerged. The kernels have little solid matter. reached their maximum yield

49 57 and have ceased accumulating able to produce at least one ear. more dry matter. However, they still contain about 30- 35 percent moisture which is too wet for damage-free com- Grain Sorghum bine harvesting (picking and (Sorghum bicolor) _ shelling) or for spoilage- free storage (except in the form of husked ears in a Distribution and Importance narrow crib; see Chapter 7). Although grain sorghum ac- Small farmers usually let counted for only 3.6 percent of the maize stand in the field unharvested for several total world cereal production in weeks or more to allow some 1977 (FAO data), several factors further drying. In some areas,-particularly Latin make it an especially Important America, it is a common prac- crop in the developing world: tice to bend the ears (or the plants and the ears) down- The developing nations account ward to prevent rain from for about 60 percent of the entering through the ear tips world's grain sorghum pro- and causing spoilage, It duction. also helps minimize bird It is drought-resistant and damage and lets in sunlight heat-tolerant and particu- for any intercropped plants larly suited to the marginal that may be seeded at this rainfall areas of the semi- time. arid tropics (such as the Number of ears per jlant: Most savanna and Sahel zones of tropical and sub-tropical maize va- Africa where food shortages have been critical) . rieties commonly produce two to three useful ears per plant under Types of Sorghums good conditions. In contrast, most Grain Sorghum vs. Forage U.S. corn belt types are single Sorghum: Where sorghum is grown in eared. One advantage of multiple- the developed world, a definite dis- _ eared varieties (often called pro- tinction is made between forage sor- lifics) is that they have some built ghum and grain sorghum types. For in buffering capacity in case of example, in the U.S. (where grain adverse conditions and may still be sorghum is often called "milo "),

50 58 nearly all grain types have had variety of forage sorghum with dwarf genes bred into them to reduce especially small seedheads and thin- plant height to 90-150 cm for more bladed leaves, and sorghum-sudan managable machine harvesting. In crosses also are available. Contrast, forage sorghum. types are In the developing countries, much taller and have smar : seeds especially where cattle are impor- and a higher rat4o of stalk and tant, most traditional grain sorghum* leaves to grain. They are used varieties have some forage type largely for cattle feedas fresh characteristics such as tallness and green chopped forage orsilage a high proportion of stalk to leaves. (green forage preservedby a fer- There are many regional vari- mentation process), butare some- ations among local grain sorghum times grazed. Sudangrass is a types:

Yields of Dry Grain

Lbs./Acre KR/Hectare Top yields in the U.S. under irrigation 9000-12,000 100300-13,4000

Top rainfed yields in the U.S. 5000-8000 5600-9000

U.S. Average 3130 3520

Average for the developed countries 2900 3260

Average for developing countries 400-800 450-900

Feasible rainfed yields for 3360-5000 3000-4500 farmers using Impro7ed practides

60 Sweet Sorghum (Sorgo) and likely to be highest under very low Broomcorn: Sorgo types have tall, rainfall that cuts back yields and juicy stalks with a high sugar con- concentrates the limited amount of tent and are used for making syrup N in a smaller amount of grain. and also for animal feed in the Protein fluctuation is much less on form of silage and forage. Broom- soils with adequate nitrogen. corn is a sorghum type grown for its Climatic Requirements of Sorghum brush, which is used mainly for Grain sorghum tolerates a brooms. wide range of climatic and soil Sorghum Yields conditions. Gran sorghum exhibits Rainfall: The sorghum plant, greater yield stability over a wider aside from being more heat- and range of cropping conditions than drought-resistant than maize, also maize. Although it will outyield withstands periodic waterlogging maize during below-normal rainfall without too much damage. periods, the crop might suffer some The most extensive areas of damage under very high rainfall. grain sorghum cultivation are found Yields of dry (14 percent moisture) where annual rainfall is about 450- grain are shown under varying grow- 1,000 mm, although these higher ra ining conditions on page 52 (based on fall areas favor the development of FAO, USDA, and international research fungal seed head molds that attack institute data). the exposed sorghum kernels. The Protein content vs. yield: The pro- more open-headed grain sorghum vari- tein content, of sorghum kernels .can eties are less susceptible to head vary considerably (7-13 percent on mold. soils low in nitrogen) due to rain- Several factors account for fall differences. Since nitrogen (N) the relatively good drought tolerance' is an important cpnstituent of proof grain sorghum: tein, kernel protein content is Under drought conditions the

53 61 plants become dormant and will varieties in the developing countries curl up their leaves to re- In these duce water losses due to are very photosensitive. transpiration (the loss of photosensitive types, flowering is water through the leaf pores into the air). stimulated by a certain critical minimal daylength and will not occur The leaves have a waxy coating that further helps to reduce until this has been reached, usually transpiration. at or near the end of the rainy The plants have a low water This delayed flowering en- requirement per unit of dry season. weight produced and have a ables the kernels to develop and very extensive root system. mature during drier weather while relying on stored soil moisture. Temperature and Soil Requirements: (This is actually a survival feature Although sorghum withstandstuh which allows seed heads to escape temperatures well, there are varie- fungal growth in humid, rainy con- ties grown at high elevations that ditions.) These local photosensi- have a good tolerance to cool weather tive varieties usually will not as well. tight frosts may kill the above-ground portion of any sorghum yield as well outside their home areas (especially further north or variety, but the plants have the south) since their heading dates ability to sprout (ratoon) from the crown. still remain correlated to the rainy season and daylength patterns Sorghum tends to tolerate very of their original environment. De- acid soils (down to pH 5.0 or slightly below) better than maize, yet it spite this apparent adaptation to is also more resistant to salinity their own areas, the traditional photosensitive varieties have a re- (usually confined to soils with pH's latively low yield potential and may over 8.0). occupy land for a longer period to Response to Daylength (Photosensi- produce a good yield (due to their tivity), fixed flowering dates). In addition Most traditional sorghum

62 there is always the danger that the *DANGER* The Toxicity Factor: rains will end early and leave an Hydrocyanic Acid inadequate reserve of soil moisture Young sorghum plants or for kernel development.Breeding drought-stunted ones under 60 cm programs are attempting to improve tall contain toxic amounts of these photosensitive types, and many hydrocyanic acid (HCN or prussic of the improved varieties show lit- acid). If cattle, sheep or goats tle sensitivity to daylength. are fed on such plants, fatal Other Sorghum Characteristics poisoning may result. Fresh, Ratooning and Tillering Ability green forage, silage, and fodder The sorghum plant is a peren- (dried stalks and.leaves) are nial (capable of living more than usually safe if over 90-120 cm two years).. Most forage sorghums tall and if growth has not been and many grain varieties can produce interrupted. .The HCN content of several cuttings of forage or grain sorghum plants decreases as they from one planting if not killed by grow older and is never a problem heavy frost or extended dry weather. with the mature seed. An intra- New stalks sprout from the crown venous injection of 2-3 grams of (this is called ratooning) after a sodium nitrite in water, followed harvest. by 4-6 grams of.sodium thiosulfate However, ratooning ability, is the antidote for HCN poisoning has little value in most areas where in cattle; these dosages are re- non-irrigated sorghum is grown. In duced by half for sheep. these areas, cither the rainy season or frost-free period is likely to be too short for more than one grain ing, since they are harvested well crop or too wet for a mid-rainy sea- before maturity, usually at the son first crop harvest without head early heading stage. Cattle farmers mold problems.However, forage sor- in El Salvador take three cuttings ghums take good advantage of ratoon- of forage sorghum for silage-making

55 63 during the six-month wet season. fuel and fencing or building meter-

. In irrigated tropical zones with a tal year-round growing season such as Like the other cereals, grain Hawaii, it is possible to harvest sorghum is relatively low in, protein three grain crops a year from one (8 -13 percent) and is more important sorghum planting by using varieties as an energy source. If eaten with good ratooning ability. along with pulses in the proper Some grain sorghum varieties amount (usually a 1:2 grain:pulse have the ability to produce side ratio), it will provide adequate shoots that grow grain heads at about protein quantity and quality. Only the same time as the main stalk (this those varieties with a yellow endo- is called tillering). This enables sperm (the starchy main portion of such varieties to at least partially the kernel surrounding the germ) make up for too thin a stand of contain vitamin A. plants by producing extra grain Because sorghum is very susceptible to bird damage during kernel heads. ti Nutritional Value and Uses development and maturity, bird- of(Sorghum resistant varieties have been devel- - Nearly all grain sorghum used oped. Because it has a high tannin in the developed world is fed to content in the seeds, stalks, and livestock (mainly poultry and swine). leaves, it is partly effective in However, in developing countries it repelling birds' from the maturing is an important staple food grain seedheads. However, these high tan- and is served boilcd or steamed in nin varieties are more deficient in the form of gruel, porridge, or the esrential amino acid lysine than bread. In many areas, it is also ordinary varieties which has conse- used to make a home-brewed beer. In quences for humans and other mono- addition, the stalks sr': leaves are gastrics like pigs and chickens. In often fed to livestock and used as the U.S., this is overcome by adding

56 64 sythetic lysine to poultry and swine matter what variety is grown. rations that are made from bird-re- PHASE I: sistant sorghum grains. In develop- FROM EMERGENCE TO THREE WEEKS ing countries a slight increase in Sorghum seedlings will emerge pulse intake can overcome this %pro- in three to six days in warm, moist blem in humans. soil. Under cool conditions where Grain Sorghum Growth Stages emergence is delayed, the seeds are Depending on variety and especially prone to harmful soil growing temperatures, non-photosen- fungi and insects, and a fungicide/ sitive grain sorghum reaches physio- insecticide seed dressing may be logic'maturity in 90-130 days within particularly beneficial (see Chapter the '0-1000 m zone in the tropics. 6). Compared to maize, the small However, the local, daylength- sorghum seeds are low in food re- sensitive varieties may take up to serves which are quickly exhausted 200 days or more because of delayed before enough leaf area is developed flowering. At very high elevations. for photosynthesis. For this reason all varieties may take 200 days or the seedlings get off to a slow more. start during the first three weeks, As with maize, the main dif- after which the growth rate speeds ference between a 90-day and 130 - up. day sorghum variety is in length of This sluggish beginning makes vegetative period (the period from good weed control extra important seedling emergence to flowering). during this time. The grain filling period (pollina- For the first 30 days or so, tion-to maturity) is about the the growing point which produces the same for both (30-50 days). The leaves and seedhead is below the following sections describe the soil surface. Hail or light frost growth stages and management fac- is unlikely to kill the plant, since tors of a typical 95-day variety. new growth can be regenerated by the

These principles remain the same no growing point. However, ,'regrowth at

57 a 65 this stage is not as rapid as with half-bloom on a per plant basis maize. occurs when flowering has proceeded PHASE II: halfway down the head. Although

FROM THREE WEEKS TO HALF-BLOOM time to half-bloom varies with vari- ` (60 days after emergence) ety and climate, it usually encom- Growth rate and the intake of passes two-thirds of the period from nutrients and water accelerates seedling emergence to physiologic rapidly after the first three weeks. maturity. In keeping with the rapid The "f lag" leaf (the final leaf pro- rates of growth and nutrient intake, duced) becomes visible in the leaf about 70, 60, and 80 percent of the wborl about 40 days after emergence. nitrogen, phosphorus, and potassium "Boot" stage is reached at about 50 ,requirements (respectively) have days when the flower head begins to been absorbed by the plant by the emerge from the leaf whorl but is time of half - bloom. Severe moisture still encased oy the flag leaf's shortage at pollination greatly cuts sheath. The head's potential size yields by causing seed ovule abor- in terms of seed number has by now tion and incomplete pollination. been determined. Severe moisture PHASE III: shortage at boot stage can pteventi FROM HALF-BLOOM TO PHYSIOLOGIC the head from emerging completely MATURITY (60-95 dates)' from the flag Itat7sheath. This The seeds teach the soft

will prevent complete pollination ; dough stage about 10 days after pol- at flowering time. linStion(70 days after emergence) Half-bloom stage is.reached in a 95-day variety, and about half at about 60 days when about half of of the final dry weight yield is ac- the plants in a field are in" some cumulated during this short period. phase of flowering at their heads. Hard dough stage is reached in However, an individual sorghum plant another 15 days (85 days after emer- flOwers from the tip of the head gence) when about three-fourths of downward over four to nine days, so' the final dry weight grain yield has

58 66 been attained. Severe moisture or let the heads diy naturally on stress during this period will pro- the plants in the field. duce light, undersized grain. Phy- siologic maturity is reached in The Millets another 10 days (95 days from emergence in the case of this variety.)

At this stage, the grain still con- TYPES OF MILLET tains 25-30 percent moisture which The millets comprise a group is well above the 13-14 percent safe of small-seeded annual grasses grown limit for storage in threshed form for grain and forage. Although of (after the seeds have been removed little importance in the developed from the head). Small scale farmers world, they are the main staple food can cut the heads at this stage and grain crop in some' regions of Africa dry them inthe sun before threshing and Asia and are associated with

Foxtail Proso Japanese Pearl Millet Millet Millet Millet

59" semi-arid conditions, high tempera- southern Sudan, northern tures, and sandy soils. Of the six Uganda, southern India, the major millet types listed below, foothills of Malaysia aid Sri pearl millet is the most widely Lanka' grown and will receive the most em- Important Characteristics:Unlike phasis in this manual. other millets, it needs cool Pearl Millet weather and higher rainfall; Other Names: Bulrush, cattail, and higher in protein than the

-1.. spiked millet, bajra, millet, others. mil. Scientific Name: Pennisetum typhoi- Pro so Millet des, P. glaucuu or P. ameri- Other Names: Common, French, and canum hog milletpanicum, milia- Main Areas of Production: Semi-arid ceum plains of southern Asia (es- Scientific Name: Panicum miliaceum pecially *India) and the Sahel Main Area of Production: Central Asia, USSR (sub-Saharan) regionoflAfri- % ca. Important Characteristics: Used Important Characteristics:The most mainly as'a short-duration drought- and heat-tolerant of emergency crop or ftriiated the millets; more prone to crop. bird damage than finger mil-

let. Teff Millet Scientific Name: Eragrostis abys-

Finger Millet sinica Other Names: Birdsfoot millet, /,Main Area of Production: Mainly the eleusine, ragi Ethiopian and East African Scientific Name: Eleusine coracana laighlandswup to 2700 m- where Main/frees Productioni, The A it is an important staple food.

60 68 Japanese or Barnyard Millet yielded 1000-1500 kg/ha and improved Other Names: Sanwa or shams millet' varieties have produced up to 2000- Scientific Name: Echinochloa crus- 3500 kg/ha. E. frumentacea Climatic Requirements of Millet Main Areas of Production: India, Rainfall: Pearl millet is East Wsia, parts of Africa; the most important cereal grain of also in the Eastern U.S. as the northern savanna and Sahel a forage region of Africa. It is more Important Characteristics:Wide drought resistant than sorghum and adaptatjip in terms of soils can be grown as far north as the and moisture; cakes longer to 200-250 mm rainfall belt in the Sa- mature (three to four months hel where varieties of 55-65 days total) than the others. maturity are grown to take advantage of the short rainy season. Although Foxtail Millet pearl millet uses water more effi- Scientific Name: Setaria italica ciently and yields more than other Main Area of Production: Near East, cereals (including sorghum) under mainland China high temperatures, marginal rainfall, Important Characteristics:Vety sub-optimum soil fertility, and a drought-resistant. short rainy season, it does lack sorghum's tolerance to flooding. Millet Yields Soil: Pearl millet with- Average millet yields in West stands soil salinity and aftaline Africa range from about 300-700 kg/ conditions fairly well. (For more ha. They tend to be low due to mar- information on_ salinity and alka- ginal growing conditions and the linity problems, refer to Peace relative lack of information concer- Corps, Soils, Crops, and Fertilizer ning. improved practics. Compared to Manual, 1980 edition.) It is also- maize,, sorghum, and peanuts, re- less susceptible than sorghum to search efforts with millet have only boring insects and weeds, but shares

61 69 -

sorghum's susceptibility to losses, laborious thinning of the seedlings from bird feeding, which damages the about two to three weeks later. The maturing crop. tiny millet seeds are low in food Nutritional. Value and Uses ofMillet reserves which becoMe exhaystedbe- Pearl, (oxtail, and pro o fore the seedlings can produce enough leaf area for efficient photo- millets all contain about 12 63 14 synthesis and enough roots for good percent protein which is somewhat nutrient intake. Therefore, as with higher than most other cereals. The sorghum, the growth rate is very most common method of prepOring pearl slow for the first few weeks. millet.in West Africais4/s"kus-:kds" Two general classes of pearl or "to", a thick paste/Made by mixing millet are traditionally grown in millet flour with boiling water.i ------West Africa: Millet is used alsolto makebeer!. The stalks and leaves are an impor- The Gero class whose.varieties are le5-3.0 m tall, early ma- tant livestock forage and also serve turing (75-100 days5,*and as fuel, fencing, and building ma- neutral or only slightly photosensitive in daylength terial. response. In Some parts of ' Traditional Pearl Millet Crowing the savanna, these short- season Geros mature at the Practices in West Africa peak of the wet season, but The traditional west African, have good resistance to the fungal seedhead molds and pearl millet varieties are generally insects favored by the rains. and a The Geros make up about 80 m tall with thick stems percent_of the Legion's poor harvest index. They are usually, millet and are preferred for planted in clumps about a meter or their higher yields and shorter maturity over the so apart, very dften in combination Maiwa class. They mature in with one to three of the other July- August in the Guinea savanna and August-September .reference crops, usually sorghum, in the Sudan savanna. cowpeas, and groundnuts. Many seeds The Maiwa class is taller (3- _are sown per clump, followed by a 5 m), later maturing (120-

62 ..,, 7 280 days), and much more non-synchronous, that is tillering photosensitive in daylength development lags behind that of the response than the Gero group. As with the photosensitive main stem. As a result, these secon- sorghum varieties, tne Maiwas dary shoots mature later than the will not flower until at or near the end of the rains, main stem. If soil moisture re- which allows them to escape serious head mold and insect mains adequate, two or more smaller damage. However, they yield harvests can be taken. less than the Geros and account for only about 20 per- Aside from the normal rainfed cent of the region's millet. millet produttion, the crop is also In the higher rainfall por- planted on flood plains or along tions of the savanna 500-600 river borders as the waters begin to mm per year where both millet and sorghum can be grown, recede. This system is referred to farmers usually prefer to plant photosensitive sorghum as recessional agriculture and a ).so varieties. These have about may involve sorghum. the same length of growing period, but yield more than the Maiwas due to a longer Peanuts grain-filling period. How- (Arachis hypogea) ever, the Maiwas are favored over the sorghums on sandier soils with lower water storage ability. Some farmers will DISTRIBUTION AND IMPORTANCE also choose the Maiwas over ----the sorghums because the for- Peanuts are an important cash mer mature slightly sooner, and staple food crop in much of the thus spreading out the har7 vest labor demands for. these developing world, particularly in late season crops. (The West Africa and the drier regions of Maiwas are harvested a month or sointo the dry season.) India and Latin America. The devel- Many_of the traditional mil- oping nations account for some 80 lets produce abundant tillers (side percent of total world production,_ shoots produced from the plant's with two - thirds of this concentrated crown). However, this tillering is in the semi-arid tropics. Because

63 71 of repeated droughts, disease prob- emerge sequentially (in op- lems, and other factors, Africa's posed pairs), and their leaves are lighter green. share of the world peanut export They have a shorter growing period (90-110 days in warm market declined from 88 percent in weather), are highly suscep- 1968 to 43 percent in 1977, while tible to Cercospora leaf spot, its share of total production fell and have little or no seed dormancy. Pre-harvest sprou- from 36 percent to 26 percent during ting can sometimes be a problem under very wet conditions the same period. or delayed harvest. They are Tykes of Peanut s generally higher yielding than the Virginia variety if There are two broad groups of leaf spot is controlled. peanuts: Plant breeders have made some Virginia group: Plants are either of the spreading type promising crosses between these two with runners or of the bunch groups. (bush) type. Their branches emerge alternately along the Peanut Yields stem rather than in opposed Average peanut yields in the pairs. The Virginia varieties take longer to mature developing countries range from (120-140 days in the tropics) about 500-900 kg/ha of unselled nuts, than the Spaaish-Valencia types and are moderately compared with the U.S. average of resistant to Cercospora leafspot, a fungal disease that 2700 ke/ha, based on 1977 FAO data. can cause high losses in wet Farmers participating in yield con- weather unless controlled with fungicides (see Chapter tests have produced over 6000 kg/ha 7). The seeds remain dor- under irrigation, and yields of mant (do not sprout) for as long as 200 days after devel- 4000-5000 kg/ha are common on exper- opment, which helps prevent iment station plots throughout the pre-mature sprouting if they are kept too long in the world. Feasible yields for small ground before harvest. farmers who use a suitable combina-

Spanish-Valencia sroup: tion of improved practices are in Plants are of the erect bunch the range of 1700-3000 kg/ha, depend- type and non-spreading (no runners). Their branches ing on rainfall. 72 64 Each peg has an ovary at its tip and penetrates the soil aboUt 3-7 cm before developing into a peanut. Climatic and Soil Adaption of are unsuitable, since penetration Peanuts of the pegs is unhindered. Rainfall: Peanuts have good drought Clayey soils can produce good resistance and heat tolerance. results if well drained, but harvest They mature in 90-120 days in warm (digging) losses may be high due to weather, which makes them espe- nut detachment if the plants are cially well suited to the short, "lifted" when such soils are dry and wet season of the northern savanna hard. On the other hand, harVest- zone of West Africa. They can be ing the crop on wet, clayey soils grown in moister climates if dis- may stain the pods and make them eases (especially leafspot) can be unsuitable for the roasting trade. controlled and if planted so that Peanuts grow well in acid harvest does not coincide with wet soils down to about pH 4.8, but do weather. have an unusually high calcium Temperature: During the vegetative requirement which is usually met by (leaf development) phase tempera- applying, gypsum (calcium sulfate). ture has little effect on yields. Peanut fertilizer requirements are However, the rate of flowering and covered in Chapter 5. pollen viability are greatly influ- Nutritional Value and Uses enced by temperatures during flower- of Peanuts ing (about 35-50 days after emer- The mature, shelled nuts contain gence). Pod production is adversely about 28-32 percent protein and vary affected by temperatures below 24°C from 38.47 percent oil in Virginia or above 33°C. At 38°C, for example, types to 47-50 percent oil'in Span-. flowering is profuse, but few pods ish types. They are also a good are produced. source of B Vitamins and Vitamin E. Soils: Peanuts do not tolerate water- Although lower in the essential amino logging, so good soil drainage is acid lysine (a determinant of protein important. Soils that crust or cake quality) than the other. pulses, pea-

66 74 0 nuts are a valuable source of protein. mature underground. In the developing nations pea- Peanut Stages of Growth nuts are consumed raw, roasted or boil- Depending on variety, peanuts ed or used in stews and 'sauces. The take anywhere from 90-110 days to oil is used for cooking and the hulls 120-140 days to mature. The pea- for fuel, mulching, and improving clay- nut plant will flower about 30-45 ey garden soils. days after emergence'and will con- Commercially, the whole nuts are tinue flowering for another 30-40 used for roasting or for peanut butter. days. The peanuts will then mature Alternatively, the oil is extracted us- about 60 days after flowering. ing an expeller (pressing) or solvent PHASE I - EMERGENCE method_and the remaining peanut meal Within a day or so after plant- or cake (about 45 percent protein) is ing in warm, moist soils, the rad- used in poultry and swine rations. icle (initial root) emerges and

Peanut oil is the world's second most may reach 10-15 cm in length within . popular vegetable oil (bEter soybean four to five days. About.four to oil) and can also be used to make mar- sex n days after planting, two cotyledons garine, soap, and lubricants. The break -.he soil surface where they hulls have value as hardboard and will re,in while the stem, branches,

building-block components. and leaves '-:egin to form above them. Plant Characteristics The plants gru- slowly in the early of Peanuts stages and are easil, overtaken by

Peanuts are legumes and can meeds. satisfy all or nearly all of their PHASE II- FLOWERING nitrogen needs through their sym- TO POLLINATION biotic relationship with a species' Flowering begins at a very slow of Rhizobia bacteria. A character- ,rate about 30-45 days after plant, . istic of the peanut plant is that emergence and is completed within the peanuts themselves develop and another 30-40 days. The flowers are

67 75 self-pollinated, but bees and rain of the kernels are not londer wrin- improve fertilization (and there- kled and the veins on the inside of fore kernel production) by "triggering" the shell have turned dark brown. the flowers and aiding in pollen Harvesting cannot be delayed until release. The flowers wither just five all the fruits have matured or to six hours after opening.A plant heavy losses will result from po may produce up to 1000 flowers, but detachment from the pegs and fro only about one out of five to seven premature sprouting (Spanish-Valencia actually produces a mature fruit. types only). Choice of harvesting PHASE III -.PEG EMER- date is an important factor in ob- GENC7 ro MATURITY taining good yields.

---.- The pegs. (stalk-like structures, Traditional Peanut Growing Practices each containing a future fruit at its tip) begin elongating from the witle- Small farmers in some develop- ered flowers about three weeks after ing countries, especially in West pollination and start to penetrate the Africa, often plant peanuts togeth- soil. After the pegs penetrate to er with one or more other crops such a depth of about 2-7 cm, the fruits as4sorghum, millet, cowpeas, cotton, begin to develop rapidly within a- and vegetables. Whether inter- bout 10 days and reach maturity a- cropped or sown alone, peanuts are

bout 60 days after flowering. usually planted on ridges (raised Those pegs that form 15 cm ro more up mounds or beds) about one meter above the ground seldom reach the apart; this improves soil drainage and soil and abort. facilitates digging. In the northern savanna areas of West Africa, they

It is important to note that are generally planted in June and the fruits do not all mature at, the harvested in September or October. same time, sinceflowering occurs In the southern, higher rainfall A over a long period. Ari individual sections of the savanna,- it is often fruitis mature-when the seed coats possible to grow two crops (April Or

68' 76 May until August for the first, and the 1975-77 period, world dry bean August or September to November or production was about 12.4 million December for the second). Most of tons annually. Latin America accounts the local varieties, especially in i for about a third of world production tbe more humid areas, are of the Vir- and produces mainly common (kidney) ginia type which has much better leaf- beans which are also the major type spot resistance. grown in East Africa. Cowpeas are the major grain legume (peanuts ex- Common Beans cluded) of the West Africa savanna And Cowpeas zone.

Importance and This section deals with common Distribution beans and cowpeas (dry beans). In

Along with peanuts, this group the appendices are similar descrip- makes up the bulk of the edible tions of other pulses such as pid- .,pulses grown in tropical and sub- geonpeas, chickpeas, lima beans, mung tropical developing nations. Aside beans, soybeans, and winged beans.. from their importance as a protein Common (Kidney) Beans source, the crops play an important (Phaseo!us via:gads) role in the farming systems of these areas: Other Names.. Field beans, frijoles, They are especially well suited to climates with alternating wet haricot beans, string beans (imma- and dry seasons. ture stage), snap beans (immature

Being legumes, they are partly to stage). wholly self-sufficient in meeting their nitrogen requirements. Types, Bean varieties can be classif- They are the natural partners of the cereals in intercropping and ied according to three basic character- crop rotations (see Chapter 4). istics - seed color, growth habit, According to FAO estimates for and length of growing period:

69 O 77 The flowers develop into pods af,ter pollination.

Part of a bean plant A bean pod. with flowerg.

1., Seed Color: Most are black or Given their longer flowering per- red seeded, and there are us- iod, most indeterminates have un- ually distinct local prefer- even pod maturity with the harvest ences regarding color. period stretched out over a number of weeks. 2. Growth Habit: Varieties can be 3. Growth Period: In warm weather, erect bush, semi-vining or vin- early varieties can produce mature ing types; the latter have a pods in about 70 days from plant vigorous climbing ability and emergence, while medium and late require staking or a companion varieties take 90 days or more. support crop like maize. Bush Time to first flowering ranges varieties flower over a short between 30 and 55 days. With -Ise period with no further stem and exceptions, the erect busy types leaf production afterwards; these reach maturity earlier than the t are called determinate. The vin- vining indeterminate types. Plant ing types flower over a longer per- breeders are developing ind. eter- iod and continue leaf and stem pro- miniate varieties with shorter, duction; these are called indeter- growing periods and more compaox minate. Semi-vining varieties can maturity.

be of either type. -

70 78 MimeticRequiremeritsof Beans high levels of soluble manganeie Rainfall: Comion beans are not well and aluminum which often occur at suited to veryhighrainfall areas the lower .pH levels. (such as the humid iainforest zones Daylength: Unlike some sorghums and of tropical Africa) because of in- millets, most beans types show lit- creased disease and insect pro- tle response to daylength variations: blems. Ideally, planting should Iutritional Value and Uses of Beans be timed so_that-the' latter-stages Common beans contain about 22 of growth and harvest occur during percent protein on a dry seed basis. reasonably dry weather. They provide adequate protein Temperature: Compared to sorghum quality and quantity for older chil- and millet. beans do.not,tolerate dren and adults if eaten in the pro- extreme heat or moisture stress per proportion with.cereals (about a well. Few varietiesare adapted 2:1 grain:pulse ratio. In the to daily mean temperatures (aver- green bean form, they provide lit- age of daily high and low) over tle protein, but are a good source 28°Cor below14°C. Optimum tem- of Vitamin A. The leaves can be. peratures for flowering and pod eaten like spinach and also are us- set is a daytime high of29.5°C and ed as livestock forage.

0 a nighttime low of21°C. Blossom Cowpeaf- Vigna sinensis, drop'becomes serious over 36°C and V. ungviculata, is aggravated also by heavy down- V. sex' uipedalia) pours. Soil: The plaits are very suscept- Other Names: Black-eyed peas, south- ible to fungal root rot diseases, ern peas, crowder peas. and good drainage is very import- Types

ant. They usually grow poorly in Cowpeas have much the same variations in'seed color, grOwth habit, acid soilsmucd below pH 5.6, since and length of growing period as they are especially sensitiveto the

71 U

r. common beans (see page 69), except ation. Field trial yields in Africa that cowpea seeds are usually brown and Latin America are largely in the -mu white. There are three separate 1300-2000 kg/ha range with some over species: 3000 kg/ha. Vigna Sinensis: the common cow-, CLIMATIC REQUIREMENTS OF COWPEAS pea in Africa and most'of Latin Rainfall: Cowpeas are the major grain America. The large, white seeded types are preferred in most legume (peanuts excluded) of the West of West Africa. African savanna Vigna unguiculata: catjung cow- (zone). However, they also are growl' pea, a primitive type found in many other regions. They have mainly in Asia, but also in Africa. better heat and drought tolerance than common beans, but the dry seed Vigna sesquipedalia: the aspar- agus or yardlong bean widely does not store as well and is very grown in Asia mainly for its susceptible to attacks by weevils immature pods. (see Chapter 7). Most traditional varieties tend Temperature: to 4e late maturing (up to five months) High daytime temperatures have and vining. Improved,bush (little little effect on vegetative growth or no vining) types are available but will reduce yields if they occur andclepableof producing good yield after flowering. High temperatures -in 80 -90 days. at this time can cause the leaves to Growing Practicrm and Yields of cowpeas senesce (die off) more quickly, short- Traditional practices andyield ening the lengthof the pod-filling constraints pf cowpeas are similar. period. High temperatures will also -to those of common beans. Average increase the amount of blossom drop. yields in the developingcountries As with common beans and most cropp, run from 400-700 kg/ha of dry seed. humid, rainy weather increases dis- compared to a California (U.S.) aver- ease and insect problems. Dry weather age of about 2200kg/ha under irrig- is needed during the final stages of.

. SO 1 growth and harvest to minimize pod o Improving existin g cropland / rots and other diseases. o Extending cultivation tonew,/un- Soil: Cowpeas crow well' on a wide cropped areas variety of soils (if they are well o Improving the infrastructurb drained) and are more tolerant of soil acidity than common beans. o Establishing crop improvement programs. Nutritional Value and Uses of Cowpeas The dry'seeds contain about 22- Any meaningful production increase will require varying emphasis on all 24 percent protein. The immature four methods. seeds and green pods also are eaten. They are considerably lower in protein than the mature seeds, but are.an Improving Existing excellent source of Vitamin A wh Cropland green, as are the young shoots a d- Unquestionably. improved drain- leaves. The plants are a good ive- at (by land leveling', runoff canall4 stock forage and are sometimesrown or underground tile drains) and eros- as a green manure and cover cr p (see ion control are high-4.ain investments. Chapter 5). Erosion control not only reduces soil losies and yield deterioration, but in many cases actually improves pro- Increasing duction by increasing the amount of Reference Crop rainfall retained by the: soil. In the case of irrigation pro- Production jects, however, the results are often mixed. Many irrigation projects have paid little attention to the potential

There are basically four environmental damage or to the tech-. ways of increasingthe produc- nical problems and soil types involv- tion of the reference crops: ed. Huge dams and artificial lakes

73 81 IA

have definite appeal on paper, but while cultivated land area grew by have often led to drainage and salt only two-percent: Estimates concern- accumulation problems, as well as to ing the amount of additional cul-- weed-choked canals and serious health tivable land differ consideribly, hazards likemalaria and schistoso- but suggest that the world ps a miasis,(bilharzia). whole is utilizing only about one- Pumping projects relyingon wells third to -one -half of actual and face similar problems and can ser- potential arable land (suitable for iously lower the water table to the crops or for fivesock). he larg- point of endangering the supply. est areas of "new" land are. in the Water alone'is nbt enough tiassure lowlaid tropics of Latin America, profitable yields which must be Africa, and Southeast Asia. high to cover the added costs of There are, however some drawbacks:

'irrigation. ,Unless such projects o Only a small percentage of these lands are capable of sustaining are carefully planned and combined intensive agriculture because with.a crop improvement program, of soil or climate factors; an alarming proportion has been the results are likely to be dis- claimed by land speculatOrs or appointing. is'being divided up into.ranch- es by investors, as in Brazil.

o Whether in high rainfall or, in arid regions, much of this land is prone' to accelerated erosion Extending Cultivation or irrigation-induced saliniza- To New Areas tiOn (accumulation of. salts at the soil surface).

o As we .have seen, most of. reference 'crops are nbt-. well adapt-

ed to high rainfall and humidity. . Pasture and perennial crops, may be the best choices under'these The FAO estimates that total constraints., world food production increased by about.% percent from 1963 -76,

74 82 Improving the The small farmers in most areas Infrastructure of the developing world do not enjoy the same access that larger farmers do to these essential factors of pro- In agriculture, the infrastruc- duction. Agricultural public works ture refers to those installations, projects such as irrigation, flood facilities, inputs, and servi s control, and farm-to-market roads are that encourage production. The usually undertaken acc9rding to pure most important of these are: economic feasibility or in response Roads and transport to special interest groups. Larger farmers in a number of developing Markets -and marketing standards countries, especially in Latin Amer- Storage facilities ica, are often organized into pro- Imiirovements to land such as ducer's associations with very drainage, erosion control, and irrigation effective lobbying powers. Inequities. in land tenure and Yield-increasing tecnnology distribution can have tremendous A viable extension service social and economic consequences and

Availability of agricultural can'effectively 'dampen farming in- machinery and equipment centives for those affected. In El

Political stability Salvador, 19 percent of the farms occupy about 48 percent of the land Credit and belong to wealthy "latifundistae An equitable land tenure and dis- (ranch -type farmers) who grow cotton, tribution system coffee; and sugarcane, frequently on National planning for agricul- an absentee basis. These farms are tural development concentrated on the country's best Crop prices-that encourage in- soil, while the "campesinos" (small creased output

75 83 ..,

farmers) are restricted to the eroded Crop Improvement and rocky hillsides where they grow Programs maize;, sorghum, and beans.About 47 percent of the country's farms are_ More than any other single fac- smaller than 2.47 acres (one hectare) tor, the development of yield-impro- and occupy only four percent of the totalving technology associated with the land. The majority of the farm units crop improvement programs of the in El Salvador, Guatemala, and Peru national and international research have been designated as sub-family. institutes'siTill play the major role While the implementation of most in increasing the yields of the,re- other infras.tructural' essentials is ference crops in the developing coun- hindered mainly by insufficient cap- tries. ital, land reform faces heavy political obstacles and'in some cases is not feasible in terms. of land supplies. Furthermore, when small farmers purchase land in densely popula- Reference Crop ted regions like the Guatemala High- lands, the Cibao area of the Domini- Improvement can Republic, and the lake regionof Programs Bolivia, competition frequently drives land prices too high for farming to be economical.

The term "crop improvement" is a broad one and refers to any attempt to improve crop yielas, quality, palatability or other

. characteristics through plant breeding or the development of improved

76 84 AWL growing, harvest, and storage birds by chemical or non- chemical methods practices. The most successful Adjustment of soil pH efforts are well-organized, multi- Control of soil compaction disciplinary (involving several due to equipment or animals relevant skill areas such as 41 Cropping sp-tem (monoculture entomology and soil fertility), versus intercropping; crop rotation) and crop-specific and aim at Harvesting, drying, and developing a "package" of improved storage methods practices centered around high- Non-manipulative factors! yielding, adapted varieties. In contrast to the production fac- A large number of yield- tors listed above there are a number determining factors and crop char - of others largely beyond the control acteristics can be at least par- of both the farmer and the crop tially manipulated or controlled improvement worker. These include by plant breeding and improved such variables as the weather and production practices, as shown in certain soil characteristics (i.e. the table on the next page. texture, depth,'tilth). Farming Practices Affecting Crop Yields and/or Quality .., Method of land preparation (type of tillage and seed- Crop Improvement bed) Programs for Fertilizer use (kind, amount, timing, placement) Individual Crops Variety selection Plant density and spacing Water management (soil Maize drainage, erosion control, moisture conservation practices) Potential for Improvement Control of weeds, insects, Of all the reference crops, diseases, nematodes, and maize has the highest yield paten-

77 85 BY-PLANT BREEDINGANDIMPROVED SUCCESS OFCONTROL ATTAINED CROP PRODUCTION

Control Attained Poor Poor to Fair Poor to Good Fair to Good Fair Good to Resistanceto Resispince General plant Crops inHarvest insects diseases A. vigor and General index Resistance to (ratio yield ability Resistance to nematodes droughts of stalk *Length of and leavesgrowing Resistance toNutritional to grain) period heat and-coldvalue Plant ar- 'Fertilizer Tolerance to Palatability chitecture response low or high & cooking (height, quality PH leaf size, Plant leaf density 'Tolerance to weight, tolerance 'low phospho- etc.) rou s

B. The Ref- erence Crops Husk cover- Maize ing Resistance to tipping over Ears/plant Resistance Sorghum/ Resistance to Photosensi- Ratoon-' to birds Millet striga weed tivity ing (millet) ability Resistance to Tillering head mold Vitamin A Bird (sorghum) (sorghum) resistance (sorghum) Resistance to Resistance Peanuts nematodes to leaf spot Susceptibility Seed dormancy to aflatoxin

Resistance to Seedcoat color disease and Beans and Growth insects Cowpeas habit (v in in& or bush) 78 86 tial in terms of grain production grams throughout the developihg per unit of land area under condi- world. In 1979, t/MMYT sponsored

tions of adequate moisture and international maize variety trials lb improved practices. Maize is gen- in 84 countries at 626 sites to I erally less troubled by insects and compare its varieties with those*

diseases than the pulses, especially from local and other foreign sources. beans and cowpeas. In addition, The Cfl1MYT- developed varieties more breeding work has been done originate from a well-organized breed- with maize than any other major ing program. During the 1970s the cen- food crop. ter developed 34 germ plasm pools (gen- Current Research Activities and etic groups) classified according to Crop Programs three climate types (tropical lowland, The Internatiollal Maize and tropical highland, and temperate), Wheat Improvement Center (C/MMYT)* four grain types (flint, dent, white, in Mexico is the institute most in- yellow), and three lengths

volved 4n maize improvement and acts of maturity' (early, medium, late). as the caretaker and shipping agent Advanced lines are developed from for the world's most complete col- these pools by selecting for yield, lection of maize gerinplasm (plant uniformity, height,' maturity, and genetic material). It cooperates resistance to diseases, insects, and extensively with the International lodging (tipping over). They are Institute for Tropical Agriculture -then grown at a number of locations (IITA) in'Nigeria and The Interna- in Mexico. The most promising are tional Center for Tropical Agricul- useein preliminary international ture in Columbia (CIAT) in their trials, and the best of thege become respective maize programs as well experimental varieties for more as with national improvemert pro- extensive trial work overseas.

* See "References", page.375, for international institute addresses.

79 87 Spreading Improvement Practices Peru, and Vc.....zuela all grain for Maize importing countries). From 1961-77, total maize pro- Disease and insect resis- duction in.tile:developing couu r.es tance is atop priority a; CIMMYT. rose by 66 percent, while acreage This organization has a cooperative increased by 33 percent and yields breeding program with six national by 24 percent. However, on an indi- maize programs (Thailand, the vidual- country basis, only about Philippines, Tanzania, Zaire,

half the developing countries have Nicaragua, and'El Salvador) to de- made significant gains (1979 CIMMYT velop resistance to downy mildew Annual Report). The bulk of adap- (important in Asia and spreading to tive research work with maize in the other regions), maize streak virus developing countries has occurred in (Africa), and corn stunt virus certain aren- of Latin America. (tropical Latin America). Africa and Asia, however, have Maize Production Achievements location-specific growing problems The.Puebla Project in Mexico in terms of soils, climate,insects, was the'first large-scale attempt And diseases for which varieties to improve small-farmer maize and improved r- actices still must production. be developed. The CIMMYT is pre- Under CIMMYT administration, sently cooperating with national the project involved 47,000 farm maize prograks in Tanzania, Zaire, families in a highland region of Ghana, Egypt and Pakistan as well Puebla State. Average farm size in .3as Guatemala and is providingstaff the project area was 2.7 ha, operating support- to most of them. In adak, mainly under dryland (non-irrigated) tion, it co4erates on a regional1. conditions. Several "packages" of basis with Central America and the improved practiced were developed to Caribbean, South and Southeast suit varying climatic and soil condi- Asia (11 countries), an the Andean tions in the zone, and adequate zone (Bolivia, Colombia, Ecuador, support and delivery systems were

80 p v O

sought for the needed inputi, the cooperating countries to run 'including agricultural credit. By extensive trials on farmers' fields 1972, maize production bad increased rather than confining them to the in the project area by some 30 per- experiment station where conditions cent.and average familyincome had are often unrealistically ideal. increased by 24 percent in real On the Horizon: Scientists have

terms. Rural employment was also ' been working on breeding a nitrogen- favorably affected due to an, fixing ability similar to that of legumes into maize. By 1985, they increase in labor needed for every hectare of maize. hope to have experimental varieties The Puebla Project was inno- capable of satisfying ap, to 10 per- vative in movirg the "Green Revolu-. cent of their nitrogen requirements. tion" (the first organized attempt to develop yield ftproing practices Grain Sorghum for staple food crops in developing countries) off the experiment sta-, 'Potential for Improvement tion and into the field and in con- Yields of grain sorghum are centrating on dryland rather than generallytnot as spectacular as irrigated farming. those of maize, since the crop is Similar examples exist in often grown under less than ideal many other developing countries: conditions. Sorghums advantage Experimental plots frequently yield over maize is its much better yield over 6000 kg/ha and it is generally stability over a wider range of agreed that 30d0 kg/ha or more 4s a climatic conditiond, especially reasonable yield goal for small under high temperature and low rain- farmers in most regions. Since fall. Many of the traditional the real test of an improved variety varieties in the' semi -arid tropics is its pertormance under actual'farm are overly tall, are photosensitive, conditions, CIMMYT is encouraging and have an excessive ratio of stalk

81 89 and leaves to grain. Their delayed therefore need good head mold resis- flowering enabled them to escape tance for maturing under more humid serious grain head mold problems conditions.Plant height would be and insect damage, but often there about 2.0-2.5 meters with a better is too little soil moisture for ratio of grain to stalk and leaves. grain deVelopment which takes place Since sorghum plants are an impor- at the start of the dry season. tant livestock forage in much of the These factors, along with poor semi-arid tropics dwarf varieties like management and the large plants' those used in the U.S. would not be intolerance to healthy plant acc able. The new varieties would densities (populations), account for mature in 90-120 days. low yields averaging around 600-900 Also under consideration are kg/ha in the semi-arid tropics. plants with heavy tillering ability Current Research Activities and to allow compensation for low plant

Crop Programs . populations and a variety with resis- The International Crops Re- tance to strias (a serious parasitic search Institute for the Semi-arid -weed, see Chapter 6), sorghum midge, Tropics (ICRISAT), located in sorghum shoot fly (see Chapter 6) Andhra Pradesh,'India, is the major and drought.Work is also being international institute engaged in done to develop more cold - tolerant sorghum improvement. Some ofcits varieties for highland or cool- major goals include the development season tropical conditions, and of varieties with little or no plants with improved disease resis- photosensitivity.These varieties tance, especially to downy mildew, would have a shorter growing season charcoal rot, smuts, anthracnose, and be better adapted for drier areas and' rust (see Chapter 6). Finally, or shallow soilswith lowwater hold7 the institute hopes to develop a 'ins capaaLy. They would be planted. hi-lysine and higher protein sorghum later, but flOwer about two weeks 'that has better cooking quality and earlier than traditional types and palatability.

82 Spreading Improvement Practices tional typeswere discoveredin for Sorghum Ethiopia. However, these lines In the southern savanna suffer from some of the samedraw- region of West Africa, improved photo - backs as hi-lysine maizein that cgensitiVe varieties have yielded over the grain has a softstarch, 3500 kg/ha in 120-140 days, some two flopry endosperm (themajor portion months less than local varieties. of the seed surroundingthe germ They can be sown later in the wet [embryo)) that is verysusceptible season and will flower about 8-14 to storage insectsand to breakage days earlier than the local types, under grain threshing usinganimal Also, studies have shown thus assuring better moisture avail:- trampling. lenity for grain filling. these extra proteinvi)enefits to As of yet, highly photoin- vary greatly underdifferent envi- sensitive (day neutral) varieties ronmental conditions. Forexample, with good head mo111resistance have low soil nitrogen content can cause not been developed. There are both the lysine and protein percent- improved types of this class that age to drop tonormal levels. It are available with 90-120 day ay be 1985 or laterbefore such maturities, but their planting must improved nutrition varieties are be scheduled late enough in the released. wet season so that the grain fill Nitrogen-fixing ability: As period occurs at the start of the with maize, attempts to breed some dry season to avoid head mold. nitrogen-fixing ability intosorghum This, however, subjects them to are only in theearly experimental probable moisture stress. stages. Improvements in sorghum Production improvements and protein: In 1974, two lines of sor- the future: Sorghum lags behind ghum with 30 percent more protein maize in successful on-farmyield and double the lysine of conven- improvement campaigns. Most sue - 0

83 91 rV

cesses have occurred in:the less photosensitive types often flower marginal rainfall areas. For example -too late in the season, causing although high - yielding sorghum vari- moisture stress during grain eties were releasisl in India in t1.4 filling.Those varieties which mid -fly s, they spread little beyond are not as affected by daylength regions with assured rainfall or (the Geros) have moderate tilletling irrigation. A major factor is the ability, but-it is not synchronous highly variable climatic environment with the main stem. Thus, most of of the semi-arid topics where stan- the tillers flower too late, when dardized technology packages have moisture is not adequate for grain only limited suitability, thus re- filling. quiring greater adaptive research Current Research Activities and efforts. However, organized efforts Crop Problems at sorghum improvement are much The ICRISAT breeding program more recent than those for maize, concentrates mostly on pearl millet, and the future does look promising. and it aims at improved drought, Millet insect, and disease-resistance, increased response to improved prac-

Potential for Improvement tices, better harvest index, and Millet yietds are generally varieties with a range of maturities lower than those of sorghum due to to suit varying rainfall patterns. a harsher grqwing conditions and a It is selecting also for varieties shorter period of grain filling. particdlarly suited to intercropping Traditional West African varieties combinations. Protein'content and have major limiting factors such as early seedling vigor are other poor plant architecture.They tend concerns. to be overly tall and have a poor In West Africa and the Sudan harvest index.) In addition, the ICRISAT has a program to develop

84 92. high-yielding sorghum and millet (Sclerospora graminicola), a serious varieties. This cooperative program fungus disease encouraged by high. includes the countries of Mali, Upper humidity. As with maize and sor- Volta, Niger, Ghana, Chad, The Gambia, ghum, attempts are being made to 4 Senegal, Nigeria, Mauritania, develop some limited nitrogen - fixing Cameroon, and Benin. ability in millet, but results Achievements in Millet Improvement are at least four to five years As with sorghum , millet away. improvement efforts in the developing On the Horizon:,Millet pro- IP countries are relatively recent and duction should expand significantly at an early stage. The ICRIgAT in the future as more marginal trials in West Africa during 1976 rainfall land is brought under and 1977 showed that new varieties cultivatioh. Further research is were not much better than the exist- expected to make the millets one of . ing West African types with a few the most productive cereals on a exceptions. The major problem was yield per area per time basis (yield lack of disease resistance and over- of crop in a certain area per crop- _ ly early maturity. On the other ping cycle per year). hand, breeding efforts in Senegal have produced high-yielding dwarf Peanuts types capable-of better fertilizer response. These'have an improved Potential fur Improvement harvest index and a maturity .:singe When grown under ideal mois- of 75-100 days. Some of the best ture conditions, peanut and other ICRISAT varieties have yielded up pulse crop yields arebout one-third to 4000 kg/ha in international to one-half those of maize. However, trials. Progress also is being since peanuts are about three times made in the-development of varieties higher in protein than maize, the with good resistance to downy mildew yields are actually very similar on a as-

85 3 tein per area basis (a 2000 kg/ha pea-. Most'efforts concentrate on collect-

f nut crop produces about the same total ing and improving local and intro- amopnt-of protein as a'6000 kg/ha duced varieties by selecting for maize crop). This is also the case adaptability, drought resistance, with the other pulses, all of which .oil and protein content,. disease

have two to three times more protein and insect resistance; and shelling u than the cereals. In short, the pulses percentage (ratio of shell weight are geared more to producing modest to kernel weight). / yields of high protein seed rather Spreading Peanut Improvement than high yields of starchy seed as ActivitieS with the cereals. Although the The major international lower yields of the pulses should be institute involved' with peantit kept in mind, there is potential for improvement in the deVeloping

yield improvement in the developing countries is ICRISAT.' Advanced countr s where production per hec- work is also being done in several tare 11is considerably behind that of of the developed countries sure as the 'developed countries. the U.S. (especially Georgia; North Research Activities and Crop Carolina, and Texas), Australia, Improvement and South Africa, butit is-designed Since peanuts areiself- to serve their local conditions. pollinated, the development of new Other centers of peanut improvement varieties by crossing is difficult are Senegal,,Nigeria, the Sudan,' and time-consuming.The individual Mexico, Argentina, and Brazil. flowers must be manually emasculated Breeding for earliness to and then hand pollinated. Since seed suit short rainy seasons, seed production per plant is comparatively dormancy (to prevent in-ground low, multiplication of improved sprouting), and resistance to rust, f types is very slow, althoughthey' leaf spot, and aflatoxin.(see Chapter

can be propagated by cuttings. 6) are all being conducted by

94 q ICRISAT. Work in Senegal has devel- seed, 'fertilizer and other inputs.

oped several lines resistant to . Under these conditions, adaptive rosette virus, a serious problem in research work id also given greater the wetter peanut zones of Africa. priority, but the weak link is also Of the reference 'crops, pea- the extension system, which must nuts are the most complicated in bridwarthe between the farmer terms. of growing and harvesting prac- and'tlieexperiment station. In gen-. ticed needed tor good yields. Seed- eral, yields are far below' the bed preparatidn, weed and disease '1700-300 kg/ha range that is fea- conprol,-and Harvesting require sible under improved practices particular attention to detail and where moisture stress is not ser- timeliness. Being a much higher ious. value,crop than the cereals, repeated applications of foliar fungicides for leafspot control Beans and Cowpeas

have a good cost- benefit ratio and are another example of the relatiVe Until the early 1970s, pulse

ts sophisticatilriquired for good 'improvement had been largely yields. Unddubtedly, plant breeding neglected. Compared to the cereals,

has a rolet play in peanut improve- theie.grain leguies seem4d to offer % ment, but im roved management prat- less'promising oppOrtunities duei: .tices are palticularly important for to their relatively low yields and , boosting yies. greater susce tihlity to insects In t se developing coun- . anddihaies.However, in view of tries where eariuts are a major!; -their H'igh protein contents and export crop, arketing is usual* pot'anvialliasnutritional cPie- 'controlled by a government board; mints to ithe cereals, rese7ch1 and . i which also pr vides storage ension programs can no /longer I / ties and may 1:)pot as a supplier'of. A afBora to ignore them.The best

87 /' 95 yields of the Cereals and the pul- improvement is CIAT. In 1973 they ses are fairly similar when rom- established a Bean Production Sys-

pared on a protein produced Ver terns Program to increase the ' area basis. production and consumption of the Common Beans crop in Latin America. in addition Potefntlial for Improvement it also cooperates with developing Early research seemed to sug- countries in other areas.This gest'`that common beans were one of effort is now being supplemented the lbast productive of the pulses. by a recently organized U.S. govern- However, a comparative growth study ment-sponsored program for coopera- by the International Center for tive drybean/researchbetween 8 Tropical Agriculture (CIAT) in U.S.universitiesand developing 1978 involving'five grain legumes countries. showed that common beans and cow- TheTAT program aims to

' peas were the two most efficient on increase bean yields through imp-, ayield per day of growth basis (the eral methods: :other three involved were pigeon- Development of improved

varieties resistant to . peas, soybeans, and piling beans). major diseases and several stress factors like low; Unfortunately, current soil phosphorus, soil aCid7 average:yield fdr Africa and Latin ity, drought, and temperature extr es. Special America are a low 600 kl/hav attentio is being given to while! CIAT has obtained up, to4300 mixed cr in with maize.

kg/hajunder monocrOPping(teans as Breeding for improved nitro-

the SoiecropY and-3000 kg/ha in ctILI gen fixation, Currently, common beans are one of the mixed plantings with maize. more inefficient nitrogen fixers and require moderate, Current Research Act.ities and 1 rates of supplemental CrapPrograms . fertilizer. / The Ma] r in ',Developing improved manage- institute inv lved incommon,bean Trent practices for both

88 ICRISAT. Work in Senegal has devel- seed, fertilizer and other inputs. oped several lines resistant to Under these conditions, adaptive rosette virus, a sellous problem in research work is also given greater the wetter peanut zones of Africa. priority, but the weak link is also Of the reference crops, pea- the extension system, which must nuts are the most complicated in bridge the gap between the farmer terms of growing and harvesting prac- and the experiment station. In gen- tices needed for good yields. Seed- eral, yields are far below the bed preparation, weed and disease 1700-300 kg/ha range that is fea- control, and harvesting require sible under improved practices particular attention to detail and where moisture stress is not ser- timeliness. Being a much higher ious. value crop than the cereals,: repeated applications of foliar fungicides for leaf spot control Beans and Cowpeas have a good cost-benefit ratio and are another example of the relative Until the early 1970s, pulse sophistication required for good improvement had been largely yields. Undoubtedly, plant breeding neglected. Compared to the cereals, has a role to play in peanut improve- these grain leguMes seemed to offer ment, but improved management prac- less promising opportunities due tices are particularly important for to their relatively low yields and boosting yields. greater susceptiblity to insects In tho'e developing coun- and diseases. However, in view of tries where peanuts are a major their high protein contents and export crop, marketing is usually potential as nutritional comple- controlled by a government board, ments to the cereals, 'research and which also provides storage facili- extension programs can no longer ties and may act as a supplier of afford to ignore them.. The best

87 97 4 yields of the cereals and the pul- improvement is CIAT. In 1973 they ses are fairly similar when com- established a Bean ProcAction Sys- pared on a protein produced per tems Programto increase the area basis. production and consumption of the Common Beans crop' in Latin America. In addition/ Potential for Improvement it also cooperates with developing Early research seemed to sug- countries in other areas. This gest that common beans were one of effort is now being supplemented the least productive of the pulses. by a recently organized V.S. govern- However, a comparative growth study ment-sponsored program for coopera- by the International Center for tive dry bean research between 8 Tropical Agriculture (CIAT) in U.S. universities and developing 1978 involving five grain legumes countries. showed that common beans and cow- The CIAT program aims "to peas were the two most efficient on increase bean yields through sev- a yield per day of growth basis (the eral methods: other three involved were pigeon- Development of improved varieties resistant to peas, soybeans, and mung beans). major diseases and several stress factors like low Unfortunately, current soil phosphorus, soil acid- averaee yield for Africa and Latin ity, drought, and temperature extremes. Special America are a low 600 kg/ha, attention is being given to while CIAT has obtained up to4300 mixed cropping with maize. (beans as kg/ha under monocropping Breeding for improved nitro- the sole crop) and 3000kg/ha in gen fixation. Currently, common beans are one of the mixed plantings with maize. more inefficient nitrogen Current ResearchActivities and fixers and require moderate rates of supplemental Crap Programs fertilizer. The major international Developing improved manage- institute involved in commonbean ment practices for both

88 98 O

ICRISAT.. Work in Senegal has devel- seed, fertilizer and other inputs. oped several lines resistant to Under these conditions, adaptive rosette virus, a serious problem in, research work is also given greater the wetter peanut zones of Africa. priority, but the weak link is also Of the reference crops, 'pea- the extension system, which must nuts are the most complicated in bridge the gap between the farmer terms of growing and harvesting prac- and the experiment station. In gen- tices needed for good yields. Seed- eral, yields are far below the bed preparation, weed and disease 1700-300 kg/ha range that isfea-. control, and harvesting require sible under improved practices particular attention to detail and where moisture stress is not ier- timeliness. Being a much higher ious. v' value crop than the cereals, repeated applications of foliar fungicides for leaf spot control Beans and Cowpeas

have a good cost-benefit ratio and are another example of the relative Until the early 1970s, pulse sophistication required for good improvement had been largely yields. Undoubtedly, plant breeding neglected. Compared to the cereals, has a role. to play in peanut improve- these grain legumes seemed to offer ment, but improved management prac- less promising opportunities due tices are particularly important for to their relatively low yields and boosting yields. greater susceptiblity to insects In those developing coun- and diseases. However, in view of tries where peanuts are a major their high protein contents 'and export crop, Iharketing is usually potential as nutritional comple- controlled by a government board, ments to the cereals, research and which also provides storage facili- extension programs can no longer ties and may act as a supplier of afford to ignore them. The best

87 93 yields of the cereals and the pul- improvement is CIAT. In 1973 they ses are fairly similar when com- espablished a Bean Production Sys- pared on a protein produced per tems Programto increase the area basis. production and consumption of the Common Beans crop in Latin America. In addition Potential for Improvement it also cooperates With developing Early research seemed to sug- countries in other areas. This gest that common beans were one of effo(t is now being supplemented the least productive of the pulses. by a recently organized U.S. govern- However, a comparative growth study ment-sponsored program foi, coopera- by the International Center for tive dry bean research between 8 Tropical Agriculture (CIAT) in U.S. universities and developing 1978 involving five grain legumes countries. showed that common beans and cow- The CIAT program aims to peas were the two most efficient on increase bean yields through sev- a yield per day of growth basis (the eral methods: other three involved were pigeon- O Development of tmproyed varieties resistant to peas, soybeans, and mung beans). major diseases and several stress factors like low Unfortunately, current soil phosphorus, soil acid- average yield for Africa and Latin ity, drought, and temperature extremes. Special America are a low 600 kg/ha, attention is being given to while CIAT has obtained up to4300 mixed cropping with maize.

kg/ha under monocropping (beans as Breeding for Improved nitro- the sole crop) and 3000 kg/ha in gen fixation. Currently, common beans are one of the mixed plantings with maize. more inefficient nitrogen Current Research Activities and fixers and require moderate rates of supplemental Crop- Programs fertilizer. The major international Developing improved manage- institute involved in common bean ment practices for both

88 100 monoculture and mixed cropping a damaging species of leafhopper systems (see chapter 4). (Papoasca Kraemeri) prevalent in Training personnel from national programs in other Latin America. Strains were found developing countries and also that showed some tolerance to developing a strong bean research network in Latin low levels of soil phosphorus and America and East Africa. to aluminum and manganese toxicity As part of its in which often affects bean in highly trials program, CIAT maintains acidic soil (much below pH 5.5). Both CIAT and.CATIE have made signi- an International Bean Yield and ficant progress in improving bean- Adaptation Nursery (IBYAN), con- maize multiple cropping systems sisting of 100 entries., This IBYAN through improved management and is replicated by CIAT and shipped bean variety development. to many other countries to be used Due to the relatively recent in their experimental work with interest in bean research, on-farm beans. The Center for Tropical yield improvement programs have made Agriculture, Research, and Training nowhere near the impressive and (CATIE) in TUrrialba, Costa Pica widespread gains of maize, rice, also is involved in bean improve- and wheat. However, research ment work. achievements in breeding and Spreading tean Improvement Practices management are at the point where After neatly some five years farmers can increase their yields of breeding work, most 'of the im- with a well-organized extension , proved varieties CIAT sent out for program. international trials in 1979 carried some resistance to major pest problems like common mosaic virus, rust, common bacterialblight, angular leafspot, anthracaose, and

89 -.101. Cowpeas

ProEress in Cowpea Improvement The International Institute for Tropical Agriculture (IITA) in Nigeria is the major international institute involved in cowpea improvement and is working toward good pest resistance, improved yields. and the development of a package of improved practices for cowpeas under multiple cropping conditions common in trop- .4 ical Africa. By 1978, IITA had released a total of five new strains (VITA 1-5) with better yield and pest resistance and a good protein content. They .are capable of producing 1500-2500 kg/ha under small-farmer improved management, compared to the current4West African average of around

500 kg/ha. The creamy white seed color of VITA 5 is favored in much of Africa. As with common beans, on-farm yield 0 improvement extension efforts are still in their early stages.

102 90 6: 4. Planning and Preparation

This chapter deals with refer- ronment and specific infra'structure. ence crop production fundamentals and current recommendations concerning cropping systems, land preparation, seed selection, and plating. The Cropping Systems production fundamentals section describes the' howl, what, anewhy of these farm operations. The compendium section provides a current sum-. As explained earlier, the term mary of reference crop, production "cropping system" refers both to a recommendations based largely on farmer's or r \gion's overalrIgropping information from international pattern, and to the specific crop researchanstitutes and some national sequences and associations involved, extension services. Although the ntely:

. compendium section does offer gen- 1. Monoculture: The repetitive growing of a single crop on the eral suggestions for the various same field year after. year. crops, agriculture is a Iodation- 2. Crop Rotation: The repetitive specific endeavor. This section is growing of an orderly succession of crops (or crops alternating mainly designed to show how recom- with fallow) on the same field. mendations vary according to differ- 3. Multiple Cropping: ences in each area's- physical envi- a. Sequential cropping: Growing

91 103 4)

two or more crops in succes- agroriimically. sion on the same field per - year or per growing season, sometimes referred to-as Monoculture vs. double or triple cropping. Crop Rotation Example: Planting maize in May, harvesting it in Auguit, and then planting beans. It is difficult to compare Only one crop occupies the field at a time.. the pros and cons of monoculturever- b: Intercropping: This is the sus crop rotation since much depends most common definition of On the crops, soils,Juanagement prac- multiple cropping and involves growing two or tices, climate and economics more crops at the same time involved. Monoculture is frequently on the same field. There are four basic variations; blamed for soil "exhaustive (erosion Mixed intercropping: Two or problems and declining fertility and

more crops without a dis: . tilth) and a buildup of insects and tinct row arrangement. Row intercroppirs: Same as diseases, yet this is not always the nixed intercropping but case. Some very productilie areas of with a distinct row the U.S. Corn Belt have over 50 per- arrangement. cent of their cropland devoted to con- Relay intercropping: Grow - ing two or more crops simul- tindbus maize,,,which yields as well taneously during part of as Chat grown under crop rotation. the life cycle of each. The second crop is usually In fast, Corn Belt research has sown after the first has shown that continuous maize grown teached its reproductive stage (i.e., around flower- under that regior0,s conditions -ing time) but before it is' results in a less serious insect ready to harvest. Example: Planting a climbing bea# buildup than when maize is grown in variety alongside maize a crop rotation with soybeans or peg- that has recently tasseled. ( ture and hay. On the other hand, /' Strik intercropping: Growing two or more crops in separ- monoculture cotton in the southern ate strips wide enough for U.S. in the 19th and early 20th cen- independent cultivation, but narrow enough to react turies led to serious soil degrade- ,

92 104 4:1

4 4 tion and insect problems. matter ,(humus)* content:. Monocultureis uncommon Row crop monoculture will seriously lower soil humus lev- under small farmer conditions in els unless all crop residues ,developing countries, since intercrop- are returned to the soil along pint is 'prevalent and a variety of with supplemental additions of manure in sizeatle amounts crops must be produced for-subsis- (around '30 metric tons/ha or tence needs. It is mainly confined more per year). fhe'tillage and cultivation to perennial cash and egport crops operations associated with such as coffee, sugarcane, citrus, mechanized (or animal trac- and bananas. Whether or not monocul- tion) row crop production aereate the soil, which ture is harmful depends on the type accelerates the microbial of crop and soil management and cli- breakdown and loss of humus. That is part of the reason mate factors. why many farmers in the U.S. Type of crop: and Europe have switched to minimum tillage systems,such Row crops which provide rela- as plowing and planting in tively little ground cover or one operation.Minimum til- return only small amounts of lage leads to problems with residues (stems, leavest weeding and herbicidal use. branches and other debris The problem of humus loss 'is' left in the field after har- especially serious in the /7 vest) ro the soil are poorly tropics due to higher temper- suited to monoculture (i.e. atures. Decompiosition takes ebtton, peanuts, maize or sor- place three times as fast as ghum grown for fodder or sil- 32°C than at 15.5°C. age). Erosion problems associated Some crops like beans, pota- 'with row crops are more ser- toes, and many vegetables ious in the tropics due to are especially prone to higher intensity 'rainfall insects and soil-borne dis- (even in semi-arid areas). eases which usually build up under monoculture. ' Crop rotation may or may not Soil Manakement and Climate Factors: be beneficial in terms of soil A soil's physical condition (tilth--- and.permeability), natural fertility, and nutrient-holding ability are *Humus is organic matter that has directly related to its organic been fairly well decomposed.

93 103 Alf

4 condition, insects, and diseases. Suggisted Crop Rotation for the Reference Crops in terms of soil condition, the ideal would be to,. ratate low-resi- The yatiablesare too great to due crops like,ccitton and vegetables mak.e specific recommendations of wide with medium-residue crops like corn, applicability. Much depends on the sorghum and rice or, better yet, area's soils, climate, prevalence with pasture, but few small farmers and type of intercropping, and com- can afford this type of flexibility. mon insects and diseases. Including a nirrgen-fixing'legume Some general recommendations crop like peanuts or beans.in the can be made: rotationvill not necessarily boost Crops which share similar diseases (especially soil-borne the soil's nitrogen content signifi- ones like root rots) should cantly, since much of the nitrogeg not be.grown on the same field within three years of each produced ends up in the harvested other. For example, peanuts,' seeds themselves. Some areas have tobacco, beans, soybeans, and sweet potatoes are all suscep- experimented with green manure (leg tible to Southern Stem Blight ume) crops like cowpeas, which are (Sclerotium rolfsii), as well as to the same types of nema- plowed under around flowering time todes, and should not be to add humus and nitrogen to the grown on the same' field in succession. soil (no harvest is taken}, but 10. A crop like peanuts or beans there are several problems with this which is especially suscepti- approach: ble to soil-borne diseases should not be grown on the Few farmers ate willing to same field more than one year tie up their land growing a out of three. Again, inter- non - harvested crop. cropping may lessen these The effect of green manure problems, but not always. crops on soils is short-lived Monoculture is less of a prob -' under tropical. conditions. lem if disease-resistant vari- The green manure cropmay use eties are available and are up soil moisture needed by being continually developed the next crop. in response to new disease strains.

.94 106 .

. reduced efficiency in planting, Intercropping Ob. (Multiple Cropping) weeding and harvesting'. The type of muliple cropping is closely relattd to rainfall and

. . Intercropping combinations. length of rainy season as shown . below: involving two or more of the refer- Prevalent Type of ence crops (soinetimes along with Annual Rainfall Multiple Cropping

others) are very common onsmall Simultaneolis mixed . . . intercropping with farms in the developing world. crops of similar Intercropping is not 60inar- 300-600 mm maturities t' ily suited 66 mechanized farmitig, Crop mixes of dif- t 600 -1000 mm but strip intercropping is sometimes ferent maturities used when'multiple-row machinery Three types of mul-' tiple cr9pPing: can be oper'a'ted. sequential, simul- . Over 1000 mm taneous, and relay The Pros and Cons of Intercrepping Pros Advances in Less risk since yields do not Intercropping depend on one crop alone. Systems Better distribution of labor. 1 Some diseases and insects -/Multiple cropping is a diverse' appear to spread less rapidly under intercropping. and complex subject whose guidelines Better erosion control due to are often very location-specific. better grouild cover. Research interest in multiple crop- Any legumes involved may add ping has increased. markedly over the, some nitrogen to' the soil. past decade with most attention being Cons focused on cereal-legume combinations Mechanization is difficult. which appear to have the greatest Management requirements are highey. potential, particularly maize or sor- Overall costs per unit of pro- ghum with beans or cowpeas. duction may be higher due to The following research results

.Tr 95 107 C I

are presented not to imply their next under humid conditions. direct applicability to a given area . Even though legumes used ak but to provide ideas of the many fat- grin manures may contribute a good deal of soil nitrogen, tors involved in inter cropping and farmers are still likely to the state of the :rt of these complex need fertilizer, since leOmes. will not do well on the low-. :systems. phosphorus soils prevalent The National Maize Program in throughout much Of .the tropics. Zaire has been lookiriginto mai Pearl millet-peanut intercropping

rotations and intercropping with . trials by the international Crop legumes to improve soil fertility Research Institute for the Semi-Arid without commercial fertilizer. Rota- Tropics (ICRISAT) in India showed tions using soybeans and Crotalaria yield advantages of up-to 25-30 per-s (a green manure crop poisonous to cent. An arrangement of one row-mil- livestock) have been tried. So far, let to three rows peanuts appeared Crotalaria looks supe'rior in nitro- to provide the optimum balance of . gen-fixfrg ability with the succeed- coMpetition. ing :rop, yiepir2 up to 9000 Maiie-Bean Intercropping Research: kg/ha. Maize followirig.a soybean The International Center green manure crop has yielded up to for TroPEcal:Agriculture (CIAT) has 6700 kg/ha..The.National run nume:aus maize-bean-Intercrop-

- cram has also worked with an intercrop ping trails at various locations in combination o f cowpeas and 'maize, but Colombia. The trials involve simul- has not yet found suitable cowpea taneous or near-simultaneous plant- varieties. 'ing of the two crops rather than Both rotations and intercrop- relay planting. Results were as fol.-. ping of maize. with legumes appear to lows: offer some promise in .Zaire, but 0...Por the farmer, the optimum ratio of maize plants to bean there are two main problems: plants depends not only on Legume seeds are harder to the relative yields but also A store- from one year:tb the on the maize-bean price ratio

96 106 6

which ranges from from 1:2 up to a 1976 Center for Tropical to 1:7 in some Latin American AgricultureResearch and Training countries. A large number Of trials (CATIE) trial in Costa Rica, inter - involving simultaneous or cropped populations of 50,000/ha for near-simultaneous plantings. of maize and 200,000/hs for bush beans maize with beans showed that bush bean yields were were found to be tie best combination decreased by about 30 percent.. and produced yields of 3400 kg/ha and and climbing bean yields about 50 percent compared"to when 1800 kg/ha respectively. grown alone.' A 1976 study in the Minas Ger- Maize yields were usually not ais area of Brazil by the Universi- adversely affected by the association with beans at a dade Federal de Vicosa focused on maize'population of 40,000 relay intercropping of maize and plints/ha. Maize plant densities over 40,000/ha decreased beans. Maize.populations of 20-, 40- bush bean'yields by shading, and 80,000 per hectare were inter-. while densities below 40,000/ ha lowered,climbing bean cropped with climbing beans at 100-, yields because of inadequate 200-, 300- and 400,000 plants/ha. support. The maize was planted in the wet sea- At 40,000 maize plants/ha, relative yields of the two son, and the beans were planted crops were bestat bush bean between the-mforre rows when the maize -densities of 200-250,000 plants/ha and at climbing was nearing maturity. The,Jollowing bean densities of 100-150,000 results were obtained: 'plants/ha. Maize yield was not affected Yields of climbing beans were by the beans'and was-highest highest when they were planted at 60,000 plants/ha. simultaneously with maize; bush bean yields were highest Bean yields were highest at when the beans were planted the lowest maize population one to two weeks'before maize, and were not affected by bean although this caused a sftni- plant density. ficant yield decrease in the s Even though the beans were maize. Results varied with planted as the maize was start- temperature and the relative ing to dry out, the maize early vigor of the bean and still exerted a strong compe- maize seedlings. titive effect, mainly due /

97 109 e

shading. When grown alone and sorghum once the rains arrive under trellising, the bean without regard to where the yet-to- variety normally yielded i 1200-2000 kg/ha at a density germinate beans are. With the local of 250,000/ha, but yielded varieties used, if the beans emerge 800 kg/ha when grown with a maize population of 20,000/ha. first, they will dominate the maize Cowpeans-Millet-Sorghum: Experience and sorghum; the reverse will happen in Africa has shown that cowpea if the maize and sorghum germinate yields are reduced about 45-55 per- first. Hoping for a balanced harvest, . cent when intercropped with millet the farmers are in a race agains time and sorghum. However, when grown to finish planting the maize and sor- alone, the improved cowpea varieties ghum before the beans germinate. ,The become more prone to serious insect main disadvantage of this traditional attack and often require chemical system is the risk that the dry- pest control. Furthermore, interplanted beans may receive only enough cropped cowpeas are not usually sown rainfall to germinate without suffi- until later in the wet season and cient additional precipitation to are viewed more as a bonus crop sustain growth (i.e., a wet season which does not reduce the millet and "false start"). sorghum yields. Researchers have experimented Improving Traditional with several alternatives. The most Multiple Cropping Systems promising one involves strip inter- In .southeast Guatemala, small cropping of maize, sorghum, beans farmers usually,plant maize, sorghum, and cowpeas. and beans by hand on steep to rolling At the start of the wet sea- rocky land, and yields average around son, beans are planted in strips con- 530, 630 and 410 kg/ha respectively. sisting of three rows spaced 30cm Due to a severe labor shortage for apart. Sufficient space is left planting at the start of the season, between these strips to accommodate the,farmers plant the beans in dry sets of double (twin) maize rows with soil. They then uverplant the maize two "varas" (164.0 cm) between the

98 1 4

centers of the twin rows. Two or grain rots) and reducing bird mure of these twin row sets of damage. maize can be planted between bean About two weeks before the strips depending on the desired maize is doubled, cowpeas are sown cropping mixture. The 30 cm bean row along the outer edges of the twin spacing is unusually narrow but gives maize rows (i.e., along the edges of better weed- control due to earlier the harvested bean strips). The inter-row shading. Also, the strips leaves of the maize plants are are narrow enough to be hand-weeded stripped off as they die off with matur- from the sides to avoid soil compac- ity and used as a mulch (soil cover- tion or trampling the plants. ing) to conserve soil moisture. The Once the beans emerge, the cowpeas use the maize stalks to maize rows are planted. If the climb on and cause no'competition rains ,top for a while after bean due to their late planting. planting, maize sowing can be delayed without danger of the beans Shifting Cultivation dominating the young maize seedlings As a Cropping (one advantage of strip intercrop- System ing). The beans are a short season variety that matures in 60-65 days. Shifting cultivation (slash and As soon as tb.a beans are burn agriculture) is a traditional harvested, a short season sorghum cropping system that was once widely variety is planted in the space practiced throughout the humid trop- between the'sets of twin maize rows. ic:;. Due to increasing population Later, the nearly mature maize plants pressure on land, the system is now are doubled over to reduce any shad- mainly confined to the dense forest ing of the young sorghum plants, areas of the Amazon Basin; Central which are slow starters. This points and West Africa, and Southeast Asia. the ear tips downward, preventing While there are some varia water entry (which favors fungal tions,shifting cultivation consists

99 lid. of three major steps: fallow for 5 -10 years in order to "rejuvena4e" the soil in 1. The land is incompletely cleared by hand cutting and burning trees several ways: and other vegetation. The burn- The vegetation, especially if ing has several effects: it consists largely of trees .All the vegation's nitrogen and other deep-rooted species, and sulfur is lost to the recycles leachable nutrients atmosphere as gasses. However, like nitrogen and sulfur that the other nutrients (phos- may be carried into the soil phorus, potassium, calcium, by rainfall during the crop- etc.) are deposited on the ping and fallow periods. ground as ash. Some of the fallow vegetation may be leguminous and actu- Even though much organic mat- ally add nitrogen to the soil. ter is lost, a lot has already been added to the The fallow increases the amount of soil humus which is soil over the years by leaf a vital storehouse and source fall and root decomposition. of nutrients, as well as Burning only kills some being a great improver of insects, diseases, and weed soil physical condition. seeds, not all of them. Small, but significant, 1. Crops are grown on the ldnd for amounts of nitrogen are pro- two or three years, usually duced by lightning, and these under some form of intercropping are added to the soil by 'asso- that may include long-cycle ciated rainfall. 'crops such as manioc (cassava) The fallow period also helps and yams in humid regions. Little, if any, tillage (hoeing, avoid a buildup of pests and diseases. etc.) is required for seedbed Shifting cultivation requires no out- preparation, since the soil is usually in good physical condi- side inputs and is in complete har- tion as a result of the previous -mony_with,the natural environment of fallow. The crops utilize the naturally accumulated nutrients the humid tropics. However, the from the fallow period. Yields system's success depends heavily on are fair the first year, but then rapidly decline, causing maintaining an adequate length of the land to be temporarily As the frequency of abandoned after several years of fallow cycle. cropping. clearing and burning increases, trees

3. The'land is then allowed to and brush are eventually killed off revert to a natural vegetation and give way to a very inferior grass

100 112 (savanna) fallow, which is shallow- Listed below are some of the rooted, inefficient at recycling and most promising possibilities for accumulating nutrients, and very dif- improving shifting cultivation: ficult to clear off for cropping. The "Taungya" system of Bur- (Many tropical grass species are mese origin involving agriculture and forestry; it basic- actually stimulated into dense ally consists of clearing regrowth byburning.) Under these land for a cropping cycle followed by planting fast-grow- conditions, slash and burn agricul- ing trees to provide lumber . ture becomes a menance to the envi- and rural improvement. Both phases would be operating ronment, causing severe deforesta- 4 simultaneously within an area. tion, erosion, and soil exhaustion. Using fertilizers (chemical Many areas of Central America have or organic) to increase yields during the cropping period. been denuded in this manner. Seeding the fallow area with Improving Shifting Cultivation: specially selected plants that As explained, the system is may be more beneficial than the nataral species; the basically suited only to the humid improved fallow might include tropical' forest zones under low dense growing vining legumes or leguminous trees and population density. European shrubs. attempts to replace shifting cultivation in parts of Africa with "modern" agriculture usually met with Land Preparation disaster (erosion, pests, diseases, and a serious decline in soil con- For Cropping dition). Some tropical soils have an iron-rich laterite layer which may become exposed through erosion. . Unless such soils are kept under con- On small farms, land prepara- tinuous shade, the laterite can tion methods for the reference crops harden irreversibly, making them use- may or may not involve actual till- less. age (working the soil with hoes,

101 1 1 ? plows or other equipment) or seedbed left on the surface to form a mulch (a. protective covering). shaping (leveling land or making The seeds may be planted in raised beds or ridges). the ground or may'even be scattered over the ground before slashing. The mulch is valuable for erosion and weed con- Methods Involving . No Tillage or trol, conserving soil moisture, 10 Seedbed Shaping and keeping soil temperatures more uniform. The Interna- tional Institute for Tropical Agriculture (IITA) has found Under conditions of shifting cul- this system very beneficial for maize and cowpeas4and has tivation, low management or steeply developed two types of hand- sloping or rocky soils, land is often operated planters capable of cleared by simply slashing and/or planting seed through a mulch.. burning, followed by making the seed There is nothing basically holes with a planting stick or hoe. wrong with either of. these methods. No attempt is made to actually till However, in some cases, tillage and the soil or to form a specific type seedbed shaping may some impor of seedbed. tent advantages: Slash, burn and plant: This Soils prone to drainage prob- method is most suitable for lems due to topography, soil sandy soils which are natu- conditions.or high rainfall rally loose or for other usually require the use of soils that are maintained in good tilth (a loose, crumbly raised beds or ridges for successful crop production condition) by a lengthy vege- (except for rice). tative' fallow which produces soil humus. It may be the If liming is needed to corrO t only feasible method for rocky excessive soil acidity, it soils or those with pronounced must be mixed thoroughly into /V slopes where tillage would the top 15-20 cm of soil to be/ accelerate erosion. fully effective. Slash, mulch and plant: This Chemical fertilizers contain-I method is suited to the same ing phosphorous and potassium conditions. 'The vegetation and organic fertilizers should is slashed down or killed be incorporated several centi- with a herbicide and then meters into the soil for

102 -11 4 maximum effectiveness. To control weeds (an ideal Under non - tillage methods, seedbed is completely weed- they can still be correctly free at planting time) applied using a hoe or 1% incorporate (mix into the machete, but it is definitely soil) liming materials and more work. Chemical fertil- fertilizers (chemical or izer4 containing phosphorus rganic) are best applied to the refer ence crops in a band 7.5-10 cm To shape the kind of seedbed deep that parallels the crop most suited to the particular 5-6 cm to one side. A soil, climate, and crop (i.e., fertilizer furrow can be made raised beds, ridges, flat easily with a wooden plow or seedbeds). other animal-drawn implement. Primary tillage refers to the ini- Most animal- or tractor-drawn tial breaking up of the soil by planters require a tilled seedbed for successful opera- plowing or using a heavy-duty digging tion. There are exceptions, hoe. Depth of plowing usually ranges however, such as the IITA planters. from about 15-30 cm, depending on the type of plow used, its traction source, and the soil. For example, Methods Involving Tillage an ox-drawn wooden plow will not have the penetration'ability of a tractor- drawn moldboard plow, especially 'in Tillage refers to the use of heavy soils. animal- or tractor-drawn equipment Secondary tillage refers to any addi- or hand tools to work the soil in tional tillage operations between preparation for planting and has plowing and planting to break up five main purposes: clods, cut up trash, kill weeds, and To break up and loosen the smooth out the seedbed. It is most soil to favor seed germina- commonly performed with some type of tion, seedling emergence, and root growth harrow (an implement used to pulver- To chop up and/or bury the ize and smooth the soil). Secondary previous crbp's residues so tillage is shallower than-planting they will not interfere with the new crop and requires less power. Ridging

103 1.115 and bedding (forming ridges or beds ing (cultivating). for raised planting) also can be Plow/Harrow/Plant: This is the most common system where ani- included in this category. mal- or tractor-drawn planters Reference Crop Tillage Systems are used, unless the soil breaks up well enough under The reference crops share the plowing alone. If soil condi- same basic tillage methods, but tions are conducive to weed growth, the ground should be these vary with the particular soil, harrowed as'close to planting the available tillage equipment, as possible to give the crop a head start on the weeds. and the need for incorporating lime Minimum Tillage: Farmers with or fertilizer. There are three basic access to tractor- or animal- tillage systems, each with advantages drawn tillage equipment may overdo tillage, especially and disadvantages: through repeated harrowings a Plow (or hoe)/Plant: If plowed to control sprouting weeds or at the right moisture level, break up clods. one some soils (especially loams crop of weeds by sLirring the and sands) may be suitable for soil only stimulates another sowing with a planter without by moving other weed seeds any secondary tillage to closer to the soil'surface. break up the clods. Most Excessive tillage stimulates soils can be hand-planted the microbial breakdown of after plowifig, since the humus and may further destroy g farmer has better control good soil physical condition over seed depth than when a by over-pulverizing the soil. mechanical planter is used. The machinery, animal, and He can also push -any big foot traffic also compact the clods aside or break them soil, impairing root growth up while walking 4..xin the row. and drainage. This type of roug.. seedbed is Tillage is seldom excessive:04. actually very advantageous in when hand tools are used to terms of weed control since prepare ground for the refer- * the'cloddy surface discourages ence crops, because of the their growth. It also favors amount of labor it would moisture penetration and involve. Slash-and-burn and reduces runoff. On the other slash - and -mulch methods fall hand, if bedding or ridging" under zero tillage, as do is needed, a better job can methods using specially - be done if any large clods adapted mechanical planters to are first broken up by harrow- sow seed into unplowed ground O

104 (common in the U.S.). dThe ful, but this is offset by plow/plant system described 'the fact that they are mono- above or plowing and planting cots. Small seeds require in one tractor pass are shallower_ planting than larger examples of minimum tillage. ones, and cloddy soils do not The savings on equipment wear allow this type of precision and fuel are advantages where if mechanical planters are tractors are used. used. Tillalp and Seedbed Fineness 3. Farmers can usually get by The degree to which clods with cloddier seedbeds when hand planting. They have more need to be broken up depends mainly control over planting depth .on seed type and seed size and and can push any large clods aside. In addition, it is whether hand planting or mechanical very common under hand plant- planting will be used. ing to sow several seeds per hole, which gives them a better" 1. Seed type: Maize, millet and chance of breating through. sorghum are monocots with Clayey soils, especially those seedlings that break through the soil with a spike -11.Mb low in humus, are usually in a clod- tip. This reduces the need dier condition after plowing than fora clod-free seedbed: Pea- nuts and other pulses are loamy or sandy ones. Most plowing dicots, and emerge in a takes place at the end of the dry blunt form, dragging the two

seed leaves with them; they season, when soils are very dry, - tend to have more trouble which accentuates the problem. Rain- with clods. fall following plowing may signifi-

2. Seed size: Large seeds have ' more strength than small seeds cantly reduce clod problems on some enabling young shoots to push soils by breaking up the clods. more effectively through rough seedbeds. Maize seeds 'Tillage Depth are large monocots. which A plowing depth in the 15-20 cm gives them especially goof: ".4,11od handling ability. Pea- range is usually adequate, and there uts and the other pulses are is seldom any advantage in going 1 ge-seeded, but this advantage is partly offset, since deeper. In fact, shallower plowing they a dicots. The small is often recommended for low rainfall seeds of 'sorghum and especially millet are less power- . areas like the Sahel to conserve N.

105 117 a moisture. preparing land: burning, burying and In some areas, tractor-drawn mulching: sub-soilers (long narrow shanks that 1. Burning - -This destroys the organic matter contained in penetrate down to 60 cm)are used in the residues, but may be the an .attempt to break up deep hardpans only feasible solution where (compacted layers). Results are suitable equipment is lacking or where time is short. fair to poor, depending on the type 2. Burying -- Chopping residues up of hardpan; those consisting of a with a disk harrow or slash:ilk' dense clay layer often re-cement and then plowing them under is a common practice in mechan- themselves within a short time. ized farming. About 65-80 percent of the 3. Mulching--Chopping up residues reference crops' roots are found in and leaving them on top of the ground has some definite bene- the topsoil, since this layer is more fits such as greatly reducing fertile (partly due to its higher soil erosion caused by rainfall and wind as well as water organic matter content) and less com- losses due to evaporation. pacted than the subsoil. However, However, there are two disadvantages to mulching which any roots that enter the subsoil can should be considered: utilize its valuable moisture Residues are left an the reserves, making apritical differ- surface and can interfere withthe operation of equip- ence during a drought. Proper fer- ment such as planters, plows, tilfxation of the topsoil will and cultivators which may plug up. encourage much deeper root develop- Mulching is not recommended ment.-On the other hand, poor drain- for peanuts, especially in age and excessive acidity in,the sub- wet regions, since they are very susceptible to Southern soil will hirider or prevent root stem rot' (Sclerotium rolfsii), penetration. which can incubate on unbur- ied residues from anytype HandlinvCrop Residues of plant (see page 243). There are three basic ways of handling the p'revious crop's residues (stalks, leaves, branches) when

106 O

Animal versus Tractor Power: Some 5-20 ha of land. In this case, Considerations for the Small Farmer small horsepower equipment may be very suitable. The Inter- In the developing countries, national Institute for Tropi- ' tractcppower and its associated cal Agriculture (IITA) farming -,,systems program has developed equipment are mainly confined to a 5 hp gasoline-powered multi- purpose equipment unit that large farms and to areas where can plant field crops with a labor costs are high. The large two-row,"punch",planter, haul investment, fuel and repair costs, 500 kg in a trailer, and convert to a walk-behind tractor and.maintenance requirements' all for rotary tillage, ridging, brush slashing, and plowing weigh heavily against the purchase rice paddies. Other types of of such machinery by small farmers. low-horsepower units are available from other manufac- Spare parts and the necessary repair turers. facilities are edmmonly lacking, The small farmer can some- meaning that a breakdown can be dis- times benefit by hiring tractor work on an as-needed astrous. A study by ICRISAT on the basis during, peak periods economics of full-size tractors'in when his normal labor supply is insufficient to meet India showed new evidence that they demands. significantly increase yields, cropping intensity, timeliness or gross Basic Tillage Money can Equipment for returns per hectare. ,Plowin& and usually be much better spent on Harrowing mai traction equipment, improved seeds, fertilizers, and other high- Hand Impleients: Heavy duty return inputs. digging hoes can be very effective However, there are two situa- for small areas. In Kenya, for tions where tractor power can be example, nearly all small holdings justified: are prepared this way, although an Animal-drawn equipment may average family cannot handle much not be sufficient to meet the more than 0.5 ha with this method. production needs of the intermediate farmer who has about In a wet-dry climate, most land

107 11.9 0

A digging hoe and a One common type of wooden plow. heavy duty hoe.blade. Most of them have metal tips to reduce wear.

preparation takes place when the through the soil. Their effective- soil is hard and dry, which poses ness depends a lot on soil type and added obstaces for hand tools. moisture content. The grooves they Some extension services recommend make also can serve as seed and fer- that land be prepared at thp end of tilizer furrows. the previous wet season before the Moldboard plow: This is the soil dries out. However, this is ideal plo'W for turning under grass, not always possible due to standing green manure crops, and heavy crop crops. residues such as chopped-up maize Wooden Plow: Designs of stalks. It also buries weed seeds wooden plows go back many centuries. deeper and damages` perennial weeds They often are animal drawn, and more than other equipment. Mold- . some haVe a metal tip. They do not board.plows are available in animal-- invert the soil or bury crop resi- drawn-models (usually just one plow dues but basically make grooves bottom) and tractor models (usually-

108 120 Disk Plow: Better suited than the moldboard to hard, clayey, rocky or sticky ground, but does not bury residues as effectively. This is an advantage in drier areas where surface residues reduce wind arid water erosion and cut down moistureevapor- ation. Disk plows are not recommended for peanut ground where South- ern-stem rot is a problem, because. 0 A moldboard plow. The surface plant residues hargor the moldboard section is spores. They also will not do an curved so that it turns over the soil slice that .effective job turning under grass is cut by the plowshare. sod. Disk plows are mainly ayail- able,in tractor -drawn models. 'Unlike I two to six bottoms). Depending on moldboard plows,' they are less likely plow size (width of the.moldboard as to form a plow pan if used at the viewed from the front or back) and same depth year after year. soil condition, they will, penetrate Ridgin4,_Plows (Lister Plows to 15-22sioni. or "middlebreakers"). These basically con- . Unless equipped with a spring sist of a double-sided moldboard trip device, moldboards do not that throws soil both ways .\ This handle rocky soils well. They are will produce a series of alternating not as well suited to drier areas as furrows (trenches) and ridgis when" disk plows. They also encounter operated over a field. Depending on problems in sticky clay soils and the climate and soil, the crop is may form a plow pan (a thin com- either planted "in the furrows (in pacted layer that can hinder root low rainfall areas with no drainage growth) If used at the same depth problems)" or °yap of the ridges year after year. (in high rainfall areas orthose

109 121 S

,models. They throroughly pulverize the soil and partially bury crop residues. Heavy duty model; cln be used for a once-over complete 411- age job. The disadvantages are tha,power requirements are very high and the soil can be easily overworked with this implement.

'In fact, rototilltrsdo a 'far more thorough lob of.seedbed preparation than is needed for he refer- A ridging plow or ence-crops and.are hest used for

middlebr.eaker for making , . raised beds or ridges vegetable ground.

'with drainage problems). Such furrow planting is advantageous in o drier areas fo cereal crops, since it conserves moisture.\k.. Soil is thrown into the row as the season'. progresses for weed control,.and ---, this also sets the roots deep into the soil, where moisture is'more adequate. Stich furrow planting is not recommended for peanuts and often not for beans dole to increased

root rot and stem rot problems. A rototiller or rotavator. Rctotillers (rotovators): Note -the revolving blades under the hood behind the These are available in tractor-powered wheels.

110 122 4

Disk Harrows: Disk harrows failure unless regularly greased. are.commonly used after plowing to Large, heavy duty versions pulled break 4 clods, control weeds, and by tractors are often called Rome smooth the soil before planting. plows and can sometimes substitute They are also used to chop u6 for plowing. The gangs of disks Coarse crop residues before plowing are offset to the direction of (especially if a moldboard or disk travel so that they cut, throw, and plow will be used), but heavier loosen the top 7.5-15 cm of soil but models with scallpped disks (disks pack down the soil immediately with large serrations). are most below that. Repeatedly harrowing effective for this purpose. Both a field prior to planting can animal and tractor-drawn models actually leave it harder than are available but they are expen- beforaplowing.if done when the sive and prone t9 frequent bearin "' soil is moist.

Spike-Tooth Harrows: These consist of a metal or wood frame studded with pegs or spiket; extra weight in the 0 form of stones or logs may be needed under some conditions for maximum effectiveness. They are used to smooth the seedbed and break up clods (at the right moisture content); and are especially suited for killing small weed seedlings that may emerge before planting.

Spike: tooth harrows are made in many. widths and are classified by weight andthe length of the Animal-drawn disk harrow tines. In some capes, this type of

123 Two models of a spike-tooth harrow A-spring tine harrow

harrow can be run over the actual hard or trashy ground but handle % crop rows from several days after stones well. planting up until the seedlings are Field Cultivators: These are a few centimeters till to control similar in appearance to chisel plows, early geminating weeds or to break but usually are not as built as heavy. up any soil crusting. Spike-tooth They can be used for initial tillage harrows will clog up if trash is on ground with little surface resi- left on the soil surface. due, but are mainly used as a secon- Spring Tooth Harrows: These dary tillage implement for weed con- have tines made from spring steel that trol; Most models are designed for dig, lift, and loosen the top tractor use. 7.5-10.0 cm of soil, break up clods, (Additional information on the and smooth out the seedbed. Both use of animal-drawn equipment can be ti animal and tractor-drawn models are found in Animal Traction, U.S. Peace available. They are not suited to Corps Appropriate Technologies for

112 124 Development Manual Series #12, by Peter Watson, 1981.)

Seedbed Shape

The best seedbed shape depends more on the climate and soil involved than on the particular reference crop. Flat Seedbeds: This shape is used where soil moisture is adequate for crop growth and where there are no drainage problems. Under such conditions, the Beans grown on raised beds reference crops are often planted on a flat seedbed and then "billed up" with soil (soil is moved into the ref., and helps control water erosion crop tow and mounded around the if the ridges are run on the contour. plants) as the season progresses to Water infiltration is encouraged and ruts- control in-row weeds, provide sup- off minimized. In addition, ridge plant- port, and improve drainage. In warm, ing makes for easier entry of digging humid areas where stem rot is a prob- equipment when peanuts are harvested. lem, this practice is not.recommended Finally, more topsoil is provided for for peanuts. crop growth under this system. The Raised Seedbeds (Ridge or Bed main disadvantage of ridge planting Planting): Under heavy rainfall and/ is the accelerated loss of soil mois- Or poor drainage, the reference crops ture from the mounds--normally not a are usually planted on ridges or serious problem in wet areas except raised beds to keep them from getting during dry spells. In drier areas "wet feet". This also helps minimize mulching would be beneficial. In en. soil-borne disease problems like root regions where the wet season starts

113 125 for peanuts in moist areas, since it encourages stem and root rots, particularly if soil is thrown into the row. Note: Local farmers usually , have good seedbed experience, so beware of tampering-with-time tested--- methods without first considering all the angles and running some trials. Equipment for Seedbed Shaping Flat seedbeds usually require

Land leveling with a board no special efforts beyond plowing and possibly harrowing. If additional land levelin& is required, out slowo the crops may be flat- the small farmer without access to planted ind then later "hilled up" special tractor-drawn leveling equip: as the riins increase. Furrow irriga- ment can do a satisfactory job drag- tion always requires ridge planting. ging a heavy, board hitched to two Furrow Planting: Under condi- draft animals over the field.

tions of Low rainfall or poor soil Ridges or beds can be made water-holding capacity (i.e., sandy with digging hoes, special ridging soils), crops are often planted in plows (see tillage equipment section) the furrow bottom between ridges or tractor-drawn disk-bedders (roll- where soil moisture is greater. Soil ing disks arranged at opposing angles can then tle thrown into the furrows to throw soil up to form beds). The to control in-row weeds and improve crop can be planted either on top of drainage (if rainfall picks up) as the ridges or in the furrows, depend- 4. crop growth progresses. This type ing on the soil and climate. of sunken planting is not recommended

114 typical mechnical planters Summary of are used. Land Preparation To-cut down on soil compaction and other effects of over- Recommendations for working the soil as well as to reduce labor, machineu_ The Referencetrops- ---and-firelThosts, it is best to use the minimum amount of tillage consistent with ade., quate seedbed preparation. 2. Tillage Depth

Land preparation is a very There is seldom any advantage to plowing deeper than 15-20 cm. location-specific practice varying Shallower plowing may be advis- with climate, soil type, crop, man- able in drier areas to reduce agement level, and available equip- wind erosion and moisture losses. ment.' The following is a summary of 3. Crop Residue Management the principal factors involved in Leaving crop residues on. the choosing the most feasible and appro- soil surface is especially priate land preparation method and advantageous in drier areas since it reduces moisture seedbed shape for the reference losses and wind erosion. It. crops: also reduces erosion due to rainfall and increases water 1. Seedbed Fineness (thorough- retention. ness of preparation) When growing peanuts (and Maize's large seeds and spike- sometimes beans), complete like emergence gives it the residue burial is usually best clod-handling ability of recommended where Southern the reference crops. stem rot (Stlerotium) is a Rough cloddy) seedbeds dis- problem, since the disease courage weed growth,and :an incubate on surface plant reduce erosion caused by rain residues. or wind; they also increase With the other reference .water retentionby cutting crops, surface residues may down water runoff. sometimes aggravate certain The reference crops an toler- insect and disease problems. ate a rougher seedbed when planted by hand than when

115 127 4. Suitability of Equipment The moldboard.plow is the Seed Selection most effective implement for burying crop residues and

A disk plow is better suited than the moldboard to hard, clayey, rocky or sticky ground but does not bury residues or Factors Affecting grass sod effectively. Variety Selectiwt Chisel ploys are best suited to lowerriainfall areas and leave trash on top of the soil. They are fairly inef- The selection of a locally- fective on wet soils. adapted variety with good yield Disk harrows handle clods better than spike- (peg) potential and acceptable grain tooth and spring-tooth harrows characteristics is fundamental to but are more costly and prone to repair problems. successful crop production.There 5. Seedbed Shape are several important variety- Ridge planting is recommended related characteristics that should for all,the reference crops be considered when selecting seeds: under high rainfall or poor drainage. 1. Yield potential: This is related Flat planting is best suited to inherent natural vigor and to soils with good drainage. other characteristics listed However, soil can be mounded below. into the crop row as growth 2. Time to maturity: Varieties

. progresses to control weeds fall into three general matur- and improve drainage if rain- ity classes: early-, medium-

. fall increases. and late-maturing (when grown, Furrow planting is best suited under similar temperatures). to low rainfall areas since it Early varieties produce a conserves moisture. crop more quickly, but yields may be about 10-15 percent Peanuts and beans are espe- lower compared with slower- cially susceptible to root maturing types if both receive rots favored by excess mois- adequate moisture. However, ture. They should be either early varieties are especi- flat-planted or ridge-planted. ally well suited to short

116 128 rainy seasons or sequential cropping. 6. Resistance (partial tolerance) ______to-insectsT-disoases;-and-7---- Since-Cif-Cifis a nematodes, as well as to bird strong influence on a var- damage and soil problems such iety's actual length of. grow- as excessive acidity and low ing period, some countries phosphorus levels. Reference like the U.S. are now labeling crop varieties can differ con- maize varieties in terms of siderably in their tolerance the growing degree days (total to these problems, whicn are heat units) required for matur- some of the major concerns of ity rather than calendai days. plant breeding work. 3. Elevation adaption: This has Resistance to lodging also is to do with a variety's time an important consideration in to maturity and growth abil- selecting a maize variety. ity aedifferent elevations and temperatures. In regions with pronounced variations 7. Growth habit and other plant in elevation such as Central characteristics: For example, America, the Andean countries, bean varieties can bo bush, semi-vining or rining in their and Ethiopia, maize and sorghum varieties are classified growth habit.; millet varies according to their elevation in tillering ability and sor- adaption (i.e., 0-1000, 1000- ghum in its ratooning poten- 1500, etc.); 'a similar system tial (see page 555. may also be used for beans and Plant height and the ratio of other pulses. leaf and stalk also varies 4. Heat or cold tolerance: Var- with variety. leties vary in'their toler- 8..Daylength sensitivity (photo- ance to excessive heat or sensitivity) varies markedly cold. among sorghum and millet var- 5. Drought tolerance: Even varie- ieties (see page 45). ties within a crop can vary 9. Seed color, stor- considerably in this respect. ability, etc. In a 1978 International Maize' and Wheat Improvement Center (C1MMYT) maize trial, a variety selected for drought tolerance outyielded the best full-irrigation variety by 64 percent under conditions of severe moisture shortage.

117 129 two or more inbred-lines Of i---- crop. This is relatively Traditional easy to do with maize and sor- Versus Improved ghum, and a number of hybrids Varieties are available to these two crops. Hybrid development in peanuts, beans and the other In selecting a variety, it is pulses has proven more diffi- important to understand the differ- cult, and they are not yet generally available. Millet ences between traditional varieties, research is still at too early hybrids; synthetics, and other a stage for hybrids to assume much importance. improved varieties. When grown under similar con- 1. Traditional (local) varieties: ditions, an adapted hybrid may out- They tend to be relatively low-yielding but are usually yield the best adapted, normally-pro- hardy and have fair to good duced varieties by 15-35 percent, resistance to local insect and disease problems. However, but not always; Despite these pos- most are adpated to low levels sible yield benefits hybrids have of soil fertility and management and often do not respond several disadvantages: as well as improved types to Unlike naturally produced vari- fertilizer and other improved eties, the seed harvested from practices. Native varieties of maize, sorghum and millet a hybrid should not be 'replanted by the farmer. If tend to have an overly high reseeded, a hybrid begins to ratio of stalk and leaves to grain, but this may be an degenerate and revert back to the original (and usually less advantage where livestock are important. desirable) lines from which it was developed. Yields may Despite certain disadvantages, drop-as much as 15-25 percent local varieties maY be the each' successive crop. Many best choice in some situations small farmers lack the incli- During the first years of the nation or the money to buy Puebla maize project in Mexico new seed for each planting (see page 80),. some of the unless special arrangements local varieties consistently and educational efforts are outyielded anything the plant made. breeders could come up with. Hybrid seed may be several 2. A hybrid is a type of improved times more expensive than that variety produced by crossing of other types.

118

130 Hybrids require good manage- tal improvement and consists ment or they may not yield of natural crossing between much more than other types. lines with no attempt made to test for combining ability Hybrids show a narrower range (as with synthetics) and con- of adaptation to differentgrow- tinually selecting seed from ing conditions than other vari- plants showing the best com- eties; this makes finding a binationvf desirable char- suitable hybrid more difficult. acteristics. While yields It is estimated. that 131 dif- may not be as goodlas those ferent hybrids had to be from hybrids or synthetics, developed to suit varying the seed is cheaper and also maize growing conditions in can be replanted. the U.S. 3. Synthetics are improved varieties that have been developed Guidelines for from cross-pollinating lines Selecting (naturally pollinated with no Quality Seed purposeful inbreeding as in hybrids). These lines are first tested for their combin- Seed quality can be influenced ing ability and:then crossed in all combinations. Synthe- by..the following factors: tic varieties often yield as 1. Varietal purity: Farmers who well as hybrids under small use their own harvested seed farther conditions and have for replanting can be reason- several advantages over them: ably assured of varietal pur- They have greater genetic vari- ity, especially with crops ability than hybrids, which that are naturally self-pol- makes them more adaptable to linated (millet, sorghum, pea- different growing conditions. nutes, cowpeas, beans, and most other pulses). Since The seed costs less than that maize is cross-pollinated, of hybrids. there is opportunity for "contamination" from other nearby Unlike hybrids, seed har- maize varieties. This can be vested from a synthetic can minimized by selecting seed be replanted without loss of for replanting from the inner vigor as long as farmers are part of the field. willing to select it from the plants with the best charac- Commercially available seed teristics. may or may not have good varietal purity, depending on its 4. Varieties improved through source and the country's com- mass selection: This is the mercial seed standards. In most elemental form of varie-

119 131 some areas, certified seed is crops with small seeds like available with guaranteed millet and sorghum, where genetic purity and tested separation is more difficult. germination. 5. Seed-borne diseases: Some dis- 2. Germination and vigor depend eases like anthracnose may largely on the seed's age show visible symptoms on con- and the conditions under taminated seed, while many which it has been stored. others do not. Certified seed, High temperature and humidity if grown under the proper pro- as well as insect damage (wee- cedures of inspection and vils, etc.) can drastically roguing (elimination of dis- reduce both germination and eased plants), is free from vigor. Certified seed is certain seed-borne diseases usually labeled with a tested and is especially recommended germination percentage, but for beans when available. post tested storage conditions Some common fungal diseases can make this a worthless are carried mainly on the -'seed guarantee. You should encour- coat surface and*can be con- age farmers to run their own trolled by dusting the seed, germination test (see page 121) with a fungicide; others (espe- before planting any seed, cially viruses) are internal regardless of source. and have no control (see page 3. Visual traits: Mold, 250). insect damage, cracking, and shrunken or shriveled seed How to Select mean trouble. Home Grown Seed IMPORTANT NOTE: Beans, soybeans and shelled peanuts are very susceptible to damage Most farmers not using hybrid from rough handling of dry will set aside some of their har- seeds in harvesting, processing, and shipping. Dropping vested seed for replanting future a sack of beans on a cement .floor is enough to harm them: crops. This is fine as long as the Both the seedcoats and seeds variety is suitable, storage methods crack very easily; careless handling can also cause invis- are adequate, and seed-borne dis- ible damage. In both cases, eases are not a problem. If the these injuries can lead to stunted, malformed seedlings guidelines below are followed, the lacking in vigor. farmers actually may be able to 4. Impurities such as weed seeds; improve the varieties they are using These are more of a problem in

120 or at least prevent a decline in 4. Additional guidelines for their performance: maize: When choosing among good ears after harvest, phy- 1. Seed selection should start sical differences like the while the cropis still grow- number of kernel rows, kernel ing_ in the field: Most farm- size, and filling of the tips ers wait until after harvest and butts of the cob are rela- to select seed for replanting tively useless as indicators And go largely by seed or ear' of yield potential. However, 'size. Selecting maize seed the very small, misshapen from the largest ears may have seeds-at the extreme ends of little, if any, value. This the cob should be discarded. is because the ear's size may Check. also for uniformity.of be due less to the plant's kernel color and for insect inherent genetic ability than .damage. to environmental or management factors like fertility, plant How to Conducta density, and available mois- Germination Test ture. 2. When selecting plants as potential seed sources, keep Farmers should be encouraged in mind the important plant to run a germination test on seed characteristics that favor good yields: before planting,_xegardle -- r-rra esistance to disease, source. The same holds true for . insects, drought and nematodes; extension workers receiving ship- general plant vigor, ratio of stalk and leaves to grain, and ments of improved seed.Germination time to maturity. figures that appear on seed labels Maize: Resistance to lodging, can be inaccurate even if the tests extent and tightness of husk covering (for insect, bird,,and were conducted fairly recently. water resistance), and number Warm, humid conditions in the'tropics of well-formed ears per plarit. can rapidly lower the germination When selecting maize plants, make selections from well rate. To run the test: within the field to avoid pos- Count out 100 seeds and plaie- sible cross-pollination, so them on top of several thick- this is not a problem with nesses of moist newspaper. them. Spread them out enough so you 3.Mark the selected plants with can distinguish which ones cloth or stakes. have germinated.

121 133 .1

Carefully roll up the moist newspaper so that the seeds Planting remain separated from each other and stay pressed against the newspaper. Place in a plastic bag or periodi- ally re-moisten the newspaper to keep it ftom drying out. s Sprouting time will vary with temperature, but you should be The Goals of able to get a good idea of Successful Planting germination within three to five days unless it is unusually,cold. Good seed should have a germination rate of at When planting, farmers must least 80-85 percent under =do:split:1h four objectives in order these conditions. Up to a point, you can compensate for to promote good crop yields: low germination by planting 1. Attain an adequate stand (pop- more seed, but below a rate ulation) of plants. This of 50 percent or so seedling requires seed with good,germi- vigor may suffer also. nation ability, adequate land It is a good idea where pos- preparation, sufficient soil moisture, correct planter cali- sible to supplement this type of bration (adjustment) if mecha- test with an actual field test, nical, planters are used, proper planting dept and control of since soil conditions are not usually soil insects a d diseases as ideal. Plant 50-100 seeds, keep that attack seeds and young seedlings. In some areas, the soil moist enough, and then birds and rodents also cause problems. count the emerged plants. If ggrmination is very much lower than 2. Attain the desired plant spec- ing. both in the row and with the' newspaper method, do some between the rows. troubleshooting to see if insects or 3. Observe timeliness in land seeds may have caused problems. preparation and planting.. The right time to plant

depends on the crop's charac- , teristics (i.e., peanuts should be planted so that harvesting will 'be likely to

122

134 occur during reasonably dry each hole and space the holea weather), the onset of the rather far apart, partly to rains and overall rainfall pat- save labor. This,practice tern, the influence, if any, can often reduce yields by of planting date on insect and resulting in too low an over- disease problems such as aor- all seediai rue and too much ghum head mold: competition among the plants, -4. Use the right. type of seedbed that from the same for the particular crop, soil, and climate (see page ). 2. Improvements in Hand 'Planting Hand-operated, mechanical "punch" 'Or "jab" planters are Planting Methods available that make the plant- And Equipment ing holes and drop in the seed in one movement (the seed - is automatically metered out from a reservoir). They are operated like an ordinary 1. Hand planting with a planting planting stick (jabbed or stick, hoe or machete:This punched into the ground) but is the most common method used are much quicker and are also by small farmers tOthe devel- very usetul for filling in ary oping world. "skips" (vacancies) in larger fields. A hectare of maize Advantages can be planted in 15-20 person- Equipment costs are negligible. hours. The farming systems program of IITA in Niger Less thorough seedbed prepara- has designed a.very succ ss- tion is needed than for most ful punch planter suite mechanical planters. The for planting maize, sorghum, farmer who hand plants can cowpeas, beads, and soybeans push large clods out of the into untilled ground: It is way while walking down the also capable of planting row or can plantdirectly into through'a dried-mulch. The untilled soil. IITA punch planter can be Disadvantages built ima-workshop with access to metal shears (no Time and labor requirements welding is needed). (Write are high: it takes three or IITA for:plans.) Other types four person-days to plant a of punch planters are avail- hectare by hand. able commerciatly in some When hand planting, farmers countries. usually put several seeds

123 135 Iz S

Hand-pushed planters: Most !!!ElTaltx parallel crop rows models require a fairly loose are required if weeding is to clod-free seedbed for.satis- be done.with an animal- or factory operation.Howevtr, tractor-drawn cultivator. IITA's farming systems pro- Farmers can easily construct- gram has designed a very effec- a parallel row "tracer" con- tive rolling punch planter sisting of a wood or'bamboo (called aarotary injection frame with hardwood or steel planter, wee illustration) teeth for marking out rows. that can be built in any work- (A design for this bandy imple- shop with welding and metal- ment,can be found in the Peace shearidg capabilities and is COrps' Animal Traction manual.) being manufactured by Geest Improved seed-spacing accuracy OversiasMechanization Ltd., can be achieved by running a West Marsh Road, Spalding, rope, or chain down the row ' .Lincolnshire PE11-2BD, England with knots or paint marks to (price is about $225 U.S.). indicate the proper spacing. The rotary injection planter' Otherwise, farmers commonly uses the same principles as make large errors in spacing the hand punch planter, but wheil using planting sticks or has six punch-injection dribbling out seeds into a devices on a rolling wheel plowed furrow. plus a following press wheel to firm down the seed row. 3. Animal- and tractor-drawn mech- The standard design produces anical planters are available

a seed spacing of 25 cm, but in many different models. A . alternate rollers can be made farmer using a one-row animal-

*Mt for different. spacings. The ' drawn planter can sowvabout rotary injection planter is 1-1.5 ha inn day and about also available as a four-row, 5-8 ha using a,two-row tractor- hand-pulled'iodel for planting drawn planter. direct-seeded rice. Here are' some. important con- Hand planting into furrows siderations concerning these made with an animal- or types of planters: tractor -drawn implement: A Most mechanical planters wooden plow, cultivator shank require a more thoroughly pre- or other implement can be used pared seedbed than iiineeded to make seed furrows in for hand planting. Some mod- plowed ground. If certain , als have special soil openers precaUtions are followed, the that permit satisfactory., fertilizer can be placed in operation in hard or cloddy the same furrow (see page 157). soil.

136 41,

-tf-11.:4`0. .ta. wrt-CI. Nkty,

An animal-drawn planter with a separate hopper for banding fertilizer

The rolling "punch" planter developed by IITA and now manufactured commercially. It also can be built in a workshop.

A 4nd-pushed fertilizer band appli- The IITA designed hand-operated cator. This model places the fer- "jab" or "punch" planter, which can tilizer below the soil surface, be made in a workshop. The attached which is essential for phosphorusI metal bracket firms the soil over bearing fertilizers. The attachment the seed and spaces the next seed at the left is used to close the insertion. urrow but usually is not needed.

125 t, 137 'The farmer must be able to Plant Population and Its Effects on calibrate (adjust) the planter Croy Yields so that it drops the seeds at Up to a point, crop yields the correct intervals along will increase along with the row (see page 05). increases in plant population until the competition for sun- Some models have attachments light, water, and nutrients for applying fertiliier in a becomes too great. band beneath the soil and Excessively high populations slightly to the side of the will reduce yields, encourage seed row. This is an espe- diseases, and seriously cially effective method for increase lodging in maize, fertilizers containing phos- sorghum and millet by promot- phorous. ing spindly, weak stalks. Farmers using planters without Excessively low plant popula- fertilizer applicators will tiotts will cut yields due to often broadcast the fertilizer unused space and the limita- and plow it under before plant- tions on maximum yield per ing or leave it on top of the plant. ground; this should not be done with fertilizers contain- Under most conditions, changes ing phosphorus! Farmers buy- in plant population will not ing mechanical planters should affect yields as much as be encouraged to purchase a might be expected. This is fertilizer attachment if avail- because most crops have a good-deal of built-in buffer- able and effective. (NOTE: The applicator should not drib- ing capacity, especially if ble the fertilizer on top of the population is too low. In this case, the plants res- the ground or place it in direct contact with the seed.) pond by making yield-favoring changes such as increased tillering (millet, sorghum) and branching (peanuts, other Plant Population pulses), more pods or ears And Spacing per plant or larger ears or' grain heads. In maize, a plant density that is 40 percent below the optimum for Both plant, population and the given conditions may lower spacing affect the yields of the yields by only 20 percent.

reference crops, and extension work- Plant population changes have - a more pronounced effect ers should understand the relation- under conditions of moisture ships. stress.

126 138 What is the ideal plant population? Available nutrients: Adequate soil fertility is especially There is no easy answer to this, essential with high plant because the optimum plant density populations. In fact, fertilizer response is often depends on several factors: disappointing when plant pop- Type of crop and variety: ulations are too low for the Because of differences in given conditions. In fact, plant size and architecture, this is one of the main rea- crops and their varieties sons that small farmers often vary in their tolerance to do not get their money's increasing plant populations. worth out of fertilizer. An For example, early maturing ear of maize can only grow so maize varieties are usually big, and even high rates of shorter and smaller than later fertilizer can not make up for maturing ones and therefore too few ears produced by a may benefit from higher plant small number of plants. densities. Beans and cowpeas Management ability: High pop- respond well to populations ulations require more soil three to four times higher fertility and moisture as than for maize due to their well as better overall general smaller plant size and a management. growth habit that favors better light interception. Plant Spacing and Its Effects on Crop Yields Available soil moisture: The optimum plant population den- The reference crops are row sity varies directly with crops for some very good reasons. A rainfall and the possibility of moisture stress. Plant row arrangement permits quicker and population has a stronger easier weeding. and facilitates most effect on yields under low moisture conditions than Other growing operations. Row crop- when moisture is adequate. This is because increased ping with its handy space for equip- populations also increase ment, animal, and human traffic water use, although plant spacing can make a difference. allows for ease of mechanization and This is particularly true for handling, no matter what the level of maize and sorghum, because

yields can be significantly sophistication. Distributing a given . reduced by relatively small plant population over a field involves increases in plant population when grown under moisture both plant spacing within the row and stress.

127 133 the distance between the rows (row animal-drawn equipment requires more width). space between rows (wider row widths) Plant spacing within the row: than when only hoes and backpack The number of seeds that need to be sprayers are used. Beans can be planted per meter or foot of row spaced in narrower rows than maize or length depends entirely on the plant other tall crops and still be weeded population and row widths that have with an animal -drawn cultivator with- been chosen according to recommenda-. out knocking the plants down. Row tions. The main concern then becomes ,width influences crop yields in four whether hill planting or drill plant- ways: kig should be used. In drill planting As row width is narrowed, the mechanical planters drop seeds out Plants can be spaced farther apart within the row and still one at a time along the row. Small maintain the same population. farmAms who hand plant their crops Up to a point, this makes for better weed control due to usually use hill planting, sowing earlier and more effective several seeds per hole and spacing between-row shading by the crop. the holes rather far apart. This Narrower rows allow for higher ; reduces time and labor and also may plant populations without over- improve seedling emergence under crowd ins. crusty soil conditions, but it may Asow width is widened, plants have\to be crowded closer lower yields somewhat because of inef- together within the row in ficent use of space and increased com- order to maintain the same population. This may lower petition between the plants within a yields. \1 hill for sunl.ight, water, and nutri- Should the use 4,f narrower rows be encouraged?Here are some things OD ents. consider: Row Width: Space between rows 1. Switching from 100cm to 75 cm is determined by the type of equip- rows in maize and sorghum may increase yields by as much as ment used as well as by plantsize or 5-10 percent when total plant "spread". The use of tractor- or population is kept constant. When grown alone, bush beans and bush cowpeas are ususally If tractor -drawntequipment is planted in narrow rows (45-60 cm) used, overly narrow rows may by most small farmers. Under increase plant damage from good management and yields, tractor tires and passing most studies have not shown equipment as well as increase much advantage to reducing soil compaction near the row peanut row width below 75-100 cm. zone. If several crops are Given the marginal moisture being grown under tractor conditions under which millet cultivation, it is more con- is grown, row widths less than venient to settle on a stan- 75-100 cm are unlikely to be dard row size rather than be advantageous. constantly readjusting tire spacing, tire size, and cul- 2. Row width and moisture use: tivator tine spacing. Remem- Although narrower rows cut ber, too, that row width must down water evaporation from be kept wide enough to permit the soil surface because of tractor cultivation (weeding). earlier and more complete soil This cannot be done by rely- shading, this is often negated ing solely on herbicides: by increased plant water use (transpiration) due to better leaf exposure to sunlight. Under low moisture conditions, Summary of Plant plant population has a much Population and greater influence on water use Spacing Studies than row width. Conducted with the 3. It is doubtful that a 5-10 Reference Crops percent yield increase will have much of an influence on small farmers whose yields MAIZE: Overly high populations are fairly low. Even if yields are good, switching to cause increased lodging, barren narrower rows may cause more stalks, unfilled ears, and small ears. problems than it is worth: Dry, husked ears weighing more than Narrow rows cost the farmer 270-310 g indicate that plant popula- more in terms of time, seed, and pesticide.That is tion was probably too low for the because the narrower the row conditions and that yields might have width, the greater the total amount of row length per hec- been 10-20 percent higher. Ear size tare or other land unit, since of prolific (multiple -ear} varieties there are simply more rows to deal with. will not vary as much with changes in

129 141 plant density as will single-ear vari- show that overly high populations eties;.rather the number of ears per have a negative effect on maize plant will decrease as density yields when moisture is low. increases. SORGHUM: Optimum plant popu- Hill versus drill planting: lation varies markedly with avail- Numerous trials with maize have shown able water, plant height, tillering yield increases of 0-13 percent when ability, and fertility. In vari- drill planting (one seed per hole) eties that tiller well, plant popula- was substituted for hill planting at tion is less important than with two to three seeds per hole.How- maize since the plants can compensate ever, lodging appears to be more of for overly low or high populations by a problem with drill planting. Farm- varying the production of side shoots. ers who are hand planting four to six In West Africa, the improved seeds par hole should be encouraged long-seasOn photosensitive and the to switch to two to three seeds per improved short-season non-sensitive hole and space the holes close varieties are sown at the rate of 40,- enough together to achieve the 000-- 80,000 /ha under good management; desired plant population. It is the dwarf photosensitive, long-season doubtful that switching to drill varieties are sown at rates of 100, -

planting is worth the extra labor 000 /ha or more. involved under hand planting. All the above populations are Under adequate moisture and based on monoculture. fertility, optimum plant populations PEARL MILLET: In West Africa, vary from about 40,000 to 60,000 millet is planted in hills usually a

per hectare. Plant size, management, meter or more apart; many seedsare fertility, and the varietiy's toler- sown per hill, and thinning.takes ance to plant density and available place two or three weeks later. moisture must be.considered when mak- This involves much hand labor and is ing population changes. Studiesalso seldom finished before serious com-

130 142 petition has taken place. Trials in is to keep the cereal population down Upper Volta by ICRISAT showed that to about 3000-6000 hills per hectare . millet germinatedbest when planted and the peanut density high at about at many seeds per hill and that hill 30,000 hills per hectare, or about planting-outyielded drill planting. the same as under sole cropping. However, other ICRISAT work in West In West Africa, the recommen- Africa showed no difference between dedplant population for improved yields from hill and drill plantings. varieties grown alone ranges from Population and spacing: In about 45,000-100,000/ha. Rows vary West Africa, pearl millets of the from 24-36 inches (60-40 cm) and seed Gero type are often interplanted at spacing in the, row from 15-25 cm. populations of 7500-8500 plants per For the Virginia types populations hectare with two to three other crops. of 45,000-60,000/ha have been found The taller, long-season Maiwa types to be optimum, with higher popula- are sown at 40,000-80,000 plants/ha tions recommended for the Spanish- when planted alone under good manage- Valencia types. ment. For improved dwarf Geros, popu- Early studies in the U.S. in lations over 100,000/ha are recom- the 1940's and 1950's obtained yield mended. increases of 30-40 percent by switch- Most varieties have a strong ing from row widths of 90 cm to 45- tillering ability and adjust them- 60 cm. At that time, however, average selves to varying densities through yields were relatively low(1550 kg/ha). changes in tiller production. As yields have increased over the Within limits, yields are not greatly years, the importance of row width has affected by plant population changes. diminished considerably, and most U.S. PEANUTS: In parts of West growers are using 75-95 cm widths with

Africa, peanuts are frequently inter- one seed every 10 cm, A stand of one planted in combination with sorghum, plant every 15-20 cm is felt to be millet, and maize. Because peanuts adequate, but overplanting is needed are the most valuable, the tendency to make up for any losses.

131 143 Two new developments may influ- it occurs. ence row widths: 1) smaller-size, Studies by CIAT and the Cen- dwarf varieties which will not fully ter for Tropical Agriculture, spread out to cover a 90 cm row width. Research and Training (CATIE)indi- 2) Plant growth regulators like Alar, cate that plant populations for bush which are internode shorteners (inter- beans in the range of 200,000-250,- nodes are the spaces between'nodes on 000/ha are also ideal when grown the stem and branches) which decrease together with maize. plant size and are especially suited Trials with climbing beans to runner types. show that final plant populations of

BEANS: The International Cen- 100,000-160,000/ha are optimum, ter for lropical Agriculture (CIAT) whether grown alone with trellising studies in Colombia have shown that or with maize. COWPEAS: In West Africa, bush beans grown alone give highest yields in spacings of either 30 cm improved cowpea varieties of the between rows and 9 cm between plants vining type are grown at population 45 cm between rows and 60 cm between densities ranging from 30,000-100, - plants (equivalent to about 400,000 000 /ha in rows 75-100 cm apart. CHICKPEAS: An ICRISAT study seeds/hectare). A yield plateau is usually reached around 200,000 -250,- showed that yields remained relatively stable over wide ranges of 000 actual plants per hectare; -but stand losses from planting to har- 'plant density -(4-100 plants per vest are often in the 25-40 percent square meter). range, meaning that considerable overplanting is necessary. High density plantings also appear to increase the height of the pods from the ground, which lessens rotting problems. However, very narrow rows aggrativate Sclerotium stem rot where

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144 Guidelines for seedling vigor is also likely to be Attaining a affected. Good Stand and The Desired Spacing Percent of Overplanting

No matter how well the seed . germinates, the farmer should still overplant to make up for any added Eight key factors largely plant losses due to insecta,'dis- determine whether a farmer actually eases, birds, and weeding operations. ends up with a good stand of plants When using good seed, it is usually and the right spacing for the condi- asound practice to overplant by tions: 15-20 percent in order to assure

Seed-germination ability . the recommended final stand of plants Percent of overplanting at harvest. Of the reference crops, Planting depth beans, cowpeas and peanuts are likely Seedbed condition (clods, mois- to suffer the greatest plant losses ture, etc.) and will usually benefit from even Seedbed type (flat, furrow or higher overplanting. Much depends ridge planting) on the specific growing conditions. Accurate measurement when hand planting and calibration High rates of overplanting (500 per- of mechanical planters cent or more) followed by heavy hand Soil insects and diseases thinning are a standard practice when Fertilizer placement. field planting small vegetable seeds Seed-germination ability like cabbage, tomatoes, and lettuce. Always run a germination test This is not recommended for the (see page 121 before planting; good reference crops, since their seeds seed should test out at close to 90 are larger, hardier, and more vigor- percent. Up to a point, overplanting ous in their early growth. Labor will compensate for lower germination, and seed costs are excessive with but seed testing below 50 percent high overplanting and thinning. germination should not be used since Millet is commonly thinned in West

133 145 Afrita after being overplanted Normal Ranges in Planting Depths for the Reference Crops heavily, but this should be discouraged. Maize: 3.75-8 cm 3.75-6 cm Planting Depth Sorghum: Millet: 2-4 cm Optimum planting depth varies Peanuts,_ Bears, Cowpeast with the crop, soil type (sandy ver- 3-8 cm sus clayey), and soil moisture con- Seedbed condition tent. Seeds should be plated deep Cloddiness and soil moisture enough so that moisture is available will affect, germination. Some soils, for germination, but shallow enough especially those high in silt, tend so that seedling emergence is not to form a hard surface crust when dry- impaired. Local farmers should be ing out after a rain. This can some- regarded as the ultimate authority times seriously reduce emergence, on thebest plantIng depths, but here especially for the pulses. If neces- are some general guidelines: sary, these crusts can b broken up Seeds can be planted deeper in with a spike-tooth harrow or other sandy soils than in clayey homemade device. soils without reducing plant emergence. Seeds should be in reasonably Planting depth should be firi contact with moist soil.Most deeper under low soil mois- tractor-drawn planters have steel or ture conditions. rubber "press" wheels running behind Large seeds have more emergence strength than small them to help improve seed and soil ones, but this is also affected contact. (See page 105 for more infor- by the seedling's structure. Maize, millet, and sorghum push mation on seedbed preparation.) thorugh the soil with spike- Seedbed type like tips which aid emergence. Peanuts, beans, and the other Most of the crops can be flat-, pulses emerge in a much more furrow- or ridge-planted according to blunt form. the particular soil and climate conditions. Good drainage and freedom from ponding (standing) water is

134

146 4 especially vital for peanuts, beans, Soil insects and diseases and cowpeas, which are particularly Seeds may need to be treated susceptible to root and stem rots. "'with a fungicide dust to help control They should be flat-planted where seed rots which are especially ser- drainage is good or sown on top of ious.under coot, wet conditions. ridgep or beds where drainage is Seed or soil treatment with an poor. If flat-planting, care should insecticide may also be needed to' be taken not to form a depression protect against damage from insects along the seed row where water could that attack the seeds and young seed- collect. This is a problemdhere lings. mechanical planters with heavy press Fertilizer placement wheels are used, but can be avoided Fertilizer placed too close to by using wider 'press wheels and the seeds or in contact with them may °throwing extra soil into the row prevent or seriously reduce germina- allad of the planter with cultivator tion. This depends on the kind, sweeps, amount, and placement of the fertil- Planter calibration; accuracy izer (see page 161). of hand planting

Mechanical planters must be calibrated (adjusted) prior to planting to assure that they space the seeds out correctly.

Hand planting is prone to large errors in row width and seed spacing unless some effort is made to assure accuracy. The use of a planting'rope or chain along the row with knots or paint marks to indicate the spacing ts recommended.

135 147 5. Soil Fertility and Management

Fertilizers MACRONUTRIENTS

Primary, Secon ary

NITROGEN -(N) CALCIUM (Ce) PHOSPHORUS (P) MAGNESIUM-(Mg) POTASSIUM (K) SULFUR (S) Fertilizer use is often the MIRONUTRIENTS (not primary or secondary) management factor producing the IRON (Fe) ZINC (En) largest increases in reference crop MANGANESE (Mn) BORON (B) COPPER (Cu) MOLYBDENUM (Mo) yields. However, yield response The macronutrients make up is heavily influenced by two about 99 percent of a plant's diet. factors: Nitrogen, phosphorus and potassium The control of other limiting factors: Fertilizer account for about 60 percent and are usually gives a much better definitely the "Big Three" of soil response when used as part of a "package" of improved fertility, both in terms of the practices designed to cod= quantity needed and the likelihood trol other major yield limiting factors in addition of deficiency (see Table 4). to soil fertility. This does not mean that the How fertilizer is used: secondgry macronutrients or the Good results from fertilizer cannot be expected unless micronutrients are any Less essen- the farmer knows what kind tial. True, their deficiencies are and how much to use, and how and when to apply it. not:as common, but they can have Aside from water, sunlight, just as serious an effect on crop and air, plants need 14 mineral yields. nutrients which are usually grOnped as follows:

137 148 Table 4. Amount of Nutrlents Taken Up by a 6300 kg Yield of Shelled Maize ., Grams . Macronutrients 141. Micronutrients Nitrogen 157 Iron 4200 Phosphorus (P205) 60 Manganese 1000 Potassium (R20) --.124 Zinc 30 7 Calcium . 29 Copper Magnesium 25 Boron 7 Sulfur 17 Molybdenum 0.7

Nitrogen (N) like potatoes, sweet potatoes, cassava (manioc, yuca)and tropi- Nitrogen is the most common- cal yams have lower N needs, and ly deficient nutrient for non-le- excessive amounts tend to favor gumes.klt promotes vegetative growth leafy growth over tuber growth and is an essential constituent of (with the exception of most protein and chlorophyll (needed for proved potato varieties which have photosynthesis). high N needs). Crops vary in their need for Legumes are able to satisfy N. Crops with a lot of vegetative pareor all of their N needs them- (leafy) growth have relatively high selves through the process of nitro- N needs. These include maize, sor- fixation..Peanuts, cowpeas, mung ghum, millet, rice, sugarcane, pas- beans, pigeonpeas, and chickpeas ture grasses, and most leafy and are usually able to meet their own fruit-type vegetables. Root crops N requirements in this way. Common

138

14.9 ro beans (kidney beans) are less effi- Most crop' residues like maize,'

cent at N fixation and may need up millet, and sorghum stalks supply ' to half as much N fertilizer as. lam amounts of carbon, which the maize. Too much nitrogen can adverse- microbes use for energy, but not ly affect crop growth, especially if enough N foi the microbes' protein other nutrients are deficient: needs. The microbes make up for It may delay maturity. this shortage by taking ammonium It may lower disease resis- and nitrate N from the soil. A crop tance. It may increase lodging prob- may suffer a temporary N deficiency lems in cereal crops. if planted under these conditions, Available versus Unavailable N until the microbes finish deCompos- Only nitrogen in the form of ing the residues and finally release ammonium (NH1) and nitrate (NO3) in the tied-up-N!as they die off..(Occa the soil is available.to plants. How sionally elken young legumes will be lever, about 98-99 percent of a soil's' affected.,)'trhis type of N def4iency total N is in the unavailable organ- can be prehted easily by applying ic form as part 'of humus. Soil about 25-30 kg/ha of N atplanting microbesIgradually convert this un- time when growing a non-legume!

availableti organic N into ammonium Available N is Easily Lost and theninitrate.Mostsoils are Nitrate N (NO3) is much more too low in, humus to supply N at .a readil leached (carried downward' rapid enough:rate for good yields. away from the root zone by rainfall That is why-N fertilizer is usually or irrigation) than ammoniumNI(N4), needed for non-legumes. since it is not attracted to and Available soil N can become held by the negatively chargedclay tied"np and unavailable when crop and humus particles. (These acit like residues low in N are plowed into magnets and hold onto positive y

+, and the soil. This is because the soil charged nutrients like NH4, K.

, microbes that decompose the resi- Cam and keep them from leachin10. dues need N to make body protein. 150 139 fl

The problem is that tropical and highly-weathered, red tropical soils low in pH (high sub-tropical temperatures are al- in.acidity). ways high enough to promote a Phosphorus is virtually im- rapid conversion of ammonium N to mobile in the soil: Phospho- rus does not leach except in nitrate N by soil microbes. Most vety sandy soils. Many farm- ammonium type fertilizers will be ers apply P fertilizer too shallowly and very little completely changed to leachable gets to the roots. nitrate in a week in warm soils. Young seedlings need a high The higher the rainfall and the concentration of P in their tissues to promote good root sandier the soil, the higher the growth. This means that P leaching losses of N. The best way needs to be applied at planting time. One study showed to avoid excessive leaching is to that maize seedlings take up apply only part of the fertilizer to 22 times'as much P per unit of length as do 11-week- at planting and the rest later on old plants. in the crop's growth when uptake is 44plication method is vitals higher. lv important and determines how.much of the added P gets tied u . Broadcast applica- Phosphorus (P) tions uniform applications of fertilizer over the en- Phosphorus promotes root tire field) maximize P tie- growth, flowering, fruiting and up and should seldom be recommended for small seed formation. Remember these four farmers. Placement in a vital facts about phosphorus: band, half-circle or hole near the seed is two to Phosphorus deficiencies are four times as effective as widespread: Much of a soil's broadcasting, especially native P content is tied up for low to medium rates of and unavailable. Worse yet, application. only about 5-20 percent of the fertilizer p applied will be available to the Potassium (K) crop since much of it also gets tied up as insoluble compounds. This P fixation' Potassium promotes to is especially a problem on and sugar formation, ro growth,

140 disease resistance, stalk strength, The Secondary and general plant vigor. Starch Macronutrients: Calcium (Ca), and sugar crops like sugarcane, Magnesium (Mg), bananas, potatoes, cassava, and And Sulfur (S) sweet potatoes have particularly dis high K needs. Maize, sorghum, mil-. For most crops, calcium is let, rice, and other grasses are more more important for its role as a lim- efficient K extractors than most ing material (to raise soil pH and broadleaf crops. Remember these lessen acidity) than as a nutrient. facts about K: Even very acid soils usually have Potassium deficiencies are enough calcium to meet the plants' not As common as those of N nutrient needs, while soil pH may and P: Most volcanic soils 'tend to have good available be too low for good growth. It ekes supplies. However, Only the large amounts of calcium to raise soils labcan tell for sure. Potaisium: Only about one or, the pH compared to those needed for two percent of the soil's totalplant nutrition. K Is in the available form, but this is often enough to Peanuts, however, are an ex- satisfy the needs of some ception and have unusually high cal- crops. The good news is that tie' -up of fertilizer K is cium needs which usually must be met not usually serious and never by supplying gypsuml (calcium sul- approaches that of P. fate.) This is not a liming material. Leaching losses are usually Mag4nesium deficiencies are minor: The available form of K has a positive (plus) more common than those of calcium- charge,The negatively charg- and are most likely to Occur in san- ed claYI andrbumus particles act like magnets and attract dy, acid soils (usually below pH 5.5) the plus-charged K to their or in response to large applications surfaces to help reduce leaching. However, leaching of K. Too Much calcium relative to losses can be a problem on magnesium also can bring on Mg def i- sandy soils or under very high rainfall. ciencies. Farmers who need to lime High IC applications can en- their soils are usually advised to courage magnesium deficiencies.

141 152 usedoloml1.1tic limestone (about a NAK content) generally con-

50-50 mix of Ca and Mg carbonates). . tain much more S than high analysis fertilizers such as Both calcium and magnesium are slow- 18-46-0, 0-45-0, etc. ly leached from the soil by rainfall. The Micronutrients :sulfur deficiencies are not common, but are most likely to occur under these conditions: Micronutrient deficiencies Many volcanic soils tend to are much less common than those of be low in available S. Land N,P, or K, but are most likely to near industrial areas usually receives enough S from occur under these conditions: the air. Highly leached, acid, sandy Sandy soils and high rainfall soils. Use of low sulfur fertilizers Soil pH above 7.0 (except for (see Table 17). molybdenum which is more avail- Low analysis fertilizers able at lower pH's). (those with a relatively low

Table 5 Susceptibility of the Reference Crops to Micronutrient Deficiencies

-Crop. Most Common Conditions Favoring Deficiency Micronutrient Deficiency. MAIZE Zinc Soil pH a ve 6.8; sandy soils; high P SORGHUM Iron Soil pH abov 6.13; sandy soils; high P BEANS Manganese, Zinc Soil pH above 643; sandy soils Boron Acid, sandy soils,\O above 6.8 PEANUTS Manganese, Boron Refer to above Micronutrient Toxicities: Iron, manganese and aluminum can become.overl soluble and toxic to plants in very acid soils. Boron and molybdenum'csn cause toxicities if improperly applied.

142 153 Intensively cropped soils fer- Likewise, there is no such tilized with macronutrients thing as "tomato fertilizer" or "maize fertilizer", etc. Soils differ Areas where vegetables, legumes and fruit trees are so much in natural fertility that no grown. one fertilizer could possibly be Organic (peat) soils. right for all types of soil, even for one kind of crop. When dealing with the reference crops, farmers cannot afford

Determining to waste their scarce capital on Fertilizer Needs fertilizers that might be inappro- The amount of nutrients that priate for their soils. They also different crops must absorb from need reasonable guidelines on how the soil to produce a given yield is much to apply. There are five basic fairly well known. Yet proper fer- methods used to determine fertilizer tilization is not a simple matter of needs: adding this amount for several rea- Soil testing sons: Plant tissue testing The farmer needs to know what Fertilizer trials share of the nutrients are al- Spotting visual "hunger ready in the soil in avail- signs" able form. Making an educated guess A plant's ability to recover nutrients, whether from fertilizer or natural soil sources, depends on the type Soil Testing of crop, the particular soil's capacity to tie up different nutrients, weath- Soil testing by a reliable er conditions (sunlight, rain- laboratory is the most accurate fall, temperature), leaching losses, physical soil fac- and convenient method for determin- tors like drainage and com- ing fertilizer rates. pactIon, and insect and disease problems. Most labs routinely test for

143 154 4.

available P and K and measure soil These kits give results that are pH and exchange capacity (the soil's as accurate as most farmers will negative charge). Most do not test need for growing reference crops. for available N, since results are However, if a soil testing labora-- not very accurate. tory is available farmers should be Some will be able to test for encouraged to send samples in. Ca, Mg, S, and some of the micronu- How to Take a Soil Sample trients (micronutrient and S tests Improper sampling by the vary in reliability). farmer or extension worker' is the

If the soil is overly acid, most common cause of faulty lab re- the lab will usually be able to tell sults. A 200-400 gram sample may how much lime the soil will need. represent up to 15,000 tons of soil. Most can test the salinity and alka- The soil laboratory's instructions li hazard of the soil and irrigation should be carefully read before sam- water (most common in semi-arid to pling. These are usually printed on arid areas). the sampling box or on a separate At the very least, the lab sheet. (See Appendix J for general will provide an W-P-K application instructions on how, when, and how recommendation for the crop involved often to soil test.) The better labs will tailor the recommendation of the farmer's yield Plant Tissue Tests goal and management ability, based

on the farmer's responses to a The crop can be tissue-tested questionnaire supplied by the lab. while growing in the field for N-P- Portable soil test kits are K levels in the sap. Kits cost about not as accurate as laboratory testing US $20-$42, but some of the reagents but can give a fairly good estimate need replacement every year. of soil conditions at a test site. Tissui tests are best used to The instructions state within what supplement soil test data, since the /imits 'the test kit is accurate. results can be tricky to interpret

144 1 53 by non-professionals. Sometimes the wrong part of the plant will plant sap nutrient levels are not make results invalid. well correlated to those in the soil, because weather extremes, insects, and diseases affect uptake. Defy en- Fertilizer Trials cies of .one nutrient such as N can See Chapter 8 and Appendix stunt plant size and cause P and K B. to "pile up: in the plant sap. giving falsely high read- Spotting Visual ings. The tests are also, geared to Hunger Signs" higher yield levels than most small farmers can reasonably hope to at- Severe nutrient deficiencies tain. The crops receiving low to mod- usually produce characteristic / erate fertilizer rates that provide changes in plant appearance, partic-

i the best return per dollar may show ularly in color. Spotting thesei"hun- tissue test results indicating ger signs" can be useful in determin- deficiencies. ing fertilizer needs, but there are One advantage of tissue test- several drawbacks: ing is that it may be possible to Some hunger signs are easily confused with each other or correct a deficiency while the crop with insect and disease* prob- is still growing and thus increase lems. If more than one nutrient is deficient at once, the yields. hunger signs may be too vague Total Plant Analysis: Some for accurate diagnosis. labs can run a total nutrient anal- Hidden hunger: Hunger signs will not usually appear un- ysis of plant leaves with a spectro- til the nutrient deficiency graph, but it may cost US $10-$15. is serious enough to cut yields by 30-60 percent or When collecting leaf samples, more. This "hidden hunger" it is important to pay close atten- can cause unnecessarily low yields even though the orop tion to the kit's or lab's sampling may look good throughout the instructions. Taking leaves from growing season.

145 156 soils. (Do not rely ontheir It may be too late tocorrect the recom- deficiencies by the timehun- accuracy unless mendations are based onsoil ger signs appear.Any N ap- tests and/or fieldtrial re- plied much beyondflowering time in thecereal crops sults.) will increase grainprotein The particularcrop's rela- more thanyields (such pro- tive nutrient needs(discuss- tein increases areslight ed later in thissection). compared to the amountof N used and the yieldthat is A thorough examination of sacrificed by lateapplica- the soil for depth, drainage, tion). Phosphorusshould i- texture, tilth, slope, and deally be placed 7.5-10 cm other factors that may limit deep an' this isdifficult yields or fertilizer response, including soil pH (see page to do withoutdamaging the roots afterthe crop is up 169 on liming).. and growing. Yield history and past management of the farm regard- Specific hungersigns for ing fertilizer and liMing.- the reference crops maybe found in The farmer's management ability, available capital, and Appendix G. willingness to use complementary practices like improved Making an seed, insect control, etc. Educated Guess

If no soil testresults are available for afarmer's field, a Fertilizer Types reasonable estimateof N-P-K needs And How to can be madebased on at least four criteria; Use Them or more of,the following Avai1ible soil testresults from nearby farmswith the same soil typeand a simi- Chemical (inorganic) fertili- lar liming andfertilizer zers are frequently accused history. "poisoning" the Data from fertilizertrials of everything from on the samesoil type. soil to producing less tasty and An extensionpamphlet on the nutritious food. Should the exten- crop withfertilizer recommendations for the area sion worker encourage clientfarm-

146 1&7 ers to forget about chemical fertil- Overwhelming evidence indi- izers and use only organic ones cates that chemical and organic fer- (compost, manure)? The 'organic way" tilizers work beet together. A study is basically very sound, because at the Maryland Agricultural Exper: organic matter.(in the form of hu- ment Station (U.S) showed a 20-33 mus) can add nutrients to the soil percent yield increase when chemi- and markedly improve soil physical cal fertilizers and organic matter condition (tilth, water-holding ca- were applied together, compared with pacity) and nutrient-holding abili- applying double the amount of either ty. Unfortunately, some misleading alone. and illusory claims on both sides Most small farmers will not of the issue cause a lot of have access to enough manure or oth- confusion. er organic matter to cover more than Chemical fertilizers supply a small portion .of their land ade- only nutrients and exert no bene- quately. When supplies are limited, ficial effects on soil physical they should not be spread too thinly condition.. Organic fertilizers do and are often most effective. on high- both. However, compost and manure value crops (strokes vegetables) are very low-strength fertilizers; grown intensivelyon small plots. 100kg of 10-5-10 chemical fertilizer contains about the same amount Manure at oU'IM-P-K as 2000 kg of average farm manure. The organic fertilizers need Fertilizer value: Animal manure is to be applied at very high rates an excellent source of organic mat- (about 20,000-40,000 kg/ha per year) ter, but relatively low in nutrients. to make up for their low nutrient The actual fertilizer value-depends content and to supply enough humus largely on the lypesLar_Amal, qual7 to measurably imrpove soil physical isy of the diet, kind and amount of condition. bedding_ used, and how the manerP is

147 158 stored and Inli&A. Poultry and Farm manure is low in phosphorus: sheep manure usually have a higher It tends to hsVe too little avail- nutrient value than horse, pie or able P in relation to available N cattle manure. and K. If used as the sole source Constant exposure to sunlight and of fertilizer, some. experts recom- rainfall will drastically reduce mend fortifying it with 25-30 kg of manure's fertilizer value. single superphosphate (0-20-0) per On the average, farmmanure 1060 kg of manure,. This also helps contains-about 5.0 kg N, 2.5 kg reduce the loss of N as ammonia. P205, and 5.0 kg K20 per metric ton However, it is more convenient and .(1000 kg), along with various amounts effective to apply chemical fertil- of the other nutrients. This works izer directly to the soil instead of .. out to a 0.5-0.25-0.5 fertilizer attempting to mix it with the manure. formula. (See the chemical.fertil- Manure as a source of micrOnutri izer section for an explanation of ents: When livestock such as pigs how fertilizes ratios are determin- and chickens are fed largely on ed if this is cdnfusing.) BUT only nutritionally-balanced commercial about 50 percent of the N, 20 per- feeds, their manure may be a parti- cent of the P, and 50 percent of the cularly good source of micronutri- K is readily available to plants ents if applied at a high rate. Ma- during the first month or two, nure from animals fed mainly on because most of the nutrients are local vegetation is likely to have a in the organic, form mhich first lower micronutrient content. has to be converted to the avail- How to store manure: It is best. able inorganic form by soil mi- to store it under a roof or in a crobes. This does mean,however, covered pit, but manure can be stor- that manure has good residualjer- ed in piles with steep sides to vilizer value. shed water and good depth to reduce. leaching losses by rain.

148' Widelines for applying manure; effort involved. This is a good way to use scarce a- Manure is best,applied a cou- mounts. Fresh manure may ple of weeks to a few days burn seeds or seedlings if before planting. If applied not mixed well with the soil. too far in advance, Some N may be lost by leaching. To avoid "burning" the crop seeds and seedlings, fresh Compost manure should be applied at least a couple of weeks in As with manure, large amounts advance; rotted manure is unlikely to cause damage. are needed to improve soil physical Manure containing large a- condition or supply meaningful a- mounts of straw may actually mounts of nutrients. Compost - making cause a temporary N def i- ciency unless some fertili- takes a tremendous amount of labor zer N is added. and is seldom feasible for anything Manure should be plowed, but small garden plots. (For more 'disked or hoed under soon after application. A delay information on compost, refer to the of just one darmay cause a PC/ICE Soils, Crops, and Fertilizer 25 percent loss of N as ammonia gas. Use manual.) Rates of 20,000-40,000 kg/ha are generally recommended, Other Organic but limit poultry and sheep Fertilizers manure to about 10,00G kg/ha since it is more likely to Blood meal and cottonseed cause "burning". Thii works out to about 2-4 kg/sq. m meal have much higher N contents ( 1 kg/sq. m for poultry and than manure and compost, and contain sheep manure). other nutrients as well. However, If quantities are limited, farmers are better off us- they are valued as animal feeds and ing moderate rates over a are,likely to be too expensive. larger area rather than a high rate on a small area. Bone meal (15-20 percent P0) makes 25 Manure also can be applied P available very slowly and is also in strips or slog centered expensive. over the row if farmers. are willing to make Ole extra The hulls of rice, cotton-

149 1 0 seed, and-peanuts have virtually no adequately,:'so chemical fertilizers nutrient value, hot can be used as are usually an essential ingredient mulches or to loo!;en up clayey soils for improving yields quickly. Des- on small plots. They may cause a pite their ever-increasim: cost, temporary N tie -up. they can still Frequently return good value if correctly used.

Types of Chemical Green Manure Crops Fertilizers

I See Chapter 4, page 94.

For soil application,Ars- ules are the most commonly used form. They usually contain one or more of the "Big Three" (N, P, K), varying amounts of sulfur and calcium (as carriers), and very low or Chemical Fertilizers nonexistent amounts of micronutri-

1 ents. The fertilizers can be ei- Chemical fertilizers (also ther simple mechanical mixes of two called "commercial or "inorganic" or more fertilizers or an actual fertilizers) contain a much higher chemical combination with every concentration of nutrients.than ma- granule identical in nutrient eon- inure or compost, but lack their tent. soil - Improving qualities. Few farmers will have e- nough organic fertilizer to cover more than a fractfbn of their land

ti How to Read a The Fertilizer Ratio Fertilizer Label The fertilizer ratio refers

All reputable commercial fer- I to the fertilizer's relative pro- tilizerscarry a label, stating their portions of N, P205, and K20. 1. 12- nutrientcontent, not only of N-P-K, 24-12 fertilizer has a 1:2:1 ratio, but alsoof any significant amounts and so does 6-12-6; it would take of sulfur, magnesium, and micronutri- 200 kg of 6-12-6 to supply the same ents. asiount of N-P-K as 100 kg of 12 -24- The Three Number System: This 12. Both 15-15-15 and 10-10-r0 have states the content of N-P-K in that a 1:1:1 ratio. order, usually in the form of N, N, P205, K20 versus N, P, K: Note 15705, and K20. The numbers always that a fertilizer'sNcontent is refer,to percent. A 12-24-12 fer- expressed. as N, but that the P and tilizer antains 12 percent N,-24 K content is usually expressed as

percent P205, and 12 percent K0 152 0 and KO. This system dates 2 5 2 back to the advent of chemical fer- which is the same as 12 kg N,24 kg P205 and 12 kg K20 per 100 kg. A tilizers in the 19th Century and is 0-21-1 fertilizer has no nitrogen still used by most countries, al- or potassium, but contains 21 per.- though a few have switched to an N- cent P205. Here are some more ex- P-K basis. A fertilizer recommenda- amples: tion given in terms of "actual P" 300 kg 16-20-0 contain 48 kg and "actual K", refers to the new N,'60 kg P2 05,-0 kgK20:1 system; check the fertilizer label 250 kg 12-18-6 contain30 kg to see if the nutrient content 'is N, 45 kg P205, 0 kg K201, given as N-P205- K20 or as N-P-K.

rj 151 162 The formulas below show bow to convert between the 2 systems: Basic Guidelines P X 2.3 = P0 P0 X 0.44 25 25 For Applying 1(20 X 0.83asI( K X 1.2 = K0 2 Chemical Fertilizers

For example, a fertilizer with a 14-14-1.4 N-P205-K20 label would be labelef 14-6.2-11.6 on an N-P-K basis. Likewise, if a fertilizer recommendation calls for applying . Nitrogen 20 kg of "actual P" per hectare, it would take 46 kg (i.e. 202.3) of When fertilizing maize, sor-

P0to supply this amount. Table gbh, and millet, one-third to one- 25 6 gives the nutrient content of half of the total N should be ap- common fertilizers. (Refer to pages plied at planting time. This first

74-78 of PC/ICE'S Soil, Crops and application will usually be in the Fertilizer Use manual for more de-. form of an N-P or N-P-K fertilizer.

tailed information.) -0 The remaining N should be applied in one to two sidedressings (fertilizer applications made along the row whi e the crop is growing) later on in the growing season when the p ants' N usage has increased. A straiem N fertilizer like urea (45-46 percent N) , ammonium sulfa e (20-21 percent N) or am-, monium n trate (33-34 percent N) is recommen ed for sidedressings. When one sidressing is to be made, it 0

152 4:63 Table 6 COMPOSITION OF 'COMMON FERTILIZERS NITROGEN §OURCES N % P0 % K 0 % S % 25 2 Anhydrous ammonia (NH 82% 0 .0 0 3) Ammonium nitrate 33% 0 0 0 hmmonium nitrate with lime 20.5% 0 0 0 Ammonium. sulfate 20-21% 0 0 23-24% Ammonium phosphate 16% 20% 0 9-15% sulfate (2 types) 13% 39% 0 7%

,.. Mono-ammonium phosphate 11% 48% 0 3-4% (2 kinds) 12% 61% *0 0 .. Di- ammonium phosphate 16% 48% 0 0 (3 kinds) 18% 46% 0 0 21% 53% 0 0 Calcium nitrate 15.5% 0 0 0 Sodium nitrate 16% 0 0 0

Potassium nitrate 132 0 46% 0 - Urea 45-46% 0 0 '0

1 PHOSPHORUS SOURCES

Single superphosphate 0- 16-22% 0 : :8-12% Triple superphosphate 0 42 -47% 0 1 -3Z Mono-8 di-ammonium phosphates (see under N) Ammonium phosphate sulfate (see under N)

POTASSIUM SOURCES

Potassium chloride 0 62% 0

_ .(muriate of potash)

Potassium sulfate . 0 0 50-53% 18%

Potassium nitrate 132 0.. 44% 0 /% P6tassium magnesium 4 0 0 21-22% 18% sulfate (11% Mg, 18%.Mg0) NOTE: .P205 X 0.44 T P; K20 X 0.83 T K; S X '3.0 T SO4;

4. 153 164 . is usually best applied when the' 20 cm or more out from the plants. crops are about knee-high (25-35 Crops with spreading root systems days after plant emergence in warm like maize, sorghum, and millet can areas). On very sandy soils or un- be sidedressed mid-way between the der high rainfall, two sidedress- rows with no loss of effect. There ings 'nay be needed and are best ap- is no need to broadcast the N to en- plied at the knee-high and flower- courage better distribution, because ing stages. .it will spread outward as it moves Where to Place Nitrogen Fertilizer downward through the soil. Avoid As an N-P or N-P-K Fertilizer: See spilling fertilizer on the crop the section on phosphorus below. leaves since it can burn them. (Fer- As an N Sidedressing: There is no tilizer burn occurs when too much need to place a straight N fertili- fertilizer is deposited too close to - zer as deep as with P and K, since the seedd or seedlings, causing rainfall Will carry the N downward them to turn brown and lose ability into the root zone. Work it in 1.0-2.0 to absorb water.). if time is short, cm to keep the fertilizer frOm be- every other row can be sidedressed ing carried away by surface water with twice the per-roW amount. flow. Urea should always be worked in to avoid loss of N as ammonia 4 Phosphorus gas.(Thr same is true for all ammonium N fertilizers when soil pH Phosphorus is virtually im-- is above 7.0.)The best time to side - mobile in the soil. This means that dress is right before a weeding fertilizers containing P should be (cultivation)- the cultivator or hot placed at least 7.5-10 cm deep to as- can then work it into the soil a sure good root uptake. The roots of bit. most crops are not very active Nitrogen can be placed in a close to the soil surface (unless .continuous bind along the crop row some form of mulching is used)

154 165 since the so0.1 dries out so readily. ing P, even if they plow or hoe For these reasons, all the P ferL- them into the ground. Broadcasting tilizer should be applied at p ant- maximizes P tie -up /by spreading the ing time:.. fertilizer too sparsely and exposing Young seedlings need hie" each granule to fUll soil contact. concentration of P Broadcasting gives a much better their tissues for gopd early growth and root develop- distribution of P throughout the ment. topsoil, but very high rates are Phosphorus does not leach, needed to overcome tie-up and few so there Is no need to make additional sidedress- small farmers can afford them. In ings. fact, it takes about two to ten To be effectiv,as a side- times as much broadcast P to produce dressing, P would also need to be placed deep (except the same effect as an equal amount of heavily mulched-sOit)v-- on a locally placed P. Instead, farmers and this ',eight damage the

roots. / should use one of the localized NOTE: Many farmers waste mo4y by placement methods described below. .sidedressing with N-P, N-P-K P Concentrating the fertilizer in fertilizers after already apily-- ing P at planting. Others do not a small area enables it to over- apply P until the crop is several come the tie-up capacity of the weeks old. In either case, crop yields suffer. immediate surrounding soil.

How to Minimize Phosphorus Tie-4p Adding large amounts of organic Only about 5-20 percent of matter to the soil helps decrease

the fertilizer P that the farmer'ap- P tie-Up, but usually is not feas- plies will actually become available ible on largefields. Soil pH to the growirig crop. App..ication should be maintained within the 5.5- method has a influence on the 7.0 range if possible. Very acid

amount of tie4.up that occurs. soils have an especially high Ptie - In general, farmers should up capacity. When P is applied as not broadcast fertilizers contain- an N-P or N-P-K fertilizer, the N

155 160 helps increase the uptake of P by b. Plow or hoe methods the plant roots. The farmer can make a furrow 7.5-15 cm deep with a wooden Placement of P Fertilizers plow or hoe, apply the fer- Continuous band method: This is the tilizer by band along the bottom, then kick in enough best method for the reference crops soil to fill the furrow back and is,especially well suited to closely up to planting depth. This gives a band of fertilizer spaced drill plantings. The op- running under the seeds and timum location of the band is a little to each side. As long as there is 5.0-7.5 cm 5.0-6.0 cm to the side of the seed of soil separating the fertilizer and the seeds, there row and 5.0-7.5 cm below seed level. is little danger of burning. One band per row is sufficient. A less satisfactory method How to make a band: The farmer has is to make one furrow at planting depth and place both a couple of choices:, seed and fertilizer in it a. Fertilizer band applicators are together (the furrow should' be wide so the fertilizer available for most models of trac- can be spread out and dilut- tor drawn planters and for some ed somewhat). This works with maize at low to medium rates animal-drawn planters. Hand-pushed of N and K (no more than 200- band applicators are also available 250 kg/ha of 16-20-0 or 14 -14- 14; no more than 100-125 kg commercially. The International ha of 18-46-0 or 16-48-0). Institute for Tropical Agricul- Higher rates may cause fertilizer burn. Beans and ture (11TH) farming systems program sorghum are more sensitive has designed a hand-pushed model to fertilizer burn than *maize. that can be.. built in any small work- Half-circle Method: Works well shop with welding and metal shear- when seeds are planted in groups ing capabilities. However, it is not ("hill planting") spaced relatively clear from the design whether the far apart on untilled ground where IITA model actually places the fer- banding would be impractical. The tilizer below the soil surface. fertilizer is placed in a half-

156 circle made with s machete, hoe,or and stalks rather than in the grain. trowel about 7.5-10 cm away from each Returning crop residues to the soil seed group and 7.5-10 cm deep. This is a good way of recycling K. Burn- is time-consuming, but gives a bet- ing them will not destroy the K, ter distribution of fertilizer than but will result in the loss of the hole method. theft N,, sulfur, and organic matter. Hole method:: This is the least effective of the three methods, but is Some Special Advice much better than using no fertilizer For Furrow-Irrigated Soils at all. It.may be the only feasible method for land that has been hill planted without any prior tillage. When using the band, half- circle or hole methods on furrow Fertilizer is placed in hole 10-15cm irrigated soils (crops irrigated by deep and 7.5-10cm away from each seed group. conveying water along a furrow bet-

0 weer each row or bed) the farmer Potassium should be sure to place the fertilizer below the level that the Potassium ranks midway bet- irrigation water will reach in the ween N and P in terms of leaching furrow. Placement below this "high losses. As with P, all the K can water" mark enables mobile nutri- usually be applied at planting time, ents like nitrate and sulfate to often as part of an N-P-K fertili- move sideways and downwards toward zer. Where leaching losses are like- the roots. If placed above the ly to be high (very sandy soils or water line, the upward capillary very high rainfall), split applica- movement, of water will carry these tions of K are sometimes recommend- mobile nutrients'to.the soil sur- ed. face where they cannot be used. Unlike N and P, about two- (Upward capillary movement is the ' thirds of the K that plants extract same process that enables kerosene from the soil ends up in the leaves to "cline up the wick in a lamp.) 1681 157 Determining How NOTE: Rather than tell farmers to Much Fertilizer apply so many, grams or ounces per To Use length of row or per hill, convert the weight dosage to a volume dosage using a commonly available container The following table can be like a tuna fish or juice can, jar used to determine how much fertilizer, lid or bottle cap. to apply per length of row (if the. Fertilizers vary in density, half-circle or hole method is used). so be sure to determine the weight/ (The formula found in PC /SCE's Soil, volume relationship for each type Crops and Fertilizer Use manual can using an accurate scale. also be used to determine this amount.)

Table 7 Determining How Much Fertilizer is Needed per Meter of Row Length or per "Hill"

I. Per Meter of Row Length (For band applications): AMOUNT OF FERTILIZER NEEDED PER HECTARE.

Row 100 kg 200 kg. 300 kg_ 400 kg-._ 50C kg 600 kg Width GRAMS TO APPLY PER METER OF ROW LENGTH

50 cm 5 . 10 15 20 25 30

60 cm 6 42 18 24 30 36

70 cm 7 14 21 28 35 42

80 cm 8 16 24 32 40 48

90 cm- 9 18 27 36 45 54 100 Cm 10 20 30 40 50 60

158

169 Ii. Per Hill (For half-circle or' ammonium nitrate, and di-amonium hole applications): Inthis case, phosphate are also soluble enough for the amount depends on the row spacing this purpose. However, only small and the distance between hills in the amounts of fertilizer can be sprayed row. The table below shows how many on the leaves per application without grams of fertilizer are needed per causing "burning" - this means thit hill to equal a rate of 100 kg/ha. To foliar applications are usually best find out how much would be needed to suited for micornutrients of which equal a rate of 250 kg/ha, you would very little is needed. Foliar appli- multiply the table's figures by 2.5. cations are especially useful for

DISTANCE BETWEEN HILLS Row 30 cm 40 cm 50 cm 60 cm 70 cm 80 cm 90 cm 100 cm Width GRAMS OF FERTILIZER NEEDED PER HILL TO EQUAL 100 KG/HA 50 cm 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 60 cm 1.8 2.4 3.0 3.6 4.2 4.8 5.4 6.0 70 cm 2.1 2.8 3.5 4.2 4.9 5.6 6.3 7.0 80 cm 2.4 3.2 4.0 4.8 5.6 6.4 7.2 8.0 90 cm 2.7 3.6 4.5 5.4 6.3 7.2 8.1 9.0 100 cm 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

applying iron, which becomes readily Foliar Fertilizers tied up and unavailable when applied to the soil. Although foliar-applied Foliar applications are best fertilizers take effect rapidly suited for micronutrients: Soluble (within one to three dais) they have powder or liquid fertilizers may be much less residual value than soil, sold in some areas for mixing with applications. water and spraying on the leaves. Some granular fertilizers like urea,

159 N-P-K foliar fertilizers are How to Avoid often claimed to produce very profit- Fertilizr "Bu" able yield increases. Numerous trials have shown that N-P-K foliar fertilizers Fertilizer "burn" occurs when usually "green up" the leaves but significant yield increases too much fertilizer is placed too are unlikely as long as suff i- close to the seeds or seedlings. It cient N-P-K is applied to the soil. A 1976 International is caused by a high concentration of Center for Tropical Agricul- soluble salts around the seed or ture (CIAT) trial in Colombia did obtain a 225 kg/ha yield roots which prevents them from absorb- increase on beans by spraying ing water. The seeds may germinate them three times with a 2.4 percent solution (by weight) poorly from tips downward, the seed- of mono-ammonium phosphate ling leaves may begin to-turn brown, (11-48-0) even though 150 kg/ha of P0 had been added to the and the plants may die. 25 soil. (The'spray contributed Guidelines for Avoiding Fertilizer only about 10 kg/ha of P20,.) However, the soil had a vefy Burn high P tie-up capacity. The N and K in fertilizers have a much higher "burning" The soluble powder and liquid ability than P. Single and foliar fertilizers are much triple superphosphate are very more expensive per unit of safe. Sodium nitrate and po- nutrient compared to ordinary tassium nitrate have the high- granular fertilizers. est burn potential per unit of plant nutrient followed by Numerous applications are ammonium sulfate, ammt ;um ni- usually needed to supply a trate, mono-ammonium phosphate, meaningful amount of N-P-K (11-48-0), and potassium through the leaves without chloride. Di-ammonium phosphate risk of burning. (16-48-0, 18-4670) and urea can Some N-P-K foliar fertilizers injure seeds and seedlings by have micornutrients included releasing free ammonia gas. but the amounts are far too The higher the ratio of N and small for preventing or curing K to P in an N-P-K fertilizer, deficiencies. the greater the likelihood of burning due to improper placement.

160

37.E When using fertilizers con- Small'farmers should usually aim for taining N, do not place maximuWreturn per dollar spent. This them any closer than 5 cm to the side of the seed row when means using low to-moderate rates of banding and 7.5 cm when using fertilizer because crop yield response the half-circle or hole methods (see exceptions dis- is subject to the law of diminishing. cussed under banding methods). returns.'' There is little danger of burning when sidedreising Since the efficiency of ferti- growing crops with N, but lizer response declines as rates go up, avoid dropping the granules on the leaves. the small farmer with limited capital Fertilizer burn occurs more is usually better off applying low to frequently on sandy soils medics& rates of fertilizer. He or tan on clayey soils and under low moisture conditions.she will end up with a higher return A heavy rain or irrigation per dollar invested, be able to ferti- will help carry damaging salts away if burning occurs. lize more land, and have money left over to invest in other complementary Recommended yield-improving practices. ' As a farmer's capital situation Fertilizer Rates improves, higher rates of fertilizer For the Reference may be justified as long as investments in other worthwhile practices are not Crops sacrificed. Another factor to consider is that fertilizer can reduce the land and labor needed to produce a given The most profitable rate of amount of crop, thus cutting costs and fertilizer use for the small farmer allowing for more diversity of pro- depends on management ability, capi- duction. tal available, limiting factors, soil, fertility level, type of.crop, expected price and cost of fertilizer.

161 172 Some General There are several important qualifi- Guidelines for catlions to Table 8: Low, Medium and ,High Rates YOU MUST CONSIDER THE FERTI- " Of N-P-K ILITY LEVEL OF THE SOIL as well as the type of crop.A soil high in available K would Keeping in mind the many need little or no fertilizer K. Most cropped soils tend to be factors that determine optimum ferti- low in N and low to medium in P, but K deficiencies are less lizer rates, Table 8 provides a very common. Peanuts often respond general guide to LOW, MEDIUM, and better to. residual P and K rather than to direct applica- HIGH rates of the "Big Three" for tions. the reference crops based on, small Legumes such as peanuts,-cow- nrmer conditions and using localized peas, soybeans, pigeonpeas,' mung beans, and chickpeas are placement of P. The "high" rates very efficient N fixers if given here would be considered only properly innoculated with the correct strain of Rhizobia low to-medium by most farmers in bacteria or if grown on soils Europe and the U.S. where applica- with a good natural population of the correct Rhizobia. In tions of 200 kg/ha of Nare not some cases, however, a starter uncommon on maize and irrigated application of 15-25 kg/ha of N has given a positive response Aorghum.

Table 8 General guidelines for low, medium, and high rates of N-P-K LOW MEDIUM HIGH (Lbs./acre or (Lbs./acre or (Lbs./acre or kg/hectare) kg/hectare) kg/hectare)1 2 N 35-55 60-90 100+

P0 25-35 40-60 70+ 25 K20 30-40 50-70 80+

1. When inter-converted, lbs:/scre and kg/ha are nearly equivalent at least tor the purposesof this general table. kg/ha x 0.69 = lbs./acre.

162

4. 17 by feeding the.plants until shelled maize should increase by the Rhizobia begin to fix N roughly 25-50 kg for each kg of-N (about two 0 three weeks after plant emergence). such applied up to a yield of around 4000- responses are the exception 5000 kg/ha. With higher rates of appli- rather than'the rule and are most likely to occur on sandy cation, response generally falls below 44 soils. this ratio. Such yield increases will Beans (Phaseolus v24garis) are be obtained if: not so efficient at M-fixation and can use up to 5Q-60 kg/ha Other nutrients like.P and K of N. are supplied as needed, soil moisture is adequate, a respon- The farmer's managemerit ability e sive variety is used, and there is a vital consideration. Far- are no serious limiting factors mers should not be encouraged such as insects, diseases, weeds, to use a high rate of fertili- soil ph, drainage, etc. zer if he or she is not willing or able to use other comple- The fertilizers are applied mentary yield-improving prac- correctly and at the right time. tices. If response falls velow the 25-50 level, this means that one or more Fertilizer serious limiting factors is present or Recommendations that too high an N rate was used. Table 8 can be used as ,.a guide, For Specific but soil should be tested whenever Crops possible. Studies have shown that maize can use locally-placed (band, half-circle, hole) P efficiently up to Maize about 50-60 kg/ha of P205. Micronutrients: Except for zinc, maize is not very susceptible to micronutrient

Fertilizer Response deficiencies. When starling from a low yield Zinc deficiency can be confirmed base like 1000-1500 kg/ha, yields of by spraying about 20 plants with a

163 174 solution of ,one tablespoon (15 cc) wetting agent. If zinc is the only 'zinc sulfate in abut four liters nutrient lacking, new leaves will of water along witabout 5 cc of have a normal green color when they liquid dishwashing detergent as a emerge.

Table 9 Zinc Source % Zinc Amount Needed Application Method Zinc sulfate 23% 8-12 kg/ha mixed with planting ferti- monohydrate (lbs./Acre) lizer and locally placed Zinc sulfate 35% 6-9 kg/ha mixed with planting ferti- heptahydrate (lbs./acre) lizer and locally placed Zinc oxide 78% 2.5-4 kg/ha mixed with planting ferti- (lbs./acre) lizer and locally placed Zinc sulfate 23%, 352 350-500 grams/ Foliar; spray the leaves; 100 liters watermay cause leaf burn under plus a wetting some conditions. agent

Iron deficiencies seldom respond well Sorghum to iron applied in the soil unless special chelated (organic and more costly) forms are used to protect

Fertilizer Response: Sorghum will against tie-up. Deficiencies should give similar fertilizer responses to be treated 1.1 spraying the plants with maize if moisture is adequate and a solutior_of 2-2.5 kg of ferrous sta- . improved varieties are used. As fate dissolved in 100 liters of water always, farmers should be encouraged along with sufficient wetting agent to to test the soil first rather than assure uniform leaf coverage. Begin rely on general recommendations. spraying as soon as symptoms appear; Nutrient needs are similar to the plant may need several applica- those of maize,* except that sorghum tions duping'ehe growing season on is most susceptible to iron deficiency. -severely deficient soils.

L64

17 .Sorghum seeds and seedlings ture and variety factors. are more sensitive to fertilizer burn than maize. If more than one Peanuts grain harvest is to be taken from one planting, all the P and .1( should ' be applied at planting along with about 30-50 kg/ha of N. Another Fertilizer Response,: Peanuts tend to ressing of 30-50 kg/ha of N should begive rather unpredictable responses to pplied about 30 days later. After fertilizer and of ter respond best to tie first. harvest, apply an additional:residual fertility from previous

3 T50 kg /ha 25 -30 days later. applications to other.crops in the rotation. Miirt Nitrogen and Nodulation: If the right strain of Rhizobia bacteria is . present, peanuts can ordinarily satisfy their own N requirements. There are Fertilizer Response: Low soil mois- two exceptions: ture is a major factor limiting If poorly drained portions of 1 fertilizer response. Traditional the field *become waterlogged temporarily, the Rhizobia may varietiesare usually less responsive. die-off and the plants begin An applica- Studieg in India by ICRISAT showed to turn yellow. tion of 20-40 kg/ha of N may that im?roved pearl millet varieties/ be needed to carry the plants were responsive to N rates as high .through until the bacteria become re-established in as 160 kg/hectare under several weeks. moisturei but 'that traditio type? In some cases (mainly on light- colored, sandy soils), 20-30 kg/ seldom responded well above the 40-1 ha of N applied at planting has 80 kg/hectare range. The N-P-K rates seemed to help the plants esL tablish themselves until the in Table 8 can be used as a guide, 1 Rhizobia begin to fix N abut taking into consideration the mois-

165 176 ii

three weeks,after emergence. Phosphorus and Potassium: Because This is not] widely recommended. peanuts have an unusually good abi To check for proper nodulation, to utilize residual fertilizer,fr carefully remove the roots of plants preceding crops, they do not res ond at least three weeks old and look well to direct applications of P and for clusters of fleshy nodules (up to K unless levels are very low. In the size of small peas) especially fact, there isgood evidence that high around the tap root. Slice a few K levels in the podding zone ian in- open - if they are reddish inside, crease the number ofpops(unfilled this shows they are actively fixing kernels) due to decreased calcium N. availability. Seed Innoculation is normally not Calcium: Peanuts areone of the few * necessary if peanuts are sown on crops having a high Co requirement. , land that has grown peanuts, co eas, Light green plants plus a high per-

' lima beans, mung beans or crota aria centage of pops may indicate Ca within the past three years. mmer- hunger. Calciumdoesinotmove from cial innoculant is a dark -cold ed, the plant tothepodis;/rather, each dried powder which contains the living pod has to absorb its own require- Rhizobia and comes in a sealed packet. ment. Gypsum pcalcium sulfate) is Seed is placed in a basin and mois ten- used to supply Ca to peanuts because \ tied with water to help the innoculant\ it is much more soluble than lime and stick (adding a bit of molasses helps,\has no effect on soil p14 (using lime too). The correct amount of inno- to supply Ca caieasily raise the p14 culant is mixed with the seed, and too much)."The usdal application planted within a few hours. Exposing where'deficiencies exist is 600-800 kg/ the seed to sunlight can kill the ha of dry gypsum applied right over bacteria. the center of the crop row (it will not "burn") in a band 40-45 cm wide any time from planting until flowering.

166'

1 7 7 I

Gypsum also supplies sulfur. recommended N rates usually fkll in Micronutrients: Boron and manganese the range of 40-80 kg/ha N. In a 1974 aze theones most likely oo be deft- CIAT trialein Colombia, 40 kg' /ha N . cient (see Table 5). Boron can be increased yields to 1450 kg/ha compared toxic if applied at rates much above to 960 kg /ha with no N. It was found those given in Table 10 especially that acid forming fertilizer N sources when banded. such as urea and ammonium sulfate cold increase the chances of aluminum

Tabla 10 41* )Suggested Boron (B) and Manganese (MN) Rates For Peanuts on DeficienX Soils Material % B or Mn Amount Needed How Applied. Borax 11% B 5-10 kg/ha Mixed with fungicide dusts forlleafspotor mixed with gypsum. Do not locally place boron or injury may result.

Solubor 206 B 2.75 kg/ha Spray pianos - Manganese 26-28% Mn 15.20 kg/ba Banded with row fertilizer sulfate at planting Soluble man- 26-28% Mn 5 kg/ha Spray on plant'leaves; ganese sulfate use wetting agent. Manganese 26-28% Mn 15 kg/ha Dust the plants with the sulfate finely ground form

Beans and .manganese toxity if bandednear the (Kidney Beans) row on very acii soils. It was recommended`that,the N be spreadout more in these cases. Nitrogen: Beans are less efficientN Phosphorus: 'Beans have a high P rem 'fixers than peanuts or cowpeas and quirement, and this is often the

167 178 4 a 4g

major limiting nutrient, especially lished cropsc_i on soils with a high capacity to tie Micronutrients: Beans are most sus- up P. A 1974 CIAT trial on such a ceptible to manganese, zinc, and soil resulted in yields of 700 kg/ha boron deficiencies (see Table 5). without P and 1800 kg/ha when 200 kg/ Varieties differ in their suscepti- - ha of P0was banded along therow.t bilities. 25 Such high rates of P may be needed Zinc rates: As for maize. on soils with serious P tie-up Manganese: As for peanuts. problems. Under such conditions, it Boron: 10 kg/ha of borax banded with might take 10 times this amount to the row fertilizer at planting or 1 kg give the same effect if,broadcast. Solubor (20 percent B) per 100 liters Potassium deficiencies are uncommon of water sprayed on plants. in beans. Manganese toxicity is sometime's a pro- Magnesium defiCiency may occur in blem on very acid soils, especially if very acid soils or those highin they are poorly drained. Symptoms are Ca and K. It can be controlled by easily confused with those of zinc and applying 100-200 kg/ha of magnesium magnesium deficiency. Beans are also sulfate or 20-30 kg/ha or magnesium very sensitive to aluminum toxicity oxide to the soil. If the soil needs which occurs below a pH of 5.2-5.5, liming, us.ng dolomitic limestone and liming the soil is the only control. (20-45 percent Mg) will solve the aluminum toxicity is severe, plants problem. Dolomitic limestone and may die shortly after emergence. In magnesium oxide should be broadcast more'moderate cases, the lower leaves and plowed or hoed under before become uniformly yellow with dead plantingMagnesium sulfate (epsom margins, the plants become stunted, and slats) can be band-applied or side- yields can be lowered dramatically. IF dressed. A foliar application of one kg magnesiumsulfate per 100 liters water can be tried on estab-

168

379 Cowpeas Very acid soils are usually low in available P and have a high

. capacity to tie up added P by Well-nodulated coWpeas do not forming insoluble compounds respond to N applications, although with iron and aluminum. Although very acid soils usually 2a starter dosage of 10 kg/ha N some- have enough calcium to supply timeS shows results. plant needs (except for peanuts), they are likely to be low in magnesium and available sulfur and molybaenum. Liming Low soil pH depresses the acti-, vities of many beneficial aoil microbes such as those teat convert unavailable N, P, and S to available mineral forms. Maize and cowpeas may tolerate- .soil acidity in the pH 5.0-5.5 range

Soils with pH below 5.0-5.5 depending on the soil's soluble alumi- (depending or the soil) can adversely num content. Sorghum is somewhat more affect crop growth in four ways: tolerant than maize to soil acidity. Aluminum, manganese, and iron Peanuts commonly do well down to pH toxicities: These three ele- 4.8-5.0 since they have comparatively ments increase in sulubility 3s soil pH drops and may good aluminum tolerance. Beans are actually become toxic to the most sensitive of the reference plants at pH's below 5.0-5.5. Beans are especially sensitive crops to soil acidity,, and yields to aluminum toxicity which is usually decline below a soil pH of the crop's biggest yield limiting factor in some areas. 5.3-5.5. Many soils labs routinely test for 'soluble aluminum levels in very acid samples. Manganese and iron toxicities can be serious, too, but usually are not a problem unless the soil is also poorly drained.

.169 1Ci0 Where are Acid drawbacks: Soils Likely To be Found? Soil _ph is not the sole criteria for determining if liming is needed. The soil's content of soluble aluminum (called "exchangeable" aluminum) is pro- Soils in higher rainfall areas bably even more important, and are likely to be slightly acid to the portable pH kits cannot strongly acid since a good deal of measure this. A soil with a pH of 5.0 or even lower might calcium and magnesium may have been still be satisfactory for the leached out over time by rainfall. growth of most crops if its exchangeable aluminum content Those of drier regions are likely is low. On the other hand, another soil with a pH of 5.3 to be alkaline or only slightly acid might need liming because of due to less leaching. too much aluminum.' Only the Continual use of nitrogen fer- soils lab can tell for sure. The amount of lime needed to tilizers, whether chemical or organic raise soil p11 one unit varies will eventually lower soil pH enough greatly with the type of soil involved. One soil may require to require liming. Calcium nitrate, 8-10 times more lime than potassium nitrate, and sodium nitrate another to achieve the same rise in pH even though both have the are the only exceptions and are same initial pH. The amount of usually too expensive or unavailable. lime needed depends on the soil's amount of negative charg.; which varies with its texture, type How to Tell if of clay minerals, and amount Liming jsNeeded of humus. Only the soils lab can determine this. Calculating the Amount of Lime Soil pH can be measured fairly Needed' accurately right'in the field with a Whether using the lab's or, other liquid.indicator kit or a portable recommendations, adjustments still must electric, tester. These are useful be made for the finAness. Purity, and for troubleshooting but have two neutralizing value of the material used: drawbacks:

170

1 81, Neutralizing value: On a more Harrowing alone only move pure basis, here are the neu- the material down about half tralizing values of four liming this distance. A disk plow materials: or moldboard plow should be Material Neutralizing Value used, not a wooden or chisel plow. If spreading lime by (compared to limestone) hand, the amount should be Limestone 100 percent divided in half and one por- (calcium carbonate) tion applied lenghtwise and Dolomitic limestone 1 09 percent the other widthwise., Wear a (Ca + Mg carbonate) mask hydrated (slaked) lime Hydrated lime 136 percent and burned lime can cause (calcium hydroxide) severe burns. Burned Hine 179 percent (calcium oxide) Whenever possible, a dolomitic form of liming material should This means that 2000 kg of be used to avoid creating a burned lime has about the magnesium deficiency. same effect on pH as 3580 kg of limestone Of equal purity Liming materialt should be: (2000 kg x 1.79 = 3580pkg). applied at least two to six

it, months ahead ofplanting, es- Fineness of material greatly pecially if the materiel is affects the speed of its not well ground. reaction with the soil. Even finely ground materialinay Liming may be needed every two take two to six months to to five years on some soils, affect soft pH. especially if high rates of nitrogen fertilizers, manure Purity; Unless the material or compost are'used. Sandy has a label guarantee, it is soils will need more frequent difficult to judge purity with liming than clayey soils since a lab analysis. they have less buffering capacity, but sandy soils also will How, When, and require lower rates. How Often To Lime DO HOT OVERLIME: Never raise thepH of soil above 6.5 when liming. a, Lime should be broadcast unk- Never raise the pH by more than formly over the soil and then one full unit at a time (i.e. thoroughly mixed into the top from 4.6 to.4.6, etc.)..It is 15-20 cm by plowing or hoeing. - only necessary to raise the pH up to 5.5-6.0 for good yields

r 171 182

(3, of an aluminum sensitive crop. cereals, followed by sorghum, and 4 like beans. then maize. Of the pulses, Co4s.as Overliming can be worse than not Um- and peanuts are superior to common , ing at all fur several reasons: beans in Ihis-respect.' Raising the pH above 6.5 in- Critical Water Demand Periods:The creases the likelihood of micronutrient deficiencies, espec- critical water demand period. fox all laity iron, manganese, and zinc; the reference crops in terms of both molybdenum is an exception. yield effect and maximum usage occurs Phosphorus availability starts declining once pH rises much from flowering_time through the soft- above 6.5 due to the formation dough grain staged Under low humid- of relatively insoluble calcium and magnesium compounds. lty and high heat, total water usage Liming stimulates the activity (soil evaporation and plant transpir- of soil microbes and increases ation) may reach 9-10 mm per day dur- the-loss of soil organic matter by decomposition:, ing flowering and early grain filling. Effect of Moisture Stress on Yields: Crops can often overcome the effects of moisture %trest occurring early in the seasqp, but yields can be Water Management markedly lowered.if it occurs during flowering and grain lilling. With maize one two days of wilting dur"- ing tasseling time can lower yields Water Needs of by up to 22 percent and six to eight The Reference Crops days by 50 percent. Symptoms of Moisture Stress Maize, sorghum, and millit will begin to roll their

Relative Differences:Millet has the m, leaves up lengthwise, and the best droUght resistance of the three plants will turn a bluish-

172 l 83 green color. The lower leaves Keeping Rainfall Records will often dry up and die. (This is referred to as Since rainfall amount and "firing" and is really a distribution have such a grert drought-induced nitrogen effect on crop yieldNit is very deficiency.) The.pulse crops will also useful to keep rainfall records turn a bluish -green and at various locations in'your work their leaves will wilt as area. stress increases. "Firing" The more progressive client may also occur. farmers should be encouraged to Factors Influencing the Likelihood keep their own record's. of Moisture Stress: Judging Rainfall: Showers that Rainfall pattern.and quantity: produce less than 6 mm usually con- S4e the section on rainfall . tributelittle moisture to the in Chapter 2. crop since they do not penetrate Soil texture: This has a big influence on a soil's the soil very deeply and are quickly water st Age capacity. Clay evaporated. Imams and clay soils can For example, 5 mm of hold twice as much available rainfall will penetrate only about water per foot of depth as 20 mm into a. dry clayey soil and sandy soils. 40 mm into a dry sandy soil. Soil Depth: Deep soils can store more water than shallow soils ..:id allow greater Improving Water rooting depth for utilizing Use Efficiency it. Soil Slope:Much water can be lost by runoff on sloping In areas with short rainy soils. seasons, the use of early maturing Temperature, Humidity, and varieties is a valuable tactic. Wind: The higher the temperature and wind and the Planting dates should be timed so lower the humidity, the that likely moisture stress periods greater the rate of crop moisture use and soil do not coincide with critical crop even tionclnsses. stages such as pollination.

173 184 O

One study in Kenya showed a yield of low rainfall and probable moisture decrease of 5-6 percent for each stress. day's delay in maize planting after' Mulching the soil surface with the start of the rains (in an area a 5.0-7.5 mm layer of crop residues, with's short season). In areas can substantially increase yields in having wet seasons of adequate drier areas. length, but with periods of moisture'stress, some extension ser- Guidelines for Improving Water vices recommend planting two or more Use Effictency Under varieties with different maturities Furrow Irrigation to lower the.riskof total crop failure.' On sloping s,ils, soil con- . servation measures such as terracing To avoid falling behind in or ditch - and -bank systems will sig-- crop, irrigation needs, the soil nificantly imprdve water retention should 'be pre-irrigated to the full in addition to reducing soil losses. depth of maximum expected root r Weed control both during and between development before planting the crop. crops will cut water use. In semi- Moisture etored in the subsoil is arid areas such as the Sahel, deep usually safe from evaporation losses plowing_ should be' avoided if the unless the soil cracks'upon drying. subsoil is moist. Fertilizer use Leaching losses will be negligible will increase moisture use effi- if the correct amount is applied ciency by encouraging deeper root- since only excess water moves down- ing. *However, crops cannot utilize ward by the foyee.of gravity - the as much fertilizer (especially N) rest is held by the soil pores. when water is a limiting factor. Frequent, shallow irrigation Optimum plant populations should be avoided since it-increases are usually lower under conditions evaporation losses and limits the depth of root growth. Shallow Irrigation encourages the builcr epu of harmful salts in dry climates, and frequent irrigation favors the spread of fungal and bacterial di seases. However, irrigation may have to be fairly frequent in the initial stages of crop growth until the plants have been able to put their roots down sufficiently.

4 175 18o va

6. Pest and Disease 4 -Control

Weed Control

How Weeds Lower Crop Yields

Numerotis trials in the U.S. Of course, all farmers weed have shown maize yield losses. their fields to some extent, but ranging from 41-86 percent when most of them could significantly weeds were not controlled. One increase their crop yields if they trial in Kenya yielded only 370 did a more thorough and timely job. kg/ha of maize with no weed control A University of 'Illinois (U.S.)'" compared to 3000 kg/ha,for clean, trial showed that just one pigweed weeded plots. A CIAT trial with every` meter along the row reduced beans in Colombia showed a yield maize yields by 440 kg/ha. By the drop of 83 percent with no weeding. time weeds are only a few inches

O 177 187 tall, they havealready affected SomeImportant Facts on Weeds crop Yields. Weeds lower crop yields inseveral ways: for it They competewith the crop Broadleaf versus GrassyWeeds water, sunlight,and nutrients. Broadleaf weeds have wide(broad They harborinsects, and some or oval-shaped)leaves with veins weds are hosts for cropdiseases that form a feather-likepattern. (especiallyviruses). Grassy weeds are truerasses and Heavy infestationscan seriously have long, narrowleaves with veins interfere withmachine harvesting. that run up and downin a parallel (witch- A few weedslike Striga pattern. A few weedslike nutsedge weed) are parasiticand cause (nutgrass) belong toneithercategory, and loss of yellowing, wilting, but are sedges, allof which have crop vigor. triangular stems. Some chemical ability, of the Relative competitive herbicides are moreeffective on like reference crops: Slow starters broadleaf weeds, whileothers give peanuts, millet,and sorghum compete better control of grassytypes. during the first poorly with weeds How Weeds Reproduceand Spread: growth. Low growing few weeks of Annual versusPerennials . bush beans, and craps like peanuts, Annual weeds live only ayear however, arefairly bush cowpeas, they or so andreproduce by seed; suppressing further effective at weeds in many a enough are the most/common weed growth oncethey are big In the tropics,annuals spaces. fields. to fullyshade the inter-row rainfall may. live morethan a year if growing -weeds thatwere However, tall- Most annualsproduce controlled earlier can is sufficient.. not adequately of seed; some'of if tremendous amount easily overtakethse "short" crops 3iwhich may not ge inate for years. allowed to continuegrowing.

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Rough Pigweed, Redroot (Amaranthus retroflexus) An example of an annual broadleaf wend; reproduc.tion iA by seed.

Yellow Nutgrass (Cyperus esculentus) An example of a sedge- a type weed. The main stems- orsedges are triangular in shape. This partitular type reproduces bye seed _ as well as producing underground "nuts'," which sprout into new plants.

Bermuda Grass, Devil- grass (Cynodon dactylon) An example of a perennial grassy weed; reproduction is by'above-ground runners ,called stol' -s aswell as by. seeds. A

179 When the soil is stirred -with a hoe, Identifying Weeds 1 / harrow, or cultivator to kill weeds, / one crop of them is destroyed, but more weed seeds are brought closer' Where weeds/iare being controlled to the surface where they can sprout. by hoeing or'machanical cultivation, Annual weeds shouidbe controlled the sp%ci* identification is before they produce seed. Even so, 'usually,not/important. Where permanent eradication of annual weeds 'chemical w#ed controlis used, how- . is not possible because most fields ever, the/farmerand extension contain millions of weed seeds waiting worker should have a good idea of to germinate, and the'supply is con- which specific weeds are present / tinually replenished with more seeds since herbicides do not give broad- / brought in by wind, water, animals, spectrum control. (See bibliogtaphy animal manure, and contaminated-crop-7 for sourcesLof_furtherinformation seeds. on weed identificatios.) Perennial weeds live more than two years. Most produce seed, but many also propagate by means of Weed 'Control Methods creeping, above- ground stems (itolons), and creeping underground stems .. (rhi4omes). .Hoeing or mechanical Burning cultivation may actually aid in When land is cleared by burning, spreading them around'the field. standing annual weeds are killed Many herbicides will-kill only along with weed seeds very near the topgrowth, and there is usually soil surface. However, burning will

,enough food in the underground parts not kill weed seeds or reproductive / to continue propagation. underground parts of perennial weeds

if they are deeper than 4-5cm. Furthermore, as the brush is often

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placed in windrows or piles, before Nigeria, mulching increased maize 1 burning, much of the soil may not be yitlda by 13-45 percent and greatly,. affected by the fire. Some perennial red ced the heavy labor requirement I). tropical grasses such as Guinea for hand weeding which accounts for (Panicum maximum) and speargrass 50-70 percent of the hours needed 1

(Imperata cylindrica) are actually . to grow maize in that area.

stimulated into dense regrowth by Shading (The Row Crop Prihciple) ' burning. On the other hand, weeds Arranging crops in rows Ac

0 may be less of!a problem under slash facilitates hand weeding, but also and burn farming, because the soil is makes possible"mechanical cultivation 'usually not t9rned by plowing or {weeding) with tractor or animal -

Cultivation which brings more weed drawn equipment. In addition, the '. seeds to the soil surface. rows permit the, crop to exert Mulching better shade competition against s Mulching; the soil surface will-1'a the weeds. Hoe and Machete Cultivation 5-10 cm layerii. of cr4 residues, dead . weeds or gras6 can give'very effective Weeding with hara'tools is an 1 effective method if sufficient labdri weed controlkindprovide a number of other benefit?: is available. It is common, however;$4 -0 Erosion is greatly, reduced oh fOr small farmers who rely on this, sloping oils. method to fall behind in weeding

i a Soil warr loss by evaporation anctcrop yields often suffer. r ; x ! amd runo f is greatly reduced. Animal and Tractor-drawn Cultivation In very of areas, soil tempera- Disk harrows, field cultiVators, tures arreduced to a more and spike-toth harrows can provide 1 benefici 1 level for crop excellent preplanting weed control. s growth. ThO spik5:-tooth harrow can 'lso be Organic atter is eventually used to control emerging w eds until I

added to the soil. the crop. is about 7.5-10stm tall.. 10 In trial conducted by IITA in withoutstrious damage. /

181 191 ' ... / t

Animal-and tractor-drawn row sprayers are being developed. by I1TA. . cultivators can be used from the Herbicides do have some very time the crop is a few centimeters definite disadvantages that must be, tall. They are faster than welding considered when working with small by hand, and a one-row animal -4rawn farmers: model can easily cover 3-4ba4ay They are less reliable quirt hand unless the rows arevery.narrom( tool or mechanical' weeding-and They cfn also be adjusted to throw most require careful aria accurate soll.ihtIthe row itself to kill application. This'can be achieved sma11,1410ds by burying them. If by small farmers using backpack t' operat4too deeply or too close to sprayers, but it requires some io the row, however, serious root training. pruning (cutting oir crop roots Weed control/is seldom complete. during cultivation between rows) Most herbices are not broad- may ri4sult. spectrum, a d it is important Herbicides to analyze the type.of local. Herbicides can greatly reduce weeds species present before.,; labor requirements and permit a choosing a product. farmer to grow a larger acreage. Most soil appliedherbicides] They also avoid,root.pruning; soil require a certain amount of er cOmpaction,:and -,:and reduction which rain within a week after ap-., are ceuseUby h, *tools or mechanical plication in orderto move equipment,'In a number of cases, the chemical into the zone herbicide ,like atrazine have proven of 'weed seed germination. competitive withhand labor'in maize Others need immedia4 incor- A poration.into the soil with production in.develocangcountrie..

Improve'dmethods for small farmer a!disk harrow or rototiller.

application of herbicides such as improper application may .

granular foims ant ultraldtivolume /damage the crop.

I I

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192. 67.

Nearly; all herbicides are to planting. This will give the unsuited for use in inter - young seedlings a "head start" on cropping involving cereals future weeds which.is especially and legumes due to the danger important under two conditions: of crop injury. These products Slow starters like sorghum, ire crop - specific as well as millet, and peanuts: They weed - specific.' are very vulnerable to early Without proper training and season weed competition. care, farmers may subject them- Reliance on tractor or animal- selves and the environment Lo drawn row cultivation: The serious risks through the mis- only way these cultivators application or mishandling of can control weeds in the crop these toxic chemicals. row is by throwing in soil to bury them. This means waiting until the crop is tall enough Guidelines for Non-Chemical Weed (usually over 5 cm) so that. it Control in the will not be buried too. The Reference Crops problem is that weeds already present or about to emerge in' the row at planting may be Pre-planting Weed Control able to grow tall enough to Successful weed control begins escape burial by the time with planting the crop in a seedbed cultivators can be used. free of standing or emerging weeds. Frequent pre-plant'harrowings This means that when planting on do little to reduce the field's tilled grounl (as opposed to pure potential weed population and they slash and burn agriculture), the can increase soil compaction and field should undergo some form of destroy good tilth by speeding up cultivation (i.e. plowing, harrowing, the loss of organic matter. hoeing, etc.) as close as possible

183 193 How to Use a Spike-Tooth.Harrow on weather- is cloudy, the weeds Young or Emerging Seedlings may be transplanted instead of

If large numbers of weeds emerge tilled. at the same time as the crop, The harrow should be run only shallow working of the entire soil deep enough to uproot the tiny surface (including the rows them- weed seedlings. selves) with a spike-tooth (peg- Beans and peanuts are more easily tooth) harrow may be the best, injured when they first emerge solution if hand weeding labor is and still have the crook (bend) inadequate or too expensive. This in the stem. method is best suited to crops Less injury is likely if the planted at least 40-50 cm deep and harrow is used in the afternoon can be used any time from two to when the plants are less turgid three days after planting until the (hard) and brittle. crop is 7.5-10 cm tall. Care must be taken to ensure Peanuts and beans, with their that the draft animal or the !:rittle stems, are Tore likely to be tractor tires do not run o,,er injured than maize and sorghum, the row itself. unless certain precautions are taken Using the spike-tooth harrow in (see below). Millet is usually this manner once or twice can often planted too shallowly to tolerate eliminate future, more'laborious this method well. weeding. Use of this harrow prior Guidelines for using the spike- to plant emergence is also useful tooth harrow for this type of weeding: for breaking up any soil crusting The weeds should be either just that might hinder emergence. (For emerging from the soil or still more information on the spike-tooth very small. harrow, see the PC/ICE Animal If the soil is very wet and the Traction manual.)

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194 Guidelines for Animal-and Tractor- attachments for plowing, ridging, Drawn Row Cultivators and cultivating.

Animal-drawn cultivators are Tractor-drawn cultivators widely manufactured in one-row usually consist of a toolbar to which models and cost about $100-$200 in cultivating shanks are attached. Two- U.S. currency. They are well worth row, four-row, six-row, and eight-row the investment since they permit arrangements are most common. It is more timely and rapid weeding than important to remember that such multi- is possil-le with hand tools. A one- row arrangements require _uniform row cultivator can easily weed 2-3 spacing of the planting rows to avoid hectares per day of wide row crops crop injury. such as maize, millet, and sorghum. Cultivator Shovels and Sweeps: Both Animal-drawn models are available animal- and tractor-drawn cultivators either as single-purpose units or use sweeps and/or sfioyell attached as multi- purpose toolbar frames with to the 00cultivator shanks to do the

actual weeding. Some important

considerations: Shovels require deeper soil penetration for good weed control and throw more soil than most sweeps. This means that in the case of tractor usage, shovels cannot be operated as close to the crop rows as fast as most sweeps. Sweeps are available in widths An animal-drawn cultivator which can be up to about 50 cm. However the adjusted for width by farmer is usually better off moving the upright level. using two or more sweeps of smaller widths or a combination

185 195 of sweeps and shovels to cover To avoid serious root pruning, shovels and sweeps.should be one inter-row space. This operated as shallowly and as permits more effective weeding afar from the crop row as practical. The ideal depth and more accurate adjustment than and distance will vary with is usually possible with just crop size and row width. For example, when maize is one wine sweep. Wide sweeps are 20 cm tall, it can be culti- also more prone to breakage. vated up to 10-15.cm from the stalks. However, once the Some General Guidelines for Wedding crop is 75 cm tall, such deep with Row Cultivators cultivation would prune off much of the root systems. 1. A sure sign of root pruning Maximum depth should be is the accumulation of crop about 5.0-7.5in at this roots on the cultivator shanks.

A tractor-drawn cultivator weeding beans. This particular model is mid-mounted,Which-allows-the-driver to-- view the weeding operation without having to turn around. Note the two outside shanks on the rear toolbar which help loosen the soil compacted by the tractor tires.

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196 Different types of cultivator shovel; note that some have reversible points. AAAPIIA Different types of sweep.They come in many widths. The height of the sweep's crown determines how much soil it throws. The half- sweeps are used next to the crop row to help avoid damage.

stage. Sweeps can be run 4. The nitrogon sidedressing shallower and closer to the is best applied right row than shovels and do a before a cultivation, then good job of weeding without the fertilizer can be root damage. worked into the ground a bit to prevent losses 2. Sweeps should be set to through water runoff or operate almost flat with the through conversion into tips angled just slightly ammonia gas (a problem downward. When the point with urea). rests on a floor or. the ground, the outside tips 5. Cultivation is most of the wings should rest effective when the soil about 30-4p cm off the surface is plx; wet soil surf#ce. keeps partially uprooted weeds alive. 3. Weeds should be killed early to avoid yield losses and to permit more effective control,-espWia-1-17-t-rf-weed-s right in the row.

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197 root rot. 'control), butalso helps 6. The cultivator shouldbe adjusted so that it throws promote the growth of secondary sufficient soil into the roots. This is especially beneficial crop row to burysmall weeds without smothering in cases where the primary root DO NOT THROW the crop. syitem has been damaged by root rot. SOIL ,INTO PEANUT ROWS (see page 248) Do not cultivate beans while the

7. Unnecessary cultivation can leaves are wet since this increases harm the crop.The main the spread of foliar diseases like purpose of cultivationis to control weeds,although bacterial blight and anthracnose. it is sometimes used to break up a hard soil crust that is interfering with PEANUTS: Soil should note thrown Excessive water absorption. into 'the crop row, especially when cultivation damages. plants and roots, wastes timeand the peanut plants are young. This labor, and increases soil practice injures thi stems and compaction and loss ofhumus. buries some of the, young branches which greatly increases the plants' susceptibility to Southern stem Guidelines for rot (Sclerotium rolfs!i) and also Cultivating_ Reference Crops interferes with normal branch development. There is no need to throw soil into the row if early season weed control isadequate. "Flat" cultivation will avoid MAIZE AND SORGHUM: In many regions, throwing soil into the row. The these two crops arecommonly "hilled secret of flat cultivationis good up" during successivecultivations to early-season weed controlvto provide better drainageand to help prevent weeds in the rowfrom over- prevent lodging. Most farmers in BEANS:* Throwing soil intothe plant taking the crop. the U.S. use herbicides to provide row not onlycontrols small weeds and initial control for the first six provides better drainage(good for

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198 to eight weeks. If using tractor millet usually escapes injury since . cultivators, farmers should use it is harvested during the wet season "higOspeed"- sweeps which have a when siriga seeds are ddrmant. Maiwa low crown and do not throw as much millets, which mature later, are more soil. Wide sweeps enable the prone to attack. cultivator shanks to be kept, well Striga seeds are stimulated to away from the row since they, too, germinate by moisture and plant throw a lot of soil. juices (root excretions) from the Cultivation should cease once roots or-grass family host planes the pegs begin to elongate, around and emerge above ground in about eight weeks after plant emergence. one to two months. Flowering Cultivation at this stage can damage occurs three to four weeks later, the pegs and help spread rosette and the seeds mature in another virus, a serious problem in Africa. 30 days. A single plant can By this stage, the plants should be produce half a million seeds which big enough to provide good competition are easily spread by wind, water, with any.emerging weeds. and tools. Crops are often injured A Special Note OE Striga before the weed emerges, and severe Striga (witchweed) is a parasitic attacks cause stunting, yellowing, O annual weed which invades the roots and wilting.. of grass family plants (sorghum, maize, Striga Control Recommendations millet) and can cause losses. Hand weeding provides partial control; some herbiCides give There are several species found in good control, and one foliar Africa, India, Southeast Asia, Australia, product As been developed that can be applied with an and the Southeastern U.S. In West inexpensive water pistol. Africa, improved varieties of sorghum Hikh fertility helPs plants are sometiees heavily attacked. resist attacks, and plant breeders are working on Improved maize varieties are somewhat varietal resistance. less susceptible but native varieties An effort should be made to have better resistance. Gero type

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199 prevent movement of striga seed proper application procedUres. from infested to noninfested How Herbicides Kill Weeds fields. Some herbicides like glyphosate All crops should be kept free of grassy weeds which are hosts will kill weeds only if sprayed on for striga. their leaves. Others like simazine "Trap" crops of cereals or grasses can be planted to will not control emerged weeds,. but stimulate striga germination must be, applied to the soil itself and then plowed under before where weeds are killed as they the weeds have produced seeds. germinate by absorbing the chemical through their roots. Some herbicides like atrazine are effective either way. Guidelines for Choosing a Herbicide The Use of Herbicides in the The choice of a suitable Reference Crops herbicide depends on the type of weeds,prasent and the crop's toldance to the chemical. Weed Selectivity: Some herbicides Control grassy waedi better, some In some parts of the developing are more effective on broadleaf. 0 world, there is a critical labor types,and still others will shortage at weeding time. Herbicides' control some of each. Nearly all can be economically feasibleor herbicides are much more effective small farmers under these conditioils. on annual weeds-than perennial In Central America, herbicide uoe weeds. It is important to remember by small farmers has become cosimon in that individual herbicides seldom, many districts. Chemical we control provide a full range of weed control is a sophisticated management prIctice, and that the specific weed species however, and most farmers using must be considered when choosing a herbicides need more instruction in product t7 control it.

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200 drop Tolerance: Each crop may tolerate Glysophate is a non-selectiire contact certain herbicides, but at the same product that kills the 'green topgrowth time, be severely injured or killed of all weeds and crops. Propanil is b30 others. For example, atrazine a selective contact herbicide thatJ will kill most annual grassy and controls many grassy and broadleaf broadleaf weeds on maize, sorghum, weeds in rice without injury to and millet without injury to the the crop (it can be freely sprayed

. crop.- The herbicide 2, 4-D can also on the rice plants). be sprayed directly on maize, sorghum, Systemic herbicides are absorbed millet, and other grass family crops through the leaves (less so through to control broadleaf weeds without the roots) and then translocated injury to these crops (unless applied throughout the plant. Systematics tot, heavily or at the wrong stage of are especially usefur for killing .growth). On the other hand, glyphosate perennial weeds, although several has no selectivity and will kill all applications may be needed.Many foliage that it touches. other herbicides like atrazine have a partial systemic action. Timing and Method of Herbicide Some Important Applications Herbicide The herbicide label will state Terminology that the particular product can be applied in one or more of three ways: Pre-plant: Before the crop is planted. Most prelplant Contact herbicides kill only herbicides require incorpora- those plant parts the spray actually tion into the top 2.5-10 cm of soil with a disk harrow touches. There is little, if any,' or rototiller. translocation (movement) to other Pre-emergence: After the crop is planted, but before it or parts of the plant. Contact herbicides the weeds have emerged. Can be either selective or-non-selective._

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. Post-emergence: After the 'crop 3.75 kg/ha of Gesaprim 80 percent .and the weedshave emerged, usually.before the weeds are wettable powder would be needed to 2.5-5.0 cm tall. supply 3 kg of active ingredient per Broadcast applications are hectare (80 percent x:3 kg; x3.75 kg). applied over the entire field. Band applications are applied in a Herbicide Safety narrow strip (about 30-40 cm wide) centered over the crop row.These Fortunately, most herbicides save* the farmer money since less are relatively safe, but there are herbicide is used, but he or she will a few exceptions: still have to cultivate the

Paraquat .has an unusally high untreated inter-row area. oral toxicity and even a small How Herbicide Dosages are Given amount of diluted mixtures can be fatal. Paraquat is inactive-. Herbicide tecommendations are ted by clay or activated charco4l usually given in terms of abs.acre which should be administered orally (mixed with water) if or kg/ha of active ingredient* which oral ingestion occurs. refers to pure 100 percent chemical; Dinitrophenols (DNBP, Dinoseb, H ever, each herbicide'is usually Basanite) have high oral .toxicity_ and can also be a ilable in several different absorbed dermally (through the mutations (i,e, wettable powders, skin). ti uidS, granules) that' vary in Suspected birth defects caused by 2, 4-D type herbicides have rength. It is up to thiqormer ' been linked with faulty manu- or extension agent to figure out how facture which produces dioxins (rarely present under current much of a particular product is production methosls)t needed to satisfy the recommendation. Far these reasons, it is not Thisia much the same as figuring recommended that these herbicides fertilizer requirementSk For example be used without first receiving instructions in Dandling from a * For some herbicides the percentage of active ingredient may be knowledgeable professional.' referred to as the."acid The same general safefyluide- equivalent".

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1) 02 lines in section B. On insecticides Weed size: Post-emergence applications of manyberbicides apply to'herbicides. Except for o will not kill weeds much taller' those mentioned above, nearl -all that 2.5 cm while others will ve. effectively control larger herbicides are Class trin their weeds. relatiVe toxicity (least dangerous). Accuraci of application: Most herbicides need to be applied at fairly predise dosages. This requires calibrating the sprayer, in order to determine how much water it Factors Affecting will take to cover the field Herbicide and how much,Jterbicide'should A Performance be addedd to eache tankful. When spot.spraying, the farmer can get by using a tablespoon per gallon or cc per liter dosage, but this is the I exception. Application also Choice of product: The product needs to be uniform to avoid must be suited (0,the crop and crop injury or patches of the weed speciel Present. surviving weeds.' Soil organic matter and clay content: The rates ofmost soil-applied herbicides are very dependent on soil clay and especially organic matter content. The higher these General Guidelines levels, the higher the rate For Applying of herbicide needed. Sote Herbicides soil-applied herbicides may cause crop damage on sandy soils.

Rainfall- : Most preremergence herbicides require moderate rainfall within, a few days following application in.order to move the chemical into the READ AND UNDERSTAND THEIABEL! weed seed germination zone. Do not spray on windy days. Otherwise, a very shallow Spray drift or vapors may - cultivation may be aeeded'to damage nearby susceptible. work the chemical into the soil. crops.

193 . 20:4 Avoid spraying wnen the and most-broadleaf crops may he temperature is above 32 injured if planted within th' High temperacures increase volatility (vaporization).. period. Simazine, diuro and, and may also reduce diphInamidmay take ev- longer. herbicide effectiveness. Most others take a few, eeks to When using.wetcakle powder formulations, be sure'to a couple of months. T label agitate the sprayer should show carryover information. tank to keep- the powder in suspension.during application. Never use a herbicide on a crop for which it is,not recommended. Do not burn herbicide containers. Fumes may be released which can injure susceptible crops. Applying Herbicides with Backpack (Knapsack) Sprayers Herbicide Carryover A few herbicides do not require 6 much dosage accuracy and can be easily applied with backpack sprayers. How- Some herbicides take a long ever, most herbicides- require a level time to break down in pe soil and of precision, which is difficult to may injure succeeding crops. It it achieve With these sprayers unless likely 'sat residues may cause extra carp is taken. problems with those crops for which In order to avoid applying too the product is not recommended. much herbicide, which wastes money and Fotunately,'residues are legsof might injure the crop, or too little, a problem in the tropics where which might make the sprayinginef- higher.temperakres'favora more fective, the sprayer should be rapid breakdown of the chemicals.. calibrated (see Appendix K). Atrazine takes two to eight Once the sprayer has-been cali- months for its residues.to disappear, \ braced, the farmer mutt maintain the 4

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- A 204 I same constant spraying pressure and with only 20 liters of water per hec- walking speed that was used in the tare. The single nozzle covers a meter- calibration process. wide-swath which enables a hectare Nozzle selection is, important, to be sprayed in about eight hours Fan nozzles (see page 225) at a walking speed of 0.5 meters/. should be used to make pre-emergence second. This is a big improvement and post-emergence applications over over backpack sprayers in terms of the soil and small weeds. Cone water volume and time requirements. nozzles are best for spraying her- The controlled droplet applicator bicides on larger weeds, since they sprayer is very light and holds just provide more complete 2.5 liters of spray solution. Cali- 'fan nozzles'when used on foliage. bration is also simplified, because They should not be used for broadcast the sprayer's output is constant and applications of herbicides over the only Walking speed need be considered. soil and small weeds since the The sprayer is currently being circular spray, patterns will not manufactured by two companies: overlap properly. If two or more The "HERBIE by Micron Sprayers cone nozzles are mounted on a Ltd., Bromyard, Herfoxdshire, spray boom, overlapping spray ENGLAND HR7 4HU. This' model patterns will distort each other. uses eight flashlight batteries As for water volume, 250-300 1/ha (good for up to five hectares is adequate as long as weeds are of spraying). small or only the soil surface is being sprayed. Larger weeds The "HANDY" by Ciba-Geigy AG, require up to 500-600 1/ha when CH 4000, Basle 7, SWITZERLAND. uniform coverage is needed. The Mes five flashlight batteries. sprayer should be shaken-periodic- The price of the.controlled droplet ally to keep wettable powder applicator is about half that of a formulations in solution. backpack sprayer. However, it is Improvements in Hand Sprayers not suitable for applying most insecticides and fungicides. Low-volume hand-held sprayers: A very effective hand-carried A spray boom for backpack sprayers: sprayer that runs on flash- To reduce labor requirements for light batteries has been k4.* backpack spraying, a simple but developed by IITA. It is effective spray boom can be cons- known as a controlled droplet tructed so that two to five nozzles applicator sprayer and is can be used at once. If only two specifically designed for nozzlei are used; special "T" applying herbicides. Its extensions are commercially available special nozzle produces for -many sprayer models. Larger extremely fine droplets bOoms can be made by arranging which permit adequate nozzles along a length of narrow coverage to bec.achieved diameter pipe and connecting them

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with high-pressure plastic hose. 4. When broadcasting herbicides If an nozzles with an80° over the soil or on very small angle of spray width are used,and weeds, the sprayer boom height spaced 50 cm apart on the boom, should be adjusted to give uniform ground coverage can be three to four fingers width of achieved when the boom is carried overlap between adjacent spray (about 50 cm of the ground. (This patterns. Fan nozzles are provides three to four fingers available with different spray width of overlap between adjacent width angles such as 65°, 73°, spray patterns. As shown in the and 80°. The wider the angle, illustration, these large booms the closer to the ground the are too unwieldy to be carried boom can operate and still by the sprayer operator alone. achieve the necessary overlap. This is a big advantage on Applying Herbicides with Tractor o Boom Sprwiers windy days. Tractor boom sprayers can cover 5. Nozzles of different sizes or up to six to eight rows at once spray angles should not be used and have nozzles spaced every 40-50 on the same boom. cm. They may be used on small farms 6. The manufacturer's tables for as part of a cooperative venture. output and calibration are not Here are some guidelines: reliable. Nozzle output can be markedly affected by wear, and 1. Low sprayer pressures (30-40 lbs./ pressure gauges and tractor sq. in.) are usually recommended 4 for herbicides% Higher pressures speedometers vary in accuracy. decrease droplet size, distort 7. Wettable powder formulations need the spray pattern, and cause constant agitation to stay in drift. suspension. Mechanical or hydraulic jet agitation is a must 2. For nozzle selection follow the guidelines listed under backpack for tractor sprayers. sprayers. Brass, aluminum, and 8. The tractor must be driven at a plastic nozzle tips are cheapest. constant speed while spraying or However, they wear much faster output will be affected. A than tips made of harder metals fluctuation of only 1-2 km/hr when wettcble powders are used. can increase or decrease the dosage being applied by as much 3. If output per nozzle is too low, as one third. switch to a larger nozzle size or drive slower. Increasing 9. Tractor speed should be adjusted pressure is a poor way of to suit ground conditions. increasing spray volume. Excessive bouncing of the spray Pressure must be increased boom will cause uneven coverage. four-fold in order to double The tractor should not be driven the output. faster than 8 km/hr.

196 e 206 IIe I , w,101%- rir!..1 4.-"9..' e..

..14 , , `.// 0. 5 , 1.'/.- I 'if 4 Ili .1 . . Ir;

A boom arrangement for backpack sprayers(Courtesy of 1RKI). About 4-6 nozzles can be used when applying low water volume as with many pre- and early post-emergency herbicides.

and dosages. check herbicide selection lit. It is important to constantly for blockednozzles while spraying. RECOMMENDED HERBICIDESFOR THE REFERENCE CROPS

The number ofherbicides available for use onthe reference crops and theirindividual application guidelines aretoo numerous in.this to beadequately covered rely on manual. It is best to locally-derivedrecommendations based on fieldtrials if possible. Several resources arelisted in the bibliographythat will provide reliable generalguidelines for

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207 Sucking Insects Insect Control Aphids., leafhoppers, stinkbugs, harlequin bugs, whiteflies, and mites have piercing,. and sucking mouthparts and feed on plant sapfrom leaves, pods, and stems. Some Important They transmit a number of Facts on Insects plant diseases, especially viruses. Sucking insects do not make holes inthe leaves, but usually cause leaf yellowing, curling or crinkling.

Ingects can often beidentified by the type ofdamage they cause: Insect Life Cycles Chewing and BoringInsects A general understanding of insect life cycles is useful in Caterpillars are thelarvae identifying insect problems in They damage plants of moths. the field. Beetles and moths go leaves and by feeding on through a complete metamorphosis making holes in them orby (change in form) consisting of boring into stalks,pods, The cutworm four stages, while aphids, leaf-__ and maize ears. hoppers, whiteflies and other suck- caterpillar is unusualin ing insects go through only three' the soil that it lives in stages. and emerges atnight to cut off plant stems nearground level. (Adult stage) Settles feed on plantleaves MOTH ---,EGG and chew holes inthem. Some (Does no damage.) beetles of the weevilfamily CATERPILLAR PUPA bore into pods andseeds (Usually feeds (Dormant stage; and deposit eggsinside. on leaves.) turns into a Certain beetles canalso moth.) 'transmit bacterialand (Adult stage) viral diseases. BEETLE EGG Beetle larvae likewhite (Feeds on leaves, grubs, wireworms, androot- pods) worms live in thesoil and LARVA PUPA damage roots and theunder- (Grubs, wireworms, (Dormant stage - - ground portion ofthe_stem rootworms, etc. turns into a by chewing orboring. Feed on plant roots.) beetle.)

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208 (Adult stage) feeding or tunneling of the APHIDS, LEAFHOPPERS, underground portion of the STINKBUGS, WHITE- stem has been serious it FLIES, OTHER SUCK- -> could be due to stem ING INSECTS borers. Remember that wilting can be caused by EGG NYMPH other factors, too: dry soil, (Looks like a minia- very high temperatures, ture adult; at this root rots, bacterial and stage also sucks sap.) fungal wilts, and nematodes.

To determine if insects are the cause of wilting, dig up the affected plants. Check the root system How to Identify and underground portion Insects and 4 of the stem for insect Their Damage and disease'damage, also look for soil insects. Slit the stem lengthwise BE OBSERVANT! Troubleshooting takes with a pocket knife and practice, and a sharp eye is essen- check for borers or rotted tial. When walking through a field, tissue. closely examine the plants for Leaf curling, crinkling or insects or their damage symptoms. yellowing: Caused by sucking Check both sides of the leaves insects, especially aphids, since many insects prefer the leafhoppers, and mites. undersides of leaves. A magni- Viruses and some nutrient fying glass can be very helpful. deficiencies also produce these symptoms. Nematodes and poor drainage cause Identifying Insect Damage: Often yellowing too. it is possible to identify insects by the damage they cause. Identifying Insects: Spend time Holes in leaves: Caused by with locally experienced exten ion caterpillars, beetles, workers in the field and have them crickets, snails, and slugs. point out the prevalent crop insect (Snails and slugs are not pests (and beneficial predator insects but do attack insects) in the work area. Seek plant foliage.) out host country Dr regional insect Wilting: Usually caused by guides such as extension bulletins. soil insects like white grubs The publications listed in the bibliography are also very useful. and wireworms. If root

199

209 I hi roiol t::mar000mo Imo.% boor I.1 eel t, Major Pests of the 1 he ispeolorgr000tet1 pow i lowo of I loo. f:1:1 1 k wlo 1 It. :dull Iwo. i1 er:1d Reference Crops on the allkn and attack other-. crops :. They are MOul prva- 4 lila in LatIn Amrla. A11141.(41 p 1 :oil t tio)1 11.11 lovelorn ngonteitpovele tql" 1,4:e:iottst ol 1 o 44; 1 ow., TW:: ihtlI:4not, complete but Calmed .by root damage. Ten or deal:: with thewortpreyalui more 14r1,44 per plant or 4 rtence erop Ire::(::. hill or brown dloculoralloa al',0 percent

Partial (itte: hilly) ne lent lI. i c of the root r:yntem Indicate%

4.10iv:; Ar gIVe4 loo ArelithoNo:; nerlouN damage. Moro :Iteeille vontrol measure:: 4 Wlrmprion (1;104.0d:if): !;hiny, will he Oven. al the cud of the brown, hard larvae up Lo 1.t., - ';..) in:wet r:ectIon. Stored traln mm. 1min with :air.lege:. The larval pe:a*. :antie of which attavk the :a.ag a click heetlen attack rop:-; beloc harve:;t, will he germination need!: and below ground covered in Chapter-2 plant purl:;. 1.arval atag 14!:t%

two to ..iiic yc,ars. ie

Major Pests Of Mai".

Soil --14SoCtS ---

Whit?.. grubs (Pbvilophaga, others): ....i.e. 1 ) 1 t"..:I Brown headed, plump, six-legged, white larvae up to 25 mm long. Many are larvae of May (June) beetles and attack roots of maize and ether grass family crops, Wireworm 1..i-4 top .ind .Vill Feitttah sometime:4 causing serious damage. Especially common where maize is planted on recently cleared pasture land. Occasionally. attacks legumes. Larval stage lasts one to three years. Rootworms (Diabrotica, others): Small, slender, whitish larvae with brown heads, measuring up to almost 20 mm. They attack

200

210 Cutworms (Agrotis, Feltia, Spodoptera): These are caterpillars ranging from bright green to black.Most are rather plump and curl up when disturbed. They attack younplants and cut off stems at or slightly above the soil surface, but some will feed on the leaves. Most remain below ground during the day ittO and emerge at night to feed. . Seedrorn Maggot. A Lesser cornstalk borer (Elasmopalpus: Mature lam; 8 Adult: Caterpillars, usually light green C Injured germinating with faint stripes and distinct Ar. seed. vertical bands of brown. They are most common in Latin America. Young larvae feed first on the leaves and then bore into the stalk about 2-5cm above ground. Each builds a tunnel made of soil particles and silk that runs from the soil to the stalk hole.May also attack the root system. are larvae of night-flying moths Larval stage lasts about three that lay eggs in clusters-of 100 or weeks and pupation takes place in more on the leaves. Eggs are the soil in a silken cocoon. covered by a coating'of body hairs and scales and hitch in tiweto six Seed corn maggots (Hylemya): days in warm weather.The larvae Yellowish gray fly larvae up to are cannibalistic and attack each 6-7 mm long with a blunt rear end other until only a few are left. and a sharply-pointed head- They They then move to the leaf whorl attack germinating seeds, sometimes and feed-on the unfolding leaves, eating out the entire kernel. but may also damage the growing Maize Foliage Insects and Borers point in older plants. Larva will sometimes tunnel into older plants. Fall armyworm (Spodoptera frugi- The larval stage lasts about three perda:,Larvae have a green and to four weeks and the pupal stage brown coloring with a prominent, Only 10 days, so maize can be white, inverted "Y" mark on the attacked by several generations. head and grow to aboilt 40 mm. Damage is is easy to. spot by the ragged One of the most serious and appearance of the leaves and the prevalent maize insects in the large amount of sawdust-like excre- lowland tropics. The caterpillars ment found around the leaf whorl. Diseases and predators may greatly reduce their numbers. Liquid

201

211 1.

or granular insecticides applied W. Miscellaneous laf-feeding Caterpi- the leaf whorl are effective and llars (yellow striped armyworm, should be applied before the larvae true armyworm, measuring worm, etc.): have reached 16-18 mm. These may occasionally require foliar insecticide sprays. Corn earworm CHeliothis zea): A striped' yellow, brown or green caterpillar. The moth deposits her eggs individually on the maize silks. Eggs are white, round, and smaller than the period at the end of this sentence, but can be easily seen with a low power magnifying glass. They hatch in three to seven days, and the larvae feed on the young silks and kernels near the ear tip. Earworms seldom interfere with pollination, since most silks become pollinated the first day Corn Earworm they emerge from the ear. Eggs A Egg; B Mature larva; and C Adult. are sometimes laid on the leaves of younger plants, followed. by leaf feeding in the whorl as with the armyworm. Ear damage is rarely serious enough to justify using insecticides, which would have to be applied to the silks- Southern cornstalk borer (Diatraea), a time-consuming process. Varieties Southwestern corn borer (Zeadiatraea): with long, tight husks have good Prevalent in lowland areas of Latin resistance. America. Moth larvae are about 25- 'mm when fully grown and are white with dark spots. Eggs are laid in overlapping rows of 10-12 on the leaves near the central veins. Eggs hatch in three to six days, and young larvae spend two to three days. feeding on the leaves, making circular holes, before they bore into the stalk. Larval stake lasts several- weeks, and pupation takes "place inside the stalk. Control is Leafhopper Adult only partly successful and requires spraying the plants during.the short period before the larvae bore

202

212 into the stalks or the use of systemic insecticides, some of which are very toxic. Stalk borers (BusseolaioSesamia, Eldana, Chilo): Very common in Africa and parts of Asia and can cause serious losses. Busseola and Sesamia prefer young plants and can kill them by damaging the growing point. All four types may attack the ears on older plants in,addition to the stalks. Busseola moths mate soon after emergence from the pupal stage Aphids Wingless and and deposit their eggs in groups Winged of 30-100 on the inner leaf (USDA) sheath near the whorl. The larvae feed on the whorl and then tunnel into the young plant. Systemic insecticides applied to the soil or to the leaf whorl give fair to good control. Eradication of wild grasses that serve as borer Maize aphids (Rhopalosiphum): hosts helps reduce numbers. Small, soft-bodied, greenor blue, green insects that suck sap from Leafhoppers (Cicadulina, Dalbulus: plants and secrete a sweet Small, light-green, wedge-shaped substance (honeydew) on.which,a insects with piercing-sucking black mold grows. They can stunt mouthparts. Cicadulina transmits and deform the tassels, causing maize streak virus in Africa, poor. pollination. Treatment should and Dalbulus spreads corn stunt be considered if 50 percent of the virus ( "achaparramiento ") in plants have some aphids and 10-15 Latin America. Both diseases percent are heavily infested. Insec- can cause serious losses. Systemic insecticides give long:-- ticides are effective. 'term control.

Grasshoppers: Cause serious ------____._._ losses in parts of Africa. Foliar sprays and baits are effective unless the infestation is severe.

203

213 Common Storage only the surface layer of stored, insects of threshed grain with an approved Cereal Grains insecticide like Malathion or pyrethrin.

Maize weevil (Sitoohilus zeamais), rice weevil (S. orvzaq), and granary weevil (. granarius): All have Major Sorghum Pests long snouts and are about 8.3mm long. Only the maise and rice weevils can fly and infest crops in the field. Females live several Sorghum is attacked by many of months and lay 200-400 eggs by the same insects that attack maize, boring holes in the kernels and but two other insects can also depositing the eggs inside. The cause serious damage. white, legless larvae feed'on the inside of the kernels, then pupate, stfiseggSorhuimientariniasorhiola: and finally emerge as weevils. A small orange fly about?-12 . All three species are more common This is the most important sorghum in humid than dry regions. pest world-wide. The adult lives only about a day and lays eggs on Angoumis grain moth (Sitotroga sorghum grain heads during flower- cerealella): A small cream- or tan- ing. Larvae hatch in two to four colored moth with a wingspan of days and spend 9-11 days feeding on about 12.7 mm that is often the the juices of the developing seeds, major stored grain pest in drier preventing them from developing. regions. Adult moths have a black fringe on the tip of each forewing. The pupal stage lasts two to six days for a total life cycle of just They can infest grain both in the 15-20 days. field and during storage, but can penetrate only about the top 4-inch Some local varieties show fair layer in stored, threshed grain. resistance to this pest. Sorghum Maize stored as ears can be heads can be sprayed with an insec- completely infested, however,. Each ticide three to five days after female lays about 40-400 eggs on they emerge from the boot. Sorghum the outside of the kernels, and should not be planted near young the tiny larvae burrow inside to sorghum or Johnsongrass, and out of feed. Pupation takes place inside season sorghum heads should be the kernel, and the young moths removed from fields. In cooler emerge to begin a new cycle. The areas, the larvae pupate in a mths-themselves do no feeding. silken cocoon, but may also do this Unlike most other storage-Insects, in very hot, dry weather. Plowing. the angoumis grain moth can be .under residues may help control the controlled by spraying or dusting pest in these cases.

204

214 ,

. a

7-- ---

e /

, I - -

The sorg1-..:.:a midge, Contatinta sorghiapla (Coq.). Adult o female and larva in its cocoon.

205

2J damaged main

Maize Weevil (Sitophilits L zeamais). The rice weevil (S. oryzae) looks tia identical.

part of damaged cob

, Sorghum shoot fly (Atherigona Millet Pests soccata).: A major pest in Africa and Asia. Adults look like small houseflies and lay-eggs on the leaves of young plants. Larvae move down into the leaf whorl aed then bore into the young stem, ' Millet is attacked by many of often killing therowing point. the same inects as sorghum, includ- The youngest leaf then turns brown ing the shoot fly, midge, and stem and withers-this condition is borer, but damage is usually less called "deadheart". Some sorghum ':serious. The millet grain midge varieties show shoot fly resistance. (Garda pennisetti) is common in Insecticides applied to the whorl the savanna,region of Africa.A are not as effective as pre-plant caterpillar (Masalia spp.) has applications of systemic insecticides increased in numbers in the northern to the soil. savanna and Sahel during the 1970's and can cause serious head damage.

0 206 t

216 damage increases the likelihood of aflatoxin ( a harmful toxin and carcinogen produced by Aspergillus fungus; see section on diseases). Thrips: These tiny (l mm) yellow Sorghum to black insects have two sets of Shoot fragile wings which are fringed Fly. with hairs along the rear edge. Immature thrips (nymphs) are light yellow to orange and.smiller than the adults. If disturbed, thrips will jump or hop.They can cause. serious damage by feeding in t1e buds'or folded leaflets. They have rasping-sucking mouthparts which cause the leaves to be scarre and distorted as they tinfold. Thrips can also spredd spotted wilt virus.

adult 9

Peanut Pests

White grubs, wireworms, and rootworms attack peanut roots, and the latter two also attack the pods. Termites can severely attack the pods, but.damage is usually patchy. Treating planting seed with an insecticde, destroying the nests with Chlordane or other insecticides, or applying insecticides broadcast or banded along the crop' row are effective on termites. The lesser cornstalk borer may bore into stems and pods. In Senegal, about a dozen types of millipedes damage pods. Any pod The flower thrips. Frankliniella triad

207 217- ,/

Leafhappers: Can be another majdl. Con'earw9rms (Heliothis spO.), pest. Adults are around 3 mm longt armyworms (SpodopteiS, Pseuda- Vaic green, and wedge-shaped. Inv-, etia), andother caterpillars maitre leafhoppers (nymphs) are feed on the leaves. Blister similar in appearance to ,adults, beetles lEpicauta spp.) are but smaller and without wings. brightly colored with alternate Both stages have piercing-sucking bands of black and red or yellow- mouthparts. The first signs of they feed on the flowers.. leafhopper damage are yellow "Ii4 Aphids occasionally attack peanuts. formations ut the leaf trips, mid One specieslApHis croccivora) severe ...cases can cause stunting spreads rosette virus, a 'serious and leaf drop.. probiem in Africa.' Spider mites (Tetranychus and Peenuts are very susceptible other species; ,Common in hot, to attack by storage insects! dry conditions. They are sucking The groundnut bruchid (Caryedon

insects, and- feeding damage may spp.) is 'a serious pest in West appear ag translucent dots on the_ Africa. Thin weevil lays eggs on leaves. Some insecticides will the pods after the crop has been not control Mites, while Kelthane lifted from the ground, and the is effective only against mites.- larvae tunnel into the pods and kernels.

Bean Pests r The f011owing information is based on The International. Center for Tropical Agriculture (CIAT) studies on the major insect pests of commonbeans (Phaselous vulgaris) in Latin America. Seedling Stage Insects Cutworms and white grubs may cut off the stems of young seedlings. White grubs area usually only serious A Spider Mite 40nr.0fetnamia, when beans tare planted following pasture. The lesser cornstalk borer may bore into the stem just below the soil surface and move upwards and kill the plant. Clean fallowing for long periods or heavy flooding will control these borers as will

208 218 r.,

.1.. granular-. insecticides applied near Caterpillars usually do not cause the aped row at planting. economic damage on bean leaves. The bean leafroller (Urbanus or Eudamus), Leaf Feeding Insects' saltmarsh or wooly bear caterpillar Many species of beetles, such (Estigmene), and Aedylepta caterpillar -as die banded cucumber beetle are the most common. (Aiabrotica balteata), bean lei Sucking Insects beetle (Cerptoma), flea beetle .(Epitrix), and Mexican bean beetle The leafhopper species Empoasca (Epilachna), attack bean leaves. Kraemeri is the most serious insect The most serious damage is caused pest of beans in Latin America and 'during seedling stage when the is also found in other regions. insec%can defoliate,the plant It does not transmit viris:(some more dily, or during flowering. other leafhoppers do) but causes larvae and adults of the severe stunting, yellowing, and 'MexicanMexican bean beetle feedon the leaf curling. Work done by CIAT leaves. The larvae of the other has shown that yields are reduced beetles feed mainly on the roots about six percent for each leaf- *.of beans, maize, and certain weeds. hopperpresent per leaf. Eggs hatch in eight to nine days and the nymphs, feed on the plants for eight to eleven days before becoming adults. The adult stage 0 lasts about 60 days and is more damaging. Beans grown with maize are less affected than pure stands. Mulchingoreduces leafhopper popu- latiois. Leafhopper problems are generally more aevere in hot, dry weather. Several species of aphids attack beans, although their feeding causes little direct damage, they can transmit bean common mosaic virus. Mexican Bean Beetle Adult and Larva- .Several species of mites attack -beans. The red spider mite is found on the lower leaf surface, and heavy'

0 infe-stations turn the-leaves brown. The tarsonamid mite is too tiny to be seen without a magnifying glass, but causes young leaves to'curl up-

209 219 ward. Mites are seldom. serious Adult weevils are short-lived except during the dry season. and do little feeding.. Both types'of weevils may be present Whiteflies (Bemisia syp.) do not usually cause direct damage initially, but A. obtectus is a but can transmit bean golden' better competitor at lower temperatures and will eventually mosaic virus and bean chlorotic predominate under these conditions. . mottle virus. They are Often controlled by natural predators, These bruchid weevils are estimated to cause storage losses of up to and most insecticides are effective. 35 percent in Mexico and Central Pod Borers America. The bean pod weevil (Apion Slugs occasionally cause Serious godmani) is a serious problem in leaf damage and are mainly active Central America. Adults are black at night or on wet, cloudy days.' and about 3 mm long and they feed Damage is msot likely along field on flowers and pods without causing borders but may move inward. much damage. However, the female Cleaning the field of weeds and chews a small hole in young pods plant debris helps control them, and deposits an egg. The larva but baits are the most effective 'feeds on the inner pod and the means of control. Slime trails developing seeds. Pupation takes on the leaves indicate the presence place in the pods, and the adults of slugs. emerge near harvest time. Bean types vary in their resistance. A number of insecticides give good control if applied once at a Cowpea Pests week past flower initiation and again a week rater. Carbofuran applied at planting gives excellent control. The caterpillar Maruca testu- Bean bruchids (Acanthosce- lalis is the major cowpea pest in lides obtectus and Zabrotes the Savanna region of Africa. It subfasciatus) are snout less attacks flowers, pods, and leaves, weevils about 2. 5mm long and are causing yield losses up to 70-80 the major storage pests of beans. percent. A. obtectus predominates in cooler areas, while Z. subfasciatus Coreid bugs (plant bugs) are prefers warmer regions. Life larger sucking insects that feed cycles for both are very similar on green pods and cause them to with eggs being laid on stored shrivel and dry prematurely. beans or in cracks of growing pods in the field. The larvae tunnel into the seeds to feed.

210

:1 ' 220 The leaf feeding beetle Ootheca IITA, in Nigeria, estimates that mutabilis can cause yield reductions one-third of the cowpea crop in when young plants are heavily Africa is destroyed by bruchids. attacked. It also carries yellow mosaic virus. The flower thri (Megalurothrips s]ostedti) is a major cowpea pest in tropical Africa. Thrips have sucking-rasping mouthparts and are very small (about 1 mm or less). Methods of The snoutless bruchid weevils Insect Control (Callosobruchusspp) infest cowpeas both in the field and in storage. The adults can fly up to a kilometer and are most likely to infest crops downwind from strong facilit- Non-Chemical Methods ies. The 2.5 mm adults lay eggs on the pods or seeds, and the larvae bore into the grain.

Many natural controls act to keep insects in balance.. Weathei factors like temperature and rainfall can restrict the distribution of an insect species. For example, mites' and leafhoppers are usually more prevalent under dry 2mm 0 conditions. 9 C. chineruit Geographic barriers like large bodies of water, mountains,

-1s4r-.1. --, kael.0-"' :.:0 .;451iii .6:P damaged and deserts can also limit 414.III.11..ntaite insect distribution. C4;t.-.; 1.--1-1 Frogs, toads, lizards, moles, 0 2 cm , i, and birds are some of the many t,\*..i ?--- ) . 1 .01.1s . animals that feed largely on N.j insects.

L. 1., _J.-1 Beneficial predator insects .ao 11 : vill like ladybugs feed on aphids, conhomm,, while others like the braconid,

Cowpea bruchids (Callosobruchus ERE.) . wasp and tachnid fly lay eggs

211 221 VA

on or in certain pests which are controlled by this method in killed by the developing larvae. various parts of the world. Some predator insects like the praying mantis eat beneficial Microbial insecticides such as insects as well, however. Bacillus thuringiensis (effective Insects are also attacked by against a few types of caterpillars) viruses, fungi, and bacteria which help keep populations down. are now commonly used By farmers As agricultural activities have and gardeners in many areas. increased, many of these natural Unfortunately, biological control balances have been upset and can no measures are presently effective longer be relied upon to keep against a very small portion of harmful insects under control. harmful insect speciei. Monoculture and the existence of Cultural controls vast areas under cropping have Cultural controls such as crop led to marked increases in a rotation, intercropping, burying number of insect pests. Indiscri- crop residues, timing the crop minate use, of pesticides has calendar to avoid certain insects,

actually resulted in buildup of and controlling weeds and natural . harmful insects in some cases. vegetation that harbor insects are Many of the traditional crop all effective control methods for varieties, despite their lower some insects. In most cases, productivity, have better insect however,,cultural controls need resistance than some of the to be supplemented by other methods. improved varieties. Varietal Resistance Biological Control Crop varieties differ consi- Biological control is the derably in their resistance. to purposeful introduction of preda- certain insects. For example,

1 tors, parasites or diseases to maize varieV.es with long, tight combat a harmful insect species. husks show good resistance to ear- About 120 different insects have worms and weevils. Researchers at been partially or completely CIAT have found that some bean,

212 . . 222 varieties are relatively unaffected Chemical Control by leafhopper damage during the wet season, while others suffer yield losses of up to 40 percent. Screening for insect resistance is an important part of crop Chemical control refers tothe breeding programs. use of commercial insecticides in "Organic" Controls the form of sprays,-dusts, granules, "Organic" control refers to baits, fumigants, and seed treatments. non-chemical methods in general. While some of these insecticides like These include the application of rotenoneand pyrethrin, are natur- homemade,"natural" sprays made ally derived, most are synthetic from garlic, pepper, onions, soap, organic compounds that have been salt, etc., and the use of developed through research.' materials like beer to kill slugs Advantages of Insecticides: and wood ashes to deter cutworms . They act rapidly. and other insects. Some of They are the only practical means of control once an these "alternative" insecticides insect population reaches are slightly to fairly effective the economic threshold of damage on a commercial-size on small areas like home gardens plot. and where insect populations are They are available with a relatively low. They are seldom wide range of properties, feasible or effective on larger ,species effectiveness, and application methods. plots, especially under tropical They are relatively inexpen- conditions that fav6r insect sive, and their proper-usage:- buildup. can often return $4.00 -5.00-% for every $1.00 spent.

it' 213 223. Disadvantages of Insecticides: Immediate toxicity: Some insecticides are extremely toxic in insect resistance to small amounts to humans and pesticides: This is a growing animals. Again, it is important problem. By 1961, 60-70 to realize that insecticides species had developed resis- vary greatly in their toxicity. tance to certain products, and the number had increased Current Status of Insecticide Use to around 200 by the mid- in the Reference Crops 1970fs. At the present time and for the Outbreaks of secondary pests: Wined/ate future, insecticide usage Few insecticides kill all will often be an essential part of types of insects, and some actually promote the increase any package of improved practices of certain pests. For for the reference crops. For this example, continual use of Sevin (carbaryl) in the same reason, all extension workers must field may increase problems learn the basic principles of safe with some types of aphids which it does not control, well. and effective insecticide applica-

CDamnge-to'non-target-species: tion-. Some-extentionworkers-may-.... These include beneficial be personally opposed to the use predators such as bees and wildlife. of these chemicals, but it is a Residue hazards: Some chlori- fact that farmers throughout the nated hydrocarbon compounds developing world are using them, like DDT, Aidrin, Endrin, Dieldrin, and Heptachlor are often in an unSafe.and indiscrimi- highly persistent in the nate manner due to the lack of environment and may accumulate in the fatty tissues of wild- proper instruction. Most developing life, livestock, and humans. countries have few, if any, pesticide Many other insecticides are broken down into harmless regulations or restrictions on en- compounds fairly rapidly. . vironmentally harmful products like Aldrin or highly toxic ones like Parathion. By instructing farmers in safety precautions and in the appropriate choice and use of insec-

214 224 ticides, the incidence of human and number of insects and their density and population' poisoning and possible environmen- counts-is.an essential part tal damage can be greatly reduced. of this system. The advent of integrated pest Integrated Pest Control control dates back to the early 1970's, and Wit of the efforts The disadvantages-of total have been directed at cotton where reliance on insecticides have insecticides frequently account for given rise to integrated pest up to 80 percent of total produc- control or pest management which tion costs. Some remarkable involves the judicious use of successes have been achieved with these chemicals based on the other crops as well. For the following guidelines and principles: ' reference crops, integrated pest o The development and use of control is still in the very cultural and other non-Chemaz-- early stage, especially in develop- - cal control methods to avoid or red4ce insect problems. ing countries. o Determining crop tolerance USING INSECTICIDES SAFELY to pest damage based on the principle that complete Insecticide safety guidelines, freedom from pests is seldom toxicity data, and first aid measures necessary for high yields. Nearly all plants can toler- are covered in Appendix 3, which ate a surprising amount of, should be referred to before working leaf loss before yields are with insecticides. seriously affected. o The appropriate timing_ and frequency of treatments to replace routine, preventative spraying. Treatments are not initiated before the particular insect has reached the economic damage threshold, which will vary oonsiderably with the species. Insect scouting- looking for related kinds

215 225 sects by being absorbed through Some Important their bodies. Contact poisons act Facts on as stomach poisons if eaten by Insecticides insects. Most insecticides are non- systemic and are not absorbed into the plant. Systemic insecticides Pesticide Terminology are absorbed into the plant sap, and most are translocated through- Pesticide: A general term referring out the plant. Most systemic to chemicals that control crop insecticides like Metasystox, insects, mites, weeds, diseases, nematodes and rats. Dimethoate (Bogor, Perfecthior), Miticide (acaricide): A pesticide and Lannate are sprayed on plant Mites are that kills mites. foliage. Others like carbofuran, related to spiders and not all insecticides will kill them. Thimet, and Di-syston, are applied Some pesticides like Keithane to the soil in a band along the control only mites, while others likp ni zin n nd Malathion kill crop row, where they are absorbed mites and other insects. by the plant roots and then trans- Nematocide: A pesticide that kills located to the stems and leaves. nematodes. A few insecticides like carbofuran and Mocap will also Some of these soil-applied systemics control nematodes, but most will will also control certain soil not. Someneriatocides like Nemegon control only nematodes, insects. while others like VAPAM, Basamid, There are several consideriions and methyl bromide are general soil sterilants that kill insects, in choosing between a systemic and weeds, fungus, and bacteria as well. non-systemic insecticide:

Systemic vs. Non-Systemic Insecticides

Systemic insecticides are especially effective against Nearly all modern insecticides sucking insects like aphids, are contact poisons that kill in- leafhoppers, stinkbt4, and

216 thrips since these feed on non-systemiLs like Parathion the plant sap. However, and Endrin. (See Appendix J.) many non-systemic contact insecticides will also control sucking insects Types of Pesticide adequately. Formulations / Most systemics 'are less , ,/ f effective against caterpillars Most insecticides are V and beetles, but may give good control of some stem available in several types of borers. formulations: Foliar-applied systemics WETTABLE POWDERS, SOLUBLE *may remain in the plant POWDERS: These range in For up to three weeks. strength from 25-95 percent Soil-applied systemics activeingredient and c*re may providel control for ::obe diluted with up to six weeks. However, water and applled with a this also means that they rksE must not be applied close SO W is a wettable powder enough to harvest time to containing 50 percent pure cause residue problems. carbaryl by weight. Once mixed with water, wettable Most systemics will not harm powders require periodic beneficial insects. agitation (shaking or stirring Foliar-applied systemics to keep them from settling are not broken down by to the bottom. Soluble sunlight or washed off the powders ("SP") are completely leaves by rainfall as with soluble and do not require non-systemics. agitation. Since they are translocated, EMULSIFIABLE CONCENTRATES systemics do not reguire ("EC" or "E"): these are uniform spray coverage when high strength liquid formu- they are applied to the leaves. lations. Like wettable New 'growth occuring after powders, EC's are meant to application is also protec- be diluted with water and ted. applied with a sprayer. They contain 20 -75 percent Some systemics like Thimet, active .ingredient: In Di-syston, and Systox are countries using pounds and highly toxic both orally, gallons, a label that reads and dermally. However, the "Malathion S E" would refer same is also true with some to a liquid formulation of

217 227 malathion that contains 5 lbs. They are especially well active ingredient per gallon. suited for soil applications Where liters and grams ire and for.placement in the used, EC's are often labeled leaf whorls of maize and in terms of grams of active sorghum to control armyworms. ingredient per liter. For Granules cannot be effectively example, Tamaron 600 is a applied to leaves, because liquid formulation of Tamaron they roll of Furadan 3G is containing 600 grams of active a granular formulation that ingredient per liter. contains 3 percent pure o DUSTS ("D"): Unlike WP's and carbofuran. EC's, dusts are low strength o FUMIGANTS: These are available formulations (1-5 percent as pelletal granules, liquids, active ingredient) and are and gasses whose fumes kill meant to be applied without pests. They are used to kill dilution by a duster. Dusts insects in store4 grain or are usually more expensive applied to the soil to kill, than WP's or EC's due to Jr:elects, nematodes, and other higher transport costs per pe: ;ts. unit of active ingredient: However, if dusts are blended' o BAITS: These are usually the within the country, they may mast effective formulations be competitive cost-wise and for controlling cutworms, are especially suited to crickets, slugs, and snails. situations where a farmer Cutworms are most effectively has difficulty transporting controlled with baits rather water to his field. They do than with sprays. Baits should not stick to the leaves as be scattered near the plants well as sprays and are more in the late afternoon if rain- easily washed off by rainfall. fall is unlikely. Bait should Retention is improved if they not be left in clumps which are applied while the leaves might poison birds or livestock. have dew on them. Dusts pose One kg of bait should cover more of an inhalation hazard about 400 sq. meters. than sprays. They should never be mixed with water. Cutworm bait recipe: o GRANULES "(G"): Like dusts, 25 kg of carrier (sawdust, granules are low-strength rice' bran, maize formulations meant to be flour, etc.). applied without dilution. 3 1 of molasges

218 228 1.25 kg active ingredient Chlorinated hydrocarbons of trichlorfon or (organochlorines): Many of carbaryl the insecticides in this Water can be added to group such as DDT, Aldrin, moisten the bait. Endrin, and Dieldrin have Slugs and snails can be con- very long residual lives and trolled by applying baits in have caused environmental the late afternoon ine band problems such as fish kills. along the field's borders or However, other members such within problem areas. It as Methoxychlor are readily should not be applied if biodegradable. Toxicity rain is expected that night, to humans and animals varies since rain may (bash the greatly, within this group insecticide from the bait. (see Appendix K). Slug and snail belt recipe: Organic Phospates (organophos- 25 kg maize flour or bran phates): The insecticides of 10 1 molasses this,group such as Malathion, 65 g metaldehyde (a stomach Dipterex, Diazinon, and Para- poison of low-dermal thion have a much shorter toxicity) residual fife than most of or 0.5 kg active ingre- the organochlorines. Their dient trichlorofon toxicity to animals and humans or 0.5 kg active ingre- varies mreatly. Some like dient carbaryl Parathidn, TEPP, Endrin, and Thimet are highly dangerous, while others like Malathion, Gardona, and Actellic are among the safest insecticides available. Chemical Classes Carbamates: Relatively few Of Insecticides insecticides belong to this group and they tend to be of moderate to low toxicity. The exceptions are carbouran and methomyl which have very high oral toxicities. Carbaryl Commercial insecticices fall and propoxur are probably the best-known carbamates. The into three main chemical classes residual life of this group or groups: varies from short to moderate.

219 229 Insecticide Dosage Calculations

For all types of pesticides, -----17-AMOUNT-Ole-ACTIVE INGREDIENT there are four basic ways of NEEDED PER HECTARE: F6t------_. ?4( example, a dosage might be given stating dosages: as 2 kg active ingredient carbaryl per hectare. This , 1. Amount of active ingredient (pure chemical) \ means 2kg of pure (100%) Sevin. needed per hectare or acre. Since actual pesticide formulations vary in strength 2. Amount of actual formula- from 1 percent up to 95 percent, tion (i.e. Sevin 50 WP orit takes some Math to figure or Faradan 3 G, etc.) out how much of a given formu- needed per hectare or lation is needed to supply a -' acre. given amoxint of active ingre- 3. Amount of actual formula- dient. If the local agricul- tion needed per liter or tural'supply store sells gallon of water. .carbaryl 50 percent WP, the farmer would need 4 kg for each 4. As a percentage concen- hectare in order to supply 2 kg tration in the spray active ingredient. water. Note that nothing' is said about Types 1 and 2 dosages are how much water the farmer should mix .with the pesticide when .suited more to large plots or to he sprays it on the plants. those pesticides (especially This will depend on plant size, plant density, and the degree herbicides) needing very of coverage desired. The only accurate dosage application. way to find out how much water is ne ded is to calibrate the Sprayer calibration is needed in sprayer.

both cases to determine how much 2. AMOUNT OF ACTUAL FORMULATION water to use andhow much NEEDED PER HECTARE OR ACRE: ' pesticide to add to each tankful. A recommendation calling for 4 1 of Malathion 50 percent per Types 3 and 4 are very general hectare, for example, is recommendations best suited to somewhat simpler than Type 1 since it is given in terms of smaller plots or where dosage actual formulation rather than accuracy is not critical. active ingredient. However, the farmer still needs6to know how much formulation he,needs for his field's area and how much water it will take to provide

220 23 0 A° 1

adequate coverage with his Type 3 recommendations, no -- _sprayer. This requires sprayer sprayer calibration is needed, calibration;------and dosage accuracy is not as good ai-laith Types 1 and 2. 3. AMOUNT OF ACTUAL FORMULATION NEEDED PER LITER OR GALLON OF$ WATER: If the recommendation is expressed as ,for example, 5 cc of Malathion 50 percent .PesticideMath EC per 1 of water, no sprayer . calibration or dosage calculation Converting recommendations from an is, needed.' The drawback is that active ingredient basis to an actual the amount of pesticide the formulation basis, farmer actually applies on his field depends entirely on how fast he or she walks while spraying, how coarse or fine the spray is, and 0 how much pressure is used. Once you know how much actual However, if proper guidelines' formulation is needed per hectare are followed, Type 3 recommen- or acre, you can easily calculate dations are-precise enough how much is needed for farmers' for most conditions and are fields by multiplying the field the most feasible for small size in hectares times the dosage farmers. They should not be per hectare. used for most herbicides Following a p4rcentage strength where accuracy of dosage is spray recommendation: critical. Determine first whether the 4. AS A PERCENTAGE CONCENTRATION spray's perCentage strength is IN 'ME SPRAY WATER: This is to be calculated in terms of active basically the same as Type 3, ingredient or in' terms of actual except that ;the concentration formulation. For example, one of pesticide 'in the spray water recommendation might be expressed is given in terms of percent as 2 percent Strength spray in rather than cc/liter. Such terms of pure Malathion. recommendations are usually based on percentage by weight, Another recommendation might althodgh sometimes a volume call for using a 0.1 percent strength spray of Lebaycid 50 basis is used when dealing with SEC's (the actual differ- percent EC for controlling thrips ences are slight). The per- on peanuts. centage figure given may refer to active ingredient ow to actual formulation. As with

221 231 4,1 For wettable powders f. When using Ws, a percentage Guidelines strength spray is based on weight of pesticide to weight Mr Applying of water. Since. 1 liter of water weighs 1 kg, these Insecticides formulas can be used: Active ingredient basis . Grams of wettable powder needed 'per liter of water 2% x 1000 20 When is Treatment SOg 40% Necessary? Actual product ba2is Grams of wettable powder needed per liter of water Farmers should apply insect- = % strength spray deV.red x 1000 icides in respOnse to actual For liquidi (EC's) insect problems rather than'on Active ingredient basis, a routine andindiscriminate cc (ml) of EC needed per liter of water "basis. Ideally, insecticides % strength spray desired-x 1000 should be used only when. damage % active ingredients in the EC has reached theeconomia.threshold. This level varies with theinsect species., the crop, and the typeand extent of'damage.

4 General guidelines (see also the unit on major reference crop insects);

ea. Soil insects. These pests . should be treated preventatively by making pre-planting or atplanting insecticide applications if a known problem exists. Treatments after planting are generally not effective except -AM in .the case of cutworm baits.

222

232 J (27

Leaf-eating insects (beetles, Using a Sprayer caterpillars): Crops can Effectively tolerate considerable defoliation as long as new leaves are being continually produced. Loss of leaf area becomes more serious as the vegetative Achieving the Correct Coverage stage nears its end, although The extent and uniformity defoliation in the very late of coverage needed depend on the stages of grain development tstscieinsects' tocion:rin:thl: or will not have a big effect on yield. being used. In some cases such Stem-borers usually cause more as armyvior's feeding in the serious damage at much lower' maize leaf whorl, the insectis populations than most leaf-, very localized, so general eating insects. The sorghum coverage is not needed. Other shoot fly, sorghum midge, and insects are more general feeders one species of bean leafhopper and require thorough spray (Empoasca kraemeri) are other coverage over the whole plant. examples of insects that reach Since they are.translocated, the economic threshold of damage systemic insecticides do not at relatively low populations. require the uniform coverage non-systeOcs do. Sucking insects: Not all species of aphids and leafhoppers spread The amount of water need for virus diseases. For example, adequate coverage varies with CIAT found that bean yields plant size, density, type of were reduced about 6 percent product (systemics versus non- for each Empoasca kraemeri systemic), and insect location, leafhopper present per leaf, but there are some rough guide- even though this species lines: does not transmit any viruses. Water rates for insecticides: Bean plants can tolerate aphids / When covering the entire well unless they are of a / foliage.of full size plants, species capable of transmitting at least 500-550 1 of water common bean mosaic virus. per hectare will be needed when using conventional sprayers. When spraying is localized or plants are very small, water volume may be only one-quarter of this amount. I Too much spray is being applied if there is a visible amount of runoff from the leaves,

/ 223 233 Commercial stickers and caused althougn this canalso be spreaders are relativelycheap. by not usingenoughwettingagent However., if notavailable commer- be'made at home. (spreader). cially, they can Egg white, cassava(yuca, manioc) flour, and corn starch canbe used as stickers atabout 15 cc per 15 liters. Liquid dishwashing Using aSpreader detergent makes asatisfactory And Sticker spreader at about the samerate. Non-ionic spreaders: Paraquat and diquat post - emergenceherbicides require /"" are unusualin that they A spreader(wetting agent) non-ionic spread- of the use of special surface tension avoid deactivation reduces the them to ers in order to spraydroplets, allowing (loss of effectiveness). Ortho-7.7 spread out ratherthan remaining available non- on theleaf is one commonly asindividual globules ionic spreader. Spreadersmarkedly surface. spray improve theuniformity of coverage andalso help prevent rolling off the droplets from leaves. (adherent) is aglue- A sticker that helpsthe spray like substance and stick totheeaf surface washed off byrainfall resist being orsprinklerirrigation. stickers and Choosing a Many commercial including Spray Nozzle spreaders areavailable, combinationsticker-spreaders. label willindicate The pesticide sticker is if a spreaderor a If sprayingthe soil, needed. sticker neither aspreader nor a When sprayingthe leaf is needed. spreader is not whorl of maize, a available in sticker mightbe Spray nozzles are needed, though a differing in output, sticker and a wide variety helpful. Use of a of spray patternangle, and type spreader isespecially' important fungi- spray pattern.Proper nozzle when applyingmost foliar cides.

224

4. 234 1.

-. ,YzA10110 e4I4t4,:kaig:01;$;&:

flat fan flat even solid cone hollow cone

Spray Patterns

selection has an important IinfluenCe on pesticide effectiveness. Type of Spray-Pattern: Care should Nozzle Output: Many backpack,(knap-: be taken to choose the right spray sack) prayers come equipped with pattern for the job. adjustable nozzles which allow the farmer to vary the output by making Flat (Fan) Spray Nozzles are the spray finer or coarser. This ideal for making broadcast would seem to be an advantage, (full coverage) applications' buth such nozzles usually do not of insecticides or herbicides maintain their setting well and over the soil surface (and' output can change considerably small weeds). The application during application. This is unsa- rate decreases at both edges, tisfactory where accurate dosages so the spray patterns of ad- are necessary, and it makes sprayer jacent nozzles should be over- calibration difficult. Fixed lapped about three to four orifice nozzles are available in a fingers width at the soil wide range of outputs and should surface to achieve even be used whenever possible. distribution. Fan nozzles do not provide as good a coverage Spray Pattern Angle: See flat spray as cone nozzles when used to

225 235 VIEW LOOKING DOWN

IMO OF TRAVEL

f Angle nozzles forward in line of travel so thatspray rolls down the row, not across it.

Illustration courtesy of Rohm & Haas Co., Phila- delphia, Pennsylvania

Ideal tractor spray boom arrangement for applying insecticides and fungicides and achieving uniform coverage. Note that the drop nozzles are angled'about 30° upward as well as 30° forward. Only one tier of "drop" nozzles may be needed on small- to medium-size crop plants.

226

236 spray crop foliage. Fan Nozzle Screens: Nozzles used on nozzles are available in tractor boom sprayers usually have several different angles mesh or slotted strainers to help of spray width. Wider prevent clogging. Some backpack angles allow the spray boom sprayers have strainers or can to be carried closer to the have them added on. Routine ground and this lessens spray cleaning is required, especially drift problems on windy days. when wettable powders are used. Even Flat (Fan) Spray Nozzles Tips on Using Backpack Sprayers to should be used for making band Apply Insecticides applications of pesticides to the soil. Spray output does Use good pressure and a fine not decrease at the edges, spray. Pressure is too high so spray patterns should not if excessive spray drift be overlapped and used for (misting) occurs. broadcast applications., Maintain a steady pace through Solid Cone Spray Nozzles the field." Avoid pausing at provide better coverage of each plant .unless the crop is plant foliage than fan very large. nozzles but should not be Rotate your wrist while spray- used to apply herbicides ing so that the spray hits and insecticides to the soil. the foliage from different Hollow Cone Spray Nozzles angles. offer somewhat better foliar Keep the nozzle far enough coverage than solid cone away from the foliage so . nozzles due to,greater leaf that the spray has a chance agitation as the spray to spread -out before hitting pattern passes over the plants. the leaves. Whirlchamber (nonclog) Spray If using a wettable powder', Nozzles are special wide remember to periodically angle hollow cone nozzles shake the sprayer to keep that can be used in place of the pesticide in solution. fan nozzles. Their design reduces clogging, and drift Keep a piece of soft wire is minimized because of the handy for cleaning out clogged wide angle pattern (enabling nozzles, but use it gently lower boom height) and larger to avoid damaging the nozzle droplet size. opening.' Do not spray plants when their leaves are wet or when rain is likely within a few hours afterwards.

227

237 Do not add wettable powders or Sorghum: Trichlorfon causes severe EC's directly to the sprayer injury. Azodin and tank. First mix them thorough- methyl parathion cause ly in a bucket with several some injury. liters of water. Make sure wettable powders are completely Peanuts:Minor foliar injury which dissolved. shows up as reddish brown spots on the earliest leaves is sometimes caused by soil applications of Pesticide carbofuran, Thimet, and Compatibility Disyston. The plants usually outgrow the damage with no yield reduction. Runner Most pesticides are compatible varieties on sandy soils with each other in the spray tank, are the most sensitive, but check the fable to make sure. and dosage should be In some crops like peanuts and reduced by 25 percent vegetables, foliarinsecticides under these conditions. and fungicides are often applied together. Spray compatibility charts are available from many pesticide companies. Water with a pH of 8.0 or above (alkaline) Causes a rapid breakdown of organic phosphate Insecticide Recommendations insecticides. Such high pH water For the Reference Crops is usually confined to limestone or low rainfall areas. Special buffering agents are available to lower the pH if necessary. Certain insecticides are phytotoxic (injurious) to certain Particular pesticides are not crops. Always check the label recommended for the reference crops instructions. Wettable powder in this manual because of the poten- formulations tend to be less tial misclassification of pest phytotoxic than emulsifiable problems and misused s_icides. concentrates, especially in Rather than rely on manual for temperatures over 320C. pest diagnosis and p._,.,cide selection, it is recommended that you rely on the insecticide recommenda-

228

VW 238 tions of your country's extension Excesses,deficiencies or service if they are known to be imbalances of soil nutrients effective and if they do not involve the use of high-toxicity Class 1 Excessive soil acidity or chemicals (see Appendix K). Before alkalinity using any insecticide, refer to the Temperature extremes safe* guidelines and toxicity data in Appendix K. Always know the Poor drainage or drought relative toxicity and environmental Mechanical, fertilizer or hazards of the products you use pesticide injury or recommend. Air pollutants like ozone and s!lfur dioxide. Some of these non-parasitic condi- Disease Control tions produce symptoms that can be confused easily with those of parasitic diseases. Fungal Diseases Fungi are actually tiny para- Types of Diseases sitic plants without roots, leaves And Their Identification or chlorophyll which feed on living or decaying organic matter. They reproduce and spread by means of microscopic seeds called spores. Parasitic versus Non-parasitic Diseases Some fungi; such as those that Parasitic diseases are caused help break down crop residues into by certain types of iungi, bacteria, humus, are beneficial. Fungi can and viruses that invade plants and penetrate directly into seed, leaf multiply Within their tissues. or rock tissue or can enter through Non-parasitic (non-infectious) wounds or natural openings. General diseases are caused by unfavorable types o fungal diseases are leaf growing conditions or other non- spots leading to possible defoliation; parasitic factors such as: rotting of seeds. stems. stalks, roots,

229

239 grain heads, pods, and ears; and galls, and fruit and stem rots. storage molds and wilts. Por several reasons, bacterial Diseases caused by fungi are diseases are generally much less by far the most common diseases prevalent than fungal diseases. of the reference cropsbecause Bacteria lack a resistant spore stage and are very the spores are highly resistant dependent on favorable to unfavorable conditions. They temperature and moisture are spread easily by wind, water, conditions. sail, and farm implements, and some Unlike the fungi, bacteria cannot forcibly penetrate types can also be carried by the into plant tissue but must enter through natural openings crop seeds themselves. Most iungal or wounds. diseases develop and spread much . . Although bacterial diseases more readily under high humidity can be spread by wind-driven rain, field equipment, and and moisture. An important and certain types of insects common characteristic of fungal (mainly some beetles), they are transmitted much lesi diseases is their ability to mutate rapidly than fungal diseases. to produce new races that are Viral Diseases resistant to certain fungicides. Viruses are microscopic par- Bacterial Diseases 'tidies consisting of a core of Bacteria are microscopic nucleic acid (genetic material) single cell organisms that multiply surrounded by a protein coat. by cell divison. Like the fungi, Viruses can multiply by diverting some bacteria are beneficial and living host cells into the produc- perform essential functions like tion of more virus particles and converting unavailable organic can also mutate to produce different forms of soil nutrients to available strains. They are largely spread inorganic (mineral) forms.Others by sucking insects such as aphids. invade plants and cause diseases leafhoppers, and thrips. The that produce leaf spots, wilts, relationship between these insect

230

r 240 vectors (insect that transmit "Troubllthooting Common Crop Problems." disease) and the viruses is some- Resources that give detailed des- times very specific. For example, criptions of diseases of the peanut rosette virus is transmitted reference crops can be found in by only one species of Aphid.Weeds the bibliography. are susceptible to certain viruses and serve as alternate hosts for viral diseases'which are transmit- N ted by sucking insects to crops. Methods of Disease Viruses usually do not kill, Control and plants, but can greatly reduce Effectiveness yields and quality. A wide variety-of symptoms are produced such as leaf mottling (blotching), leaf curling, chlorotic (yellow) or necrotic (dead) spots on the Prevention versu's Cure leaves, leaf striping, and Most diseases such as viruses excessive branching. and the bacterial and fungal rots How to Identify Plant Diseases of seeds, seedlings, roots, stalks, Some plant diseases can be and stems cannot be controlled once identified readily by non -prof es- they enter plant tissue. Fair to sionals right in the fiqld. In good control of fungal leafspots other cases, however, accurate can be achieved with foliar fungi- diagnosis requires a good deal of cides but this is usually unecono- field experience or even the ex- mical with low value crops like , pertise of a trained plant patho- maize, millet. and sorghum. logist and lab facilities. For Disease control methods are there- more information on identifying fore geared much more toward pre- plant diseases, see Appendix I, vention rather than cure.

231

241 Non-Chemical Disease Control Methods (removal) of diseased crop Resistant varieties: Disease plants attacked by viruses. resistance is a top priority However, roguing is not 1 among plant breeders. Breeders effective for most fungal- have located genetic sources and bacterial diseases. of resistance to some of the Crop residue management: The more serious diseases, especial- burning or plowing under of ly viruses and other types that crop residues is an effective lack effective or economical prevention method for a few chemical control measures. diseases like Southern stem However, resistance does not rot of peanuts. mean 100 percent immunity, and the ability of viruses Other management practices: and fungi to mutate into new Several of these may help races has posed some problems. minimize certain disease problems: not cultivating Disease-free seed: Some plants while they are wet; diseases like bacterial blight avoiding crop injury at or and common mosaic virus of before harvest; irrigating beans can be carried by the in the morning when sprinklers seeds. The use of certified or hand watering are used so seed that is disease-free is that crop leaves are dry at an important management prac- night; using raised beds to tice in many bean-growing improve drainage and disin- areas. fecting tools. Controlling_ host plants and Crop rotation: This can reduce insect vectors: This'is the incidence of many fungal especially important for and bacterial diseases, espe- controlling certain viral cially those that are soil-. diseases and involves the borne, but will have little removal of host weeds and effect on viruses. There is other natural vegetation nothing wrong with monoculture that serve as sources of from a disease standpoint as infection. In some cases, long as resistant varieties non-susceptible barrier are being continually developed crops are planted around and introduced in response to a field in a 15-20 m wide new problems. However, this is strip to "decontaminate" unlikely in the developing sucking insects before countries. they reach the susceptible 'Intercropping: This practice may crop. (Usually not practical reduce or intensify disease pro- for the small farmer). Also blems, depending on the crop Included is the roguing

232

242 mixtures involved and whether Fungicide applications to they share some diseases in the soil are sometimes common. helpful. Some fungicides Chemical Disease Control Methods like PCNB (Terrachlor), Vitavax (Carboxin), and I Fungicides can be applied Benlate (benom )jl) can be to seeds, the soil, and crop applied as spra s or.dusts leaves and will provide fair. to the seed furrow or to to good control of certain the row during crop growth fungal diseases. They are to control certain fungal mainly applied as protectants. stem and root rots. Seed treatment with a Such soil applications are fungicide dust or liquid seldom necessary or econo- will effectively prevent mical for maize, sorghum, seed rots (pre-emergence and millet,.but can be "damping off") caused by profitable on high-yield- soil fungi. This method ing peanut and bean crops will also kill any fungal where disease problems diseases borne on the exist. seedcoat surface such as loose smut and covered Foliar fungicides can be smut which attack adult applied as dusts or sprays sorghum plants. to crop foliage to control fungal leaf spot diseases. Since seed treatments Most foliar fungicides act mainly protect the seed, as protectants to help. they are not as effective prevent the occurence or at preventing seedling spread of leaf spots. blights (rots) and Some of the recently seedling root rots. A developed systemic fungi- :systematic seed treatment cides like Benlate (beno- fungicide called Vitavax myl) and Martect (Thiaben- (Carboxin) gives somewhat -dazole) also have erradi- better control. cant properties. Seed:treatments will not Most fOliar fungicides control any soil-borne have tittle or no effect or airborne fungal diseases on bacterial leaf spots,. that attack older plants but copper base fungicides such as leafspots, stalk provide fair to good control. -* rots, stem rots, and root rots.

233

t 243 Foliar fungicides are sidues, the development of usually not economical resistant races of fungi and for maize, sorghum, and bacteria, and occasional millet, but are often phytotoxicity. essential for control'of fiJ Ctrcospora leaf spot in Use of insecticides to control planutsand can be very insect vectors: Is seldom profitable in thiscase. completely effective since 100 Their use on beans may percent control is impossible. be justified where yields Integrated Disease Control. are in the medium to high range and fungal, Integrated disease control leaf spots become'serious. O involves the combined use of non- Soil sterilants like methyl chemical and chemical methods. bromide, formaldehyde, Basamid, Except for'the mercury base fungi- and Vapam will control soil, . fungi, bacteria, insects, cides sometimes used as seed weeds, and nematodes. They are applied in advance of dressings, the fungicides pose few planting and allowed to toxic or environmental threats, disperse before the seeds are sown. Soil sterilants unlike some insecticides. The are frequently used on seed- incentive for integrated disease beds for growing tobacco and vegetable transplants, but control is based on economics and are too expensive,for use the fact_that many diseases cannot with-the reference crops. be controlled adequately with Antibiotics like Streptomycin and Terramycin are bacteri- chemicals. cides used as,foliar sprays or transplant dips to control certain bacterial diseases. Other antibiotics like Kamusin (Kasugamycin) and Blasticidin are effectIve againdt*certain fungal diseases such as rice blast, and are widely used in Japan. Their high cost makes them uneconomical for use on the reference crops. There are several problems associated with antibiotics, namely re-

234 244 'sr

Seedling leaves, but this can be con- Major Diseases of fused easily with injury by wind, The Reference Crops wind-blown sand, fertilizers, herbicides, and insects. Examine the below-ground portion of the plants and look for rotted seeds, soft rot of the stems near the soil surface, Maize and rotted, discolored roots. Control: Use good quality seed, free

of molds and damage, that has been " treated with a fungicide like Captan orkrasan (thiram) for protection Maize Fungal Diseas3s dgring germination. Seed treatment Seed Rots and Seedling Blights is mainly effective against seed rot: These are often referred to as Helminthosporium Leaf Blights pre-emergence and post-emergence "damping off" and are caused by soil, Several species of Helmintho- % or seed-borne fungi. Seeds may be sporium fungi attack maize. leaves, but killed before germination or seed- the two most important are H. Maydis lings may be destroyed before or (Southern leaf blight) and H. turcicum after they emerge from the ground. (Northern leaf blight). Helminthospor- 4mping off is most prevalent in cold, ium maydis is more prevalent in hot, 1:ilorly-tirained soils and with damaged humid areas, but bothspecies can occur seed (cracked seedcoat, etc.).Prob- on the same plant.. lems are less likely where conditions Symptoms of H. Maydis: There are two favor rapid germination and emergence major races of H. maydis and they have (i.e. warm weather, adequate soil different symptoms. Race "0" leaf moisture). spots are small and diamond-shaped Symptoms: Above7ground signs are when young and then elongate to about yellowing, wilting, 'and death of the 2r3 cm and may grow together, killing

235 245 41

large areas of leaf. Race,"T" leaf since they must be applied every 7-10 spots are oval and larger than those days. of race "0"and attack the husks and 'Maize iusts leaf sheaths, unlike race "0".Maize hybrids utilizing "Texas" male ster- Three types of rust attack maize: ile cytoplasm (genetic material) in common rust (Puccinia sorghi), South- their production are very suscep- ern rust (Puccinia poAysora), and tible to race "T". This became tropical rust (Physopella zeae). evident during'the severe and un- Common rust occurs more fre- expected outbreak of H. maydis race quently in. cool, moist weather and "T" in-the U.S. Corn Belt in 1970. produces small, powdery, cinnamon-

.: Most hybrids now utilize "N" male brown pustules on both surfaces of sterile cytoplasm in their produc- the leaves. Southern rust is more tion to overcome this problem. common in warm humid regions and Symptoms of H. turcicum: Northern produces smaller, lighter-colored leaf blight preters high humidity pustules than common rust. Tropical and low temperatures. Small, rust is confined to the tropical slightly oval, water-soaked spots regions of Latin America and the first appear on the lower leaves Caribbean. The pustules vary in and eventuallyicome rectangular shape from oval te round ard occur in shape and pow to a length of beneath the leaf epidermis (outer 2.5-15-cm. These lesions are grayish - layer). They are cream colored and green to tan and can cause severe very small and are sometimes surroun- defoliation. ded by a black area. Control: Resistant varieties offer Control: Resistant varieties are the the best protection. Seed treatment best protection. Fungicide sprays with a fungicide is of no help. are seldom economical. toliar fungicides give fair to good control but are seldom economical

236 246. MeiZe Downy Mildews Sorghum Downy Mildew (S. Sorghi): At least nine species of Widespread. Controls: Using reiis- Sclerospora (Sclerophthora) fungi tent varieties, removing and destroy- attack maize. At present, they are ing infected plants, and avoiding

mainly confined to parts of Asia and maize-sorghum rotations in infected . Africa, but also appear to be spread-* fields. ing th;oughout the Americas. Green Ear Disease or Graminicola Symptoms vary with the species, age Downy Mildew (S. graminicola): Occurs of plants when infected, and the on various grasses but is usually climate, but usually include chlorotic not important in maize. .striping of the leaves and leaf Sugarcane Downy Mildew (S. sacchari): sheaths, stunting, excessive tiller- Mainly confined to Asia and the South ing, and deformities of the ears and Pacific. Controls: Eliminating the tassels. A downy growth (mildew) may disease by using healthy planting occur on the undersides of the leaves material, growing maize in areas in later stages. Some of these symp- free of the disease and wtiere sugarcane toms may be confused with viruses. is.not grown extensively, removing Some of the more common downy and destroying infected plants, and dildews are listed below with their using resistant varieties. Fungicide control measures: sprays are used in some areas. Crazy Top (S. macrospora): Rare in Philippine Downy Mildew (S. philippi- the true tropics but of world-wide nensis): This is the most impbrtant distribution in temperate and warm- maize disease i the Philippinei and temperate climates. Crazy top also occurs in Nepal, India, and causes the tassel to mutate into a Indonesia. Controls: Removing and mass of leafy bunches and is pro- destroying infected plants, using voked by one or more days of flood- resistant varieties and fungicide ing before seedlings have reached sprays where economical. the four to five leaf stage.Adequate soil drainage is the only control.

237

2447 Common Smut and Head Smut row give fair to good control, but -Common smut (Ustilago maydis): are usually not economical. Seed A fungus that causes galls treatment with a fungicide is (swollen areas on plant tissue) 15- ineffective. 20 cm in size which form on any above- Fungal Stalk Rots ground part of the plant. When young, the galls are shiny and whitish with Five of the more common fungal soft interiors, but later turn into stalk rots are discussed below.They a mass of black, powdery spores. attack plants between tasseling and Early infection can kill young plants, maturity, although PythiuR stalk rot but common sOut is seldom a serious may also infect younger plants. problem. Controls: Using resistant Diplodia stalk rot; Most likely to 'varieties and avoiding mechanical occur several weeks aftee pollination. injury to plants. Good soil fer- The leaves suddenly wilt and die, tility is helpful. Galls should be turning a dull grayish-green, and the removed from plants and burned be- stalk dies 7-10 days later,. Numerous fore they rupture. small, raised, black dots can be seen on Head smut (Sphacelotheca) reil-the lower internodes of the stalk. lens): Can seriously affect yields Infected portions break readily -.and in dry; hot regions. This is a can be easily crushed. Diplodia systemic fungus that enters seedlings infected stalks usually break between withoUt showing symptoms until the the Joints (nodes). Controls: Using tasseling stage. Tassel's and ears resistant varieties, avoiding high becomeileforied and develop masses rates of N fertiri4er without adequate of black, powdery spores. Head smut K, and lower plant populations. is mainly a soil-borne disease. Gibberella stalk rot: Similar to Controls: Most varieties are resis- Diplodia except that the stalks tend tant. Crop rotation and general to break at. joints, and the inside: sanitation also provide some control. of the stalk is pinkish-red. The stomp Soil applied fungicides in the seed. black dots found on the lower portion

238 248 I. of; the stalk can be scraped off with pollination when it causes the lower a fingernail, unlike those of Diplodia. internodes to ripen prematurely and Controls: See Diplodia, shred, causing breakage at the base' Fusarium stalk rot: Similar to of the plant.The inner stalk has Gibberella and a charred appearance due to the

it. Diplo- presence of numerous black dots dia. (sclerotia). Controls: Charcoal rot Pythium stalk rot: Most likely to can be reduced in irrigated fields occur during long periods of hot, by maintaining a good soil moisture humid weather. Usually attacks a content during dry spells after tas- single internode near the soil sur- seling; see also Diplodia. face and causes a brown, soft, water- Fungal Ear and Kernel Rots soaked rot that collapses the stem. Maize can be attacked by a num- Stems do not break off but fall ber of ear and kernel rots, especially over,and plants may remain green for when very wet weather occurs from several weeks afterwards. Pythium silking to harvest. Insect and bird usually occurs around tasseling time damage of stalks and ears also in- but may also affect younger plants. creases susceptibility. It is easily confused with Erwinia Diplodia ear rot: Causes early-infect- bacterial stalk rot. Controls: ed ears to have bleached husks, while Using resistant varieties. normal husks are still green. Ears Charcoal rot (Macrophomina phaseoli); \are shrunken, and the husks seem to Attacks maize, sorghum, soybeans, li\glued together due to the fungus beans, cotton, and others. It is groWlni in-between. Ears infected most prevalent under very hot, dry later in'the season seem normal from conditions and first attacks-seedling the outside\but have a white mold roots where it produces brown, water- that usually staT at the base of soaked lesions which eventually turn the kernels. In severe cases, black black. The fungus usually does not fruiting bodies can be seen on the invade the stalk until well after husks and on the sides of the kernels.

239 249 Controls: Ears that mature with the Maize Bacterial Diseases tips pointed downward are less sus- Erwinia stalk rot: Causes symptoms ceptible. Good husk covering is similar to Pythium (see fungal stalk also helpful as is an early harvest rots). Controls: Using resistant and proper storage at a safe moisture varieties and good drainage. content. Bacterial leaf blight (Stewart's wilt): Gibberella ear rot (G. zeae): More Transmitted by certain types prevalent in cool, humid areas and of maize beetles and by the seed. causes a pink to bright red rot start- Sweet maize is more susceptible. Symp- ing at the ear tips. G. fujikuroi toms are pale green to yellow streaks is the most common ear rot worldwide on the leaves, usually appearing after and is similar in appearance. Both tasseling. The streaks die and may types also produce a cotton-like kill the leaf. The stem may also be- pink growth over the kernels, and come infected, leading to wilting of infected grain is toxic to humans, the plant. Controls: Using resistant pigs, and birds. Controls: See varieties, early use of insecticides Diplodia. to control insect vectors. Fusarium ear rot: Favored by dry, Maize Viral Diseases warm weather and similar to Maize is attacked by some 25 Gibberella. virus or virus-like diseases which are Nigrospora ear rot: Causes the cob transmitted mainly by aphids and leaf- to be discolored and easily shredded. hoppers. Alternate host plants like The interior is gray instead of white. Johnsongrass, sorghum, and sugarcane Kernels are poorly filled and can be play an important role in the spread easily pushed into the partially of most of them. Symptoms can be con- rotted cob. Spore masses in the form fusing and may often be caused by other of black spots are found at the base problems such as nutrient deficiencies. of the kernels. Controls: Balanced Some of the more prevalent viruses soil fertility; see Diplodia. are dealt with below:

240 250 1.1

Maize streak virus: A major problem causes yellowing of the young leaves in many areas of Africa and trans- which later turn red. The Rio Grande mitted by several species of leaf- strain produces spots at the bases hopper (Cicadullina spp.). Early of young leaves, followed by a yellow signs are tiny round scattered spots striping. Controls: Resistant vari- on the youngest leaves which enlarge etiet; insect cGntrol. parallel to the leaf veins.Broken Sugarcane mosaic: Occurs /here maize yellow streaks later appear and run is grown next to sugarcane rnd causes along the veins. Controls: Resistant yellow spots and streaks. Controls: varieties; leafhopper control. Using resistant varieties of sugar-

Maize dwarf mosaic: Spread by several cane. y types of aphids and a wide range of Sorghum alternate hosts, including Johnson- grass (a sorghum relative) and sorghum. Leaves of infected plants Fungal Diseases develop a yellow-green mosaic pattern, Seed rots and seedling blights: See mainly on the bases of the younger maize. leaves. Foliage becomes purple or Downy mildews:Sorghum is attacked purple-red as plants mature, severe by three species of downy mildew stunting may occur, and few plants (S. macrospora, S. sorghi, S. grami- produce normal ears. Controls: nicola). (Refer to maize for details). Using resistant varieties. Destruc- Controls: Using resistant varieties tion of alternate hosts and insect and rotation with broad-leaf crops. control. Many forage -type sorghums are very Maize stunt virus: Spread by several susceptible to sorghum downy mildew types of leafhopper (Dalbulus, sorghi) and should not be planted Ealdulus, Graminella) and known as on ground where grain sorghum will be "achaparramiento" in Latin America. sown if the disease is present. Now thought to be a virus-like Covered kernel smut (phacelotheca organism. The Mesa Central strain sorghi): Carried by the seed and

241 251 \ penetrates the young seedlings. and spores are scattered by wind and Plants appear normal until heading rain over the soil where they sqvive time when the kernels are replaced to infect the next crop. Controls: by light-gray or brown, cone-shaped Seed treatment will prevent the; smut galls full of black spores. spread from field to field, but. will Controls: Seed .tatment with a not stop infection from sporesal-

/ fungicl's is very effective since ready in thelield. Resistant vari- the spores are carried on the surface. eties should be used and infected Resistant varieties have been plants removed, and burned. developed. Grain (Read) Molds Loose kernel smut (S. cruenta):- These are caused by several Very common in Asia and Africa. As species of fungi that aremost prev- with covered smut, the spores are alent when sorghum matures during wet carried on the planting seed and in- weather. Seed becomes heavily molded vade young seedlings. Long, pointed and will germinate poorly if planted. smut galls are formed on the grain Controls: Photo-sensitive varieties heads, and infected plants may be escape head mold by maturing during stunted and show increased tillering. drier weather. Other types can be Unlike covered smut, loose smut sown to mature during, drier weather. spores may cause infections of late 'Open headed varieties are somewhat emerging grain heads on otherwise less susceptible than those with com- healthy plants. Controls: Same as pact heads. Work in India has' shown for covered smut. 'that head molds can be reduced by Head smut (S. reiliana): The most spraying the heads with Captan or damaging of the smuts. Destroys the Benlate (benomyl) plus a sticker entire head and replaces it with a immediately after a heavy rain, but mass of dark brown, powdery spores. this may not be cost effective. A large gall covered with a whitish Sorghum Rust membrane bulges out of the boot at This is caused by the fungus heading time. The gall ruptures Puccinia purTurea which produces

242 252 raised brownish pustules on both Fungal Stalk Rots sides of the leaves. This disease Charcoal rot (Macrophomina phaseoli is most common under high humidity see maize): A serious disease of but.is usually confined to the older, dryland sorghum. Losses are increas- mature leaves. Controls: Using ing in India, Ethiopia, Tanzania, and resist-Ant varieties. Fungicides Upper Volta. It is the most serious are not usually economical. sorghum disease in Nicaragua and also Anthracnose causes serious losses in Mexico and This disease is caused by the Colombia. Charcoal rot is especially fungus Collectotrichum graminicola severe when grain filling takes place which attacks the leaves, producing during high soil temperatures and tan to reddish lesions that are drought. Controls: See maize. round to oval and have soft, sunken Milo disease (Periconia circinata): centers. It may also cause a stalk Presently confined to the U.S. and rot called red rot. Controls: attacks the roots as weil as the Using resistant varieties. stalks. Even young plants may be Other Fungal Leaf Spots affected. The first symptoms are Sooty stripe (Ramulispora stunting and slight leaf rolling. sorghi), zonate leaf spot (Cloe- The tips and margins of older leaves socercospora sorghi), and oval leaf turn light yellow, and all the leaves spot, (Ramulispora sorghicola) are eventually become affected. Splitting the main fungal leaf* spots in West the base of the stalk lengthwise Africa, along with anthracnose. reveals a dark red discoloration in Controls: Resistant varieties the center. Roots are alo dark red. offer the best means of control. Controls: Resistant varieties. Removal of host plants like Guinea- Red stalk rot (Collectotrichum gramini- grass, Bermudagrass, and Paragrass cola): The stalk rot phase of anchrac- helps. nose. The outside basal portion of the stalk becomes red or purple:, If the stalk is split lengthwise, the inner

243 253 pith showi a reddish discoloration control. which may be continuous or. blotchy.

The flower stem may be similarly . Millet affected. Controls: See anthracnose. Bacterial Diseases Several bacterial leaf dis- Downy mildew (Sclerospora graminicola): eases attack sorghum and are favored Can attack millet as early as the by warm, humid weather. Yield losses seedling stage. The systemic fungus usually are not serious. Seed treat- causes the leaves to become yellowish ment with a fungicide, crop rotation, and undei wet conditions a downy and resistant varieties are the best white mildew may occur on the under- controls. sides of the leaves. Affected seed- Sorghum Viral Diseases lings may die within a month without Maize dwarf mosaic and sugarcane mos- producing any tillers. The symptoms aic produce very similar symptoms on may first appear on the upper leaves sorghum. The mottled light and dark of the main stem or on the tillers. green mosaic pattern is usually most The first leaf affected normally prevalent on the upper two to three shows damage only on the lower por- leaves and often includes longitudi- tion, but subsequent leaves suffer nal white or yellow streaks. Vari- increasing infection.Heads may be eties with a red pigment may show a partially or.totally deformed. Con- . "red leaf" symptom consisting of red trol: Many local varieties have good stripes with dead centers. Controls: resistance. The International Crops see maize. Research Institute for the Semi-Arid Yellow sorghum stunt: A virus-like Tropics (ICRISAT) achieved excellent organism that is spread by leafhop- control of downy mildew by treating pers. Plants become dwarfed with planting seed with a newly developed leaves bunched together at the top. systemic fungicide from Ciba Geigy Leaves develop a yellow cream color. known as GCA 48/988. Controls: Resistant varieties; insect Grain smut (Tolypossporium penicil-

244 254 liriae) : Fungi infect the young mil- Peanuts let florets on the seed head and replace them with plumb galls full Foliar Fungal Diseases of black powdery spores. Controls: Foliar fungal diseases can Use resistant varieties and general seriously reduce yields of both nuts sanitation. Seed treatment with a' and hay, and the decaying fallen fungicide is probably not very effec- leaves provide organic matter for tive. incubating soil-borne diseases like Ergot:(Claviceps fusiformis):Com- Southern stem rot. mon,but generally not serious. The Cercospora Leafspot: Attacks airborne fungal spores infect the peanuts worldwide, but Virginia types young florets before grain.development (see Chapter 3) are somewhat less and produce a sweet sticky liquid susceptible than the Spanish-Valencia called honeydew, which is pink or red. types. It is encouraged by wet con- The grain head later takes on a ditions. bottle-brush appearance due to the Symptoms: Two species of Cercospora tormation of dark-colored hard struc- fungi are involved. Early leafepot tures called sclerotia. Controls: (C. arachidicola) is usually the Burn infected heads. first to appear and produces round, Rust (Puccinia penniseti): Some- brownish-red spots surrounded by a times serious on late millet but yellow halo. Late leafspbt (C. per- ,- 'usually not with early millet. sonata) occurs later in the season Leaf spots: Several fungal leaf and produces darker spots that may or spots attack millet but are usually may not have halos. Both leafspots not serious. may also occur on the stems and leaf petioles (leaf stems) as the disease progresses. Severe defoliation can result, which affects yields as well as the perfofmance of mechanical pullers, which require bulky bushes

245 255 2

for satisfactory operation.Controls: it is the most serious and widespread Crop rotation :helps reduce early ground disease attacking peanuts and infections. Even though Virginia also affects beans, soybeans, other types show some resistance, foliar legumes, potatoes, tomatoes, and fungicides are usually essential in other crops. It is favored by warm, most cases and are applied as preven- wet conditions. . tatives. Peanuts are a relatively Symptots: In the early stages, some high value crop, which makes use of of the leaves on a few branches folia: fungicides very economical. usually turn yellowish. Under wet Specific recommendations are given conditions, a white cotton-like mold in the next unit. occurs on the lower stem near the Peanut Rust (Puccinia arachis): This soil surface and on any decaying disease is presently confined to organic debris on the soil. Fungal Latin America and the Caribbean. It bodies called sclerotia appear on causes small orange to brown raised the affected areas and are light pustules on the leaves, mainly on the brown to brownish red and about the undersides. It can spread rapidly size' of mustard seeds. The leaves under hot, humid conditions, and begin a gradual wilt, but at first leaf drop can be severe. The stems, seem to recover at night. ,Eventually, petioles and pegs can also be the entire plant can die. The pegs affected. Controls: As with leaf- are destroyed, leaving many pods spot, fungicide sprays or dusts are imbedded in the ground.- The disease the only effective control. can also cause pod rot. Controls: Ground Diseases There is no way to control this dis- Ground diseases caused by ease once plants are affected, but fungi are sometimes hard to detect it can be effectively suppressed

and identify and can drastically through a combination of chemical - reduce yields. and cultural controli given below: Southern stem Rot: Also known as o Crop rotations with maize, sorghum, and other grass fam- Southern E;light, wilt and white mold, ily.plants.

,. 246 256 Deep burial of all crop resi- rotting in the ground. Affected seeds dues using a mtldboard plow. break down rapidly, but,early -examine- Coarse trash like maize and sorghum stalks need to be chopped tion will show them to be covered with up manually or with a disk har- a growth caused by various species of row before plowing. Residues left on the surUce serve as a fungus. breeding ground for the fungus. Seedling blight is often referred. to as Planting peanuts on a flat Aspergillus crown rot and is caused by field or on a ridge. Seed furrows should not have depres- Aspergillus niger, a blacksooty fungus. sions which cause poor drain- True crown rot is more accurately used age. to describe the disease when it attacks Avoiding cultivation which throws soil into the crop row, older plants past_theste4Alastage. especially when plants-are The stem tissue just below ground level young. This can cause stem injury and burial of young is attacked on young seedlings shortly plants, which greatly increases after they emerge, and the fungus susceptibility to stem rot and crown rot. quickly spreads up the stem, covering Control of Cercospora leafspot it with a mass of black spores.The and other foliar diseases with stem will then suffer a total' collapse. fungicides to minimize defolil- ation, since fallen leaves Contributing factors: Soils that have also serve as breeding grounds been continually cropped to peanuts for the fungus. for long periods have more problems Applications of soil fungicides like PCNB (Terrachlor) and Vita-with seed rots and seedling blight*. vax (Carboxin) in a band over, Excessively deep planting weakens the the row at planting or at early \ pegging stage. These give fair stem and increases susceptibility. \Seeds to good protection where stem may also be damaged as they are bein rot problems are serious. (See the next unit for specific deshelled. Controls: Seed treatment recommendations.) with fungicides gives good control; Seed Rot and Seedling Blight (Pre- usually a combination of two fungicides and Post-Emergence "Damping Off") is needed to provide control of allspe-\\ Pre-emergence rot: It is not unusual cies. Recommendations are given in the \ to find germinating peanut seeds

247

257 next unit. Attention should also be A. flavus produce aflatoxin, a. . . giVen to planting depth and crop. . potentcarcinogen, (cancer-causing rotation. agent) and toxin that can affect Sclerotinia Blight birds, humans, and other mammals. This is somewhat similar:but Harvested pods are free of aflatoxin less common. Affected plants have except where they have been broken a white fungal growth attached to or damaged by termites, hoeing, rotted areas of the stem which may threshing or rough handling. The extend from below the soil surface development of Aspergillus and other 0 / up into some or all of the indivi- storage molds largely can be pre- dual runners. Infected stem tissue vented by timely harvest, separation is very shredded and contains' many of damaged kernels, and rapid drying black fungal bodies. Pegs and nuts of meist.pods. are also attacked. Control is Viral Diseases usually not needed but ajungicide Rosette virus: The most serious called Botran (dicloran) is some- disease of peanuts in Africa, espe- times applied as a spray in the U.S. cially in the wetter areas. It is Peg and Pod Rots spread by onespecies of aphid (Aphis, Several types of fiungi includ- craccivora) and has several'alter- ing Sclerotium and Sclerotinia attack nate host plants; including Euphorbin the pegg-40-pods. Soil 'SCerilants hirta, a weed.Plants become are sometimes applied before plant- sevdrely,stuntedand the younger ing in the U.S., but this; would sel- leaves turn yellow and 'mottled. dom.be economical or feasiile for Emerging leaves remain small and small farmers. Crop rotation is become curled and yellow. Early helpful. planting and close spacing appear to Aspergillus flavus is a fungal mold reduce the incidence of rosette that attacks stored seed but is virus. Affected plants should be sometimes found in the field-. Under removed and destroyed, and aphid certain conditions, some strains of control should;be considered.

248 258 . -1> Destruction of alternate host plants bacterial blight, and several viruses. is helpful. Resistant varieties Disease-free certified seed is very have' been developed in Senegal. 'difficult* to obtain in Latin America Spotted wilt virus: Caused by and presently makes up less than 3 tomato wilt virus and spread by percent of the bean seed planted several types of thrips. Affected there. plants have leaves with light green Control of seed-borne fungi: Many and yellow patterns, often in large fungi are carried, onIr in the seed, patches or in the form of ring coat,and seed treatment with conven- spots. Leaves are usually mis- tional fungicides like Arasan (thi- shapen and puckered, and the plants ram) and Captari (Orthocide) will con- take on a bunched appearance. Toma- trol them.. Others like anthracnose toes, potatoes, lettuce, peppers, are carried deeper in the seed and ornamental plants, and several are usually unaffected by seed treat- types of weed serve as alternate ment. Systemic fungicides like Ben -

hosts. It is usually not serious. ,late(benomyl) have shown some promise in these cases. Foliar applica- Beans tions of systemic fungicides during the latter half of the growing season have significantly reduced the Seed-Bornf Diseases incidence of seed-borne anthracnose Beanssuffer heavy disease in the harvested seed, but are losses worldwiie, and one of the si e. Delayed harvesting and pod major reasons is the high preva- c ntact with the soil surface during lence of seed-borne diseases. rowth can increase seed-borne ais- According to CIAT, more than half ase problems. of the major bean diseases can be ontrol of seed-borne bacteria: Seed transmitted by the seed; these treatments14A will not control intern- include anthracnose, damping off, ally-borne bacterial diseases on / root and stem rots, bacterial wilt, beans.. Seed produ4ed in drier areas

24it 259 I. 04

using strict sanitary and cultural Avoiding contamination of virT .gin ground with unclean tools,' practices such as crop rotation and animal or green manure con-

inspection is less likely to be con- , taining bean residue or dirty irrigation water. taminated. A Treating seed with Arasan Cqntrol of seed-borne viruses: Cur-. (thiram), Zineb, Demosan, rent seed treatments are ineffec- TM, Vitavax (carboxin) or Benlate at 1-3 active ingre- tive against seed-borne viruses. dient per kg to give partial Control involves the production of control. disease-free seed in areas where Applying Benlate or PCNB over the seed furrow after plant- vectors and hosts can be controlled. ing to give good control. Fungal Diseases Pre-Emergence Rot: Seed treatment Anthracnose (Colleotrichum lindemuthi- with fungicides is very effective. anum): Anthracnose is of worldwide (See melee and peanuts.) importance,in cool to moderate tem- Root Rots: Beanstare very suscep- peratures and wet conditions and is tible to roof rots caused by Rhi- spread by seed, soil, crop debris,

zoctonia, Fusarium, Sclerotium, and rain, and tools. It produces elon- / other fungi. Symptoms include red- gated reddish-brown to purple cankers dish or.brown lesiOns on the hypo- on stems and leaf veins. Pods have . 4 cotyls (below-grOund portion of the sunken spots with pink centers and stem) and 'rotting of the lateral darker borders. Infected seeds may roots from one to several weeks be discolored and have dark brown to after emergence. Wilting and leaf black cankers. Anthracnose is sel- yellowing may or may not occur. doma problem in hot, dry areas; Controls: Controls: In temperate, areas. plant- Use disease-free seed. ing only after soils hsve -Do not grow beans more than warmed up Once every two or three years Good drainagg on the same field (includes cowpeas, Ulna beans).* Crop rotation I

24 250.

.260 Avoid working in fields when sprays (see next section). the plants are wet. Plow under bean residues. Angular Leafspot (ISiriopsis griseola): Seed treatment with fungi- This disease causes gfay or brown cides is only partially effective. angular lesions on the leaves which Preventative applications of foliar eventually lead to premature defoli- fungicides have variable results. ation. Pods may be affected with Rust (Uromyces phaseoli): Rust is oval to round spots with reddish- of worldwide distribution and also brown centers and seeds may be shriv- attacks cowpeas and lima beans. elled. The disease is carried by Losses are heaviest when plants are the seed, but contaminated plant infected at or before flowering. debris is a much more common source The disease is favored 'by damp of infection. Control: Using disease- weather and cool nights and can free seed, crop-rotation, and remov- infect both the leaves and the pods. ing previously infected crop debris First symptoms usually appear on from the field before planting. the lower leaf surface as whitish, Seed treatment with a fungicide (Ben- slightly raised spots. The spots late has given good results) and grow into reddish-brown pustules fungicide sprays may help. which may reach.1-2 mmln diameter Sclerotinia Blight (white mold): within a week. The entire leaf Causes water-soaked lesions and a begins to yellow, then turns brown white mold on leaves and pods (see and dies. Rust is not carried on also peanuts). It can be controlled the seed, but the spores persist by crop rotation and foliar sprays in bean residues. There are many of Benlate, Dichlone, Dicloran, races of rust, and bean varieties PCNB or Thiabendazole around early- vary in their resistance to them. to mid-bloom. Irrigation intensi- Controls: fies this disease. /- Crop rotation. Sulfur dust or fungicide

251 261 Web Blight (Thanatephorus cucumeris): to good control. Systemics . / This disease can be a major limiting like Benlate are recommended / under high rainfall. factor to been production under high temperature and humidi y. party Bacterial Diseases other crops are also ffected. The Common Blight (Xanthomonas phaseoli) fungus causes small found water- and Fuscous Blight (XanthomonasphaSe- soaked spots on thelleaveS which oli var. fuscans): Both diseases pro-

are much:lightertha/n the surround- duce the same symptoms on leaves, ing healthy tissue/and look like stems, pods and seeds. The first i they have been sclded. Young pods leaf symptoms are water-soaked spots

show. light tans"4 ots that are irre- on the.undersides which grow irregu- gular in shape but became darker larly and are surrounded by a narrow and sunken with age--they can be zone of lemon yellow tissue.These confused with anthrac ose. The spots eventually become brown and

stems, pods and leaveIII become cov- dead. The stem may become girdled ered with a spider web -type growth near the soil and break. Water- ' that is imbedded with.brownI fungal soaked spots form on the pods, grad- bodies. Web blight can be carried ually enlarge and become dark, red by the seed but ismorlcommonly and somewhat sunken. Infected seed transmitted by wind, rain, tools, may rot and shrivel. Controls: and the movement of hum ns and Disease-free,seed. \ draft animals through the, field. Crop rotation and deep plowing. Controls: Copper-base fungicides have Disease-free seed. --controlled leaf symptoms well, Cr ..t rotation with maize, but have not given good yield grasses, tobacco, ana increases. Antibiotics other non-hosts. should not be used due to the danger of causing mutations. o Planting beans in rows, not by broadcasting, to maxi- Seed treatment is not very mize air circulation. effective. Fungicide sprays give Bair ,Somp varietal resistance is

252 262 available. applied to the leaves gives Halo slight (Pseudomonas phaseoli- poor to fair control.

cola): This bacterial disease pre- Viral Diseases fers cooler temperatures thancom- 'Beans are attacked by a num- _ mon and fuscous blights. The ini- ber of viruses, many of which also tial symptoms are small,waterrsoaked attack cowpeas. Bean common mosaic, spots on the undersides of the bean yellow mosaic and cucumber mos- leaves, which eventually become aic viruses are spread by aphids. infected with greasy spots if the Bean rugose mosaic and several others attack is severe. Stem girdle or are spread by beetles. Bean golden joint rot occurs at the nodes mosaic and chlorotic mottle viruses above the seed leaves when the dis- are spread by white-flies, and curly ease results from contaminated seed. top virus by the beet leafhopper. However, leaf yellowing and malfor- Symptoms include one or more of the mation may occur without many other following: green-yellow leaf mott- external signs. Controls: ling, leaf malformation, pucke'ring, Deep plowing and crop rota- curling, plant stunting, and yellow- tion ing. Control consists largely of Removing infected plant using resistant varieties and dis- debris from the field ease-free seed, and controlling Avoiding work in the fields when the foliage is wet insects. Disease-free seed Non-Parasitic Diseases Varieties that have some Seed injury: Bean seed is very sus- resistance ceptible to seedcoat damage and Seed treatment with Strep- internal injury by improper thresh- tomycin (2.5 g active ingredient per kilogram of seed) ing and mechanical harvesting or or Kasugamycin (0.25 g active by rough handling. Damage may be ingredient per kilogram), using the slurry (liquid) invisible or produce cracks in the method. seedcoat, both of which can cause Copper-base fungicides the following seed abnormalities:

253 263 Reduced germination and seed- a constriction around the ling vigor: This can also be caused by bacteria, fungi,_ stem at the soil line, insects, fertilizer burn, and especially on light-colored herbicide injury. sandy soils. Temperatures "Baldhead": The seedling lacks a growing point. There above 35.5°C cause blossom is only a bare stump above drop if they,occur during ;the cotyledons, so no further flowering. leaf growth can occur. Detached cotyledons: Young bean seedlings need at 'least one complete cotyledon or two broken ones with more than half attached to provide adequate nutrition for emergence Chemical Disease and early growth. Dry bean seed (14-percent moisture Control or below) is the most easily dam- Recommendations aged. Bagged seed should not be dropped or thrown onto hard sue- . fates. Seed Treatment Sunscald: Intense sunlight, espe- With a Fungicide cially following cloudy and humid weather, can produce small water- soaked spots on the exposed sides Effectiveness of leaves, stems, branches and pods. Seed rots (pre-emergence damp- These spots turn reddish or brown ing off): Very good. Seedling blights (maize, sor- and may grow together into large ghum, millet, peanuts): Fair. necrotic lesions. Air pollutants Seedling root rots: Poor to and tropical spider mites can pro- fair. duce similar symptoms. Seed-borne fungal diseases: Heat Injury: High daytime tempera- Very good if the spores are carried on or close td the tures may cause lesions that form seedcoat surface as with

254 264 Se loose smut and covered smut ernment sources may come pretreated of sorghum. Poor if the dis- with a fungicide or fungicide/insec- ease is deeper inside the seed as with bean anthracnose. ticide combination. Check the label Seed-borne bacterial diseases: and look for a red, purple or green Poor. dust on the seed. Farmers can.treat Seed-borne viruses: Ineffec- seed by mixing it with the correct tive. amount of .fungicide dust. Large Seed treatments are very quantities of seed can easily be economical and are recommended for treated using an oil drum set up to all the reference crops, especially rotate on its longitudinal ails in for peanuts and the other pulses. an offset manner, bUt bean and pea- They are most beneficial under wet nut seed must be treated gently. conditions, particularly in cool Some treatments are applied as slur- weather where germination is slowed. ries (14quids); farmers should How to Treat Seed alwa,. allow label instructions. Seed from commercial or gov- Precautions: With the exception of

A mixing drum for applying in- .4ecticide and/or Fungicides to seeds prior to planting.

255 265 10

mercury compounds like Ceresan, treated seed for human or animal Semesan, and Agallol, seed treatment consumption. Combination fungicide/ fungicides are relativelynon-toxic, insecticide treatments containing although somecaa cause skin and Dieldrin or other Class 1 and 2 eye irritation. Avoid using mer- compounds should be handled with cury compounds. NEVER use any rubber gloves.

Table 10 Recommendations for Seed Treatment

The following recommendations are based on current information from North Carolina State University and CIAT.

CROP TREATMENT 21211111a 02/100 lbs of seed Maize Arasan (thiram) 509; dust 1.5 2.5' Captan (Orthocide) 75% dust 0.75 1.25 Sor hum Dichlone (Phygon) 50% dust 0.6 1.0 NOTE: Increase dosage on sorghum by about 25-50%, since it has more surface area per kg. Peanuts Arasan (thiram) 50% dust. 2.0-2.5 3.0-4.0 Captan + Maneb (30-3Q dust) 2.0-3:0 3.0-5.0 Botran + Captan (30-30 dust) 2.0-3.0 3.0-5.0 Difolatan + Captan (30-30 dust) 2.0-3.0 3.0-5.0 Vitavax (carboxin) 75% W 2.0-3.0 3.0-5.0 Vitavax + Arasan or Captan 1.25-2.0 2.0-3.0 NOTE: The combinations are recOMmended where Aspergillus seedling blight is prevalent. Vitavax is a systemic fungicide. Innoculated peanut seed should be treated immediately before planting. Beans Arasan, Captan, Zined, Busan or Vitavax 1.0-3.0 NOTE: Seed coat infections of anthracnose have been effectively controlled with Arasan 75% dust applied at 5g/kg of seed.

'256 266 Recommendations for over the plants to settle the gran- Soil Fungicides ules to the soil. Vitavax can be applied in the same manner at early pegging using 1.1-2.25 kg/ha active ingredient. (Recommendations from Vitavax (carboxin) and PCNB North Carolina State University and (Terrachlor) are sometimes applied Clemson University.) to the seedfarrow at planting or to Beans the row soil during crop growth to Root and stem rot caused by Scleros- control soil-borne diseases like ium rolfsii: Application of PCNB at Southern stem rot and root rot. They 3.4-4.4 kg/ha of active ingredient to are rarely necessary or economical the seed and' surrounding soil at for maize, sorghum, and millet and planting has proven effective in Bra-

are usually not justifie d011pea- zil (CIAT data). nuts an4 beans unless potential Root rot caused by Rhizoctonia solani: yields are high and disease problems North Carolina State University recom- are serious. mends PCNB at 100-150 grams active Peanuts ingredient per 1000 meters.of row Southern stem rot control: Apply PCNB length applied at. planting time to preplant at active ingredient llkg/ the seed and surrounding furrow soil. ha in a band 20-30 cm wide centered over the row or,at early pegging Recommendations for stage in a band 30 -40 cm wide. Pre- Foliar Fungit _:es plant applications should be incorporated 5.0 -7.5 cm deep. When apply- Protectant versus Erradicant Fungi- ing PCNB at early pegging, direct cides the spray so that it reaches the Most fungicides like Maneb, soil at the base of the plants. If Zineb, Difolatan, and Manzate act as granules are used, don't apply them protectants by-remaining on the leaf whenthe plants are wet: Drag bags surface to prevent fungal spores from

257 267 germinating and penetrating the used for seed treatments and soil plant.' They have little or no erred- application. icant ability to stop the progress Guidelines for Applying Foliar Fungi- cides of an existing infection. However, a few fungicides like Benlate (ben- Type of Crop: Foliar fungicides are omyl) and Thiabendazole (Mertect) seldom economical for ,maize, sorghum, are actually absorbed into the leaf and millet. They will give the best tissue and translocated outwards benefit/cost ratio when used on well- toward the margins. These systemic managed peanuts and beans under con- fungicides act as erradicants as ditions where fungal leaf diseases well as protectants and also have are a limiting factor. other advantages: When to Apply: Ideally, applications They are not vulnerable to should start slightly before the being washed off the foliage by rainfall or sprinkler, onset of infection or at least before irrigation. the disease signs have become very Since they are translocated evident. This is especially impor- within the leaf, mirorm tant when non-systemic protectant foliage coverage is not as important as with the non- fungicides are used. In most grow- systemic protectant fungi- ing areas, the major fungal leaf cides. diseases are somewhat predictable as

The main: disadvantage of the sys- to their date of first appearance. . temic fungicides is that they are Fungicides are too expensive to be effective against a narrower used on a routine basis from the range of fungal diseases than most time the plants emerge. Besides, of the protectant fungicides, so most fungal diseases do not infect more care must be taken to match plants until around flowering time the product to the disease. or after. Vitavax (carboxin) and Frequency of Application: This Plantvax (oxycarboxin) are two depends on disease severity, rain- other systemic fungicides mainly fall, and type of fungicide. The

258 268

et non- systemic protectant fungicides Duter is one exception, since these can be washed off the foliage by additives increase the likelihood of rainfall (or sprinker irrigations, crop injury from that particular pro- but the systemics remain safely duct. Some fungicides already con- within the plant once they have tain stickers and spreaders, so be been absorbed. Under frequent rain- sure to read the label. fall, the protectants may have to Amount of water needed for adequate be applied as often as every four to foliage coverage: This varies with seven days. Under drier conditions, plant size, crop density, and type intervals of 10-14 days are normal. of sprayer. When using backpack Systemics are usually applied once sprayers on full-'size plants, at every 12-14 days regardless of rain- least 700 1/ha of water: is needed. fall frequency. Disease severity' Dosage Recommendations also affects application frequency Label instructions and exten- but is usually closely related to sion service recommendations are the rainfall and humidity (as* well as specific guidelines to follow.The varietal resistance). following recommendations are meant Uniform and thorough cover- to serve as general guidelines. age of crop foliage is very impor- Peanut Cercospora Leafspot: Benlate taptwhen applying fungicides. and Duter have generally proved the This is especially true for the most effective, although most other protectant products which are products, such as DithanA-45, effective only on those portions- Antracol, Bravo (Daconil), Difolatan, of the leaf surface they actually copper - sulfur, dusts, and copper-base cover. An attempt should be made sprays, also give satisfactory con -'

to cover both sides of the leaves trol. The following recommendations when using protectants. Stickers come from North Carolina State Uni- and spreaders are recommended for versity (U.S.A.) and Australia. nearly all fungicide sprays to Duter 47% WP, 425 g actual formulation per hectare. Do enhance coverage and adhesion.

259 269 not use a sticker or a Anthracnose: Literature from spreader. CIAT recommends Maneb 80% W or Benlate 50% WP, 425 g actual Zineb 75% W at 3.5g/1 of water, formulation per hectare plus Benlate at0.55 gh, Difolatan 80 W at3.5 kg/ha, and Duter 47 sticker-spreader. W at 1.2 g/l. Control is enhanced by com- Rust:.Suggestions from CIAT are 14. bining 285 g Benlate plus 1.7 kg pith for Dithane M-45 or Hancozeb ane M-45 or Manzate 200 plus 2.3 at3-4 kg /ha; Manzate D 80 W or Maneb 80 W (Dithane M-1-2) at 4 kg/ non- ph9totoxic crop oil per hectare. 10 7ha;. sulfur dust at 25-30 The oil improves penetration. 'kg/ha. Plantvax (oxycarboxin), a systemic, has been found Daconil (Bravo), 875-1200 g effective when sprayed at a rate active ingredient per hectare. of 1.8-2.5 kg/ha of the 75% WP Copper-base products like at 20 days and 40 days after copper oxychloride, copper planting or every two weeks until the end of flowering. hydroxide, and basic copper sulfate can be used at 1.85 kg Whilte mold (Sclerotini: active ingredient per hectare. North Carolina State University recommends Benlate 50 W at 1.7- Antracol 70% le can be used 2.25 kg/930 1/ha on Botran at 1.7 kg/ha. (dichloran) 75 W at 4.5 kg/930 Copper-sulfur duct: Follow 1/ha. manufacturer's recommenda- Web blight: Recommendations. tion. from CIAT are for Benlate 50 W Note: Do not feed treated hay to at 0.5'kg/ha (0.5 g/1 at 1000 1/ livestock unless only copper ha) of Brestan 60 at 0.8 kg /ha' or copper-sulfur products or Maneb ( Dlthane M-22) at are used. Duter helps 0.5 eliter: (Note:4The Maneb retard spider mite buildup. dosage seems unusually low.) Plant injury may result if Angular leaf spot: Literature a sticker-spreader is used from CIAT suggests Benlate 50 with Duster. W at 0.5 g/l, Zinib, Mancozeb, Bean Leaf Diseases: Potential bean Ferbam- sulfur- adherent (no .yields must be high to warrant the dosages given). use of foliar fungicides. Systemics Bacterial blights: Use copper- base sprays and follow label should be considered where rainfall directions. is high if they are effective against the disease involved.

260 270 I

s'N the soil where fertility or moisture Nem4odes are low. However, clayey soils can have serious nemstodeproblems, too. Since they are so tiny, nematodes seldom move more thane few Nematodes are tiny, colorless, inches a year. Unfortunately, they thread-like roundworms 0.2-0.4 mm are spread easily by soil carried on long.. There are many kinds ofplant- tools and equipment or by water run- feeding nematodes. Most live in the off from a field. soil and feed on or within plant Maize, sorghum and millet are roots using needle-like mouthparts fairly' resistant to most kinds of for piercing and sucking.They dis- nematodes, and yield losses seldom solve the roots` cell contents by exceed 10-15 percent. The pulses injecting an enzyme with produces arg most vulnerable to root lesion various reactions depending on the and'sting nematodes which feed on type of nematode. The root-knot roots, pegs, and pods. Beans and nematode causes portions of the cowpeas are attacked by root knot, roots to swell into galls or knots, root lesion, and sting nematodes \ while root lesion nematodes produce plus several other types. In Kenya, produce dark- colored lesions on the heavy infestations of root knot nema- roots. Sting nematodes and stubby- todes have reduced bean yields by up root nematodes prune the root sys- to 60 percent in some cases. tem and make it appear stubby. Root growth is often stopped and Diagnosing becomes very susceptible to attack Nematode Damage from bacteria and fungi. Nematodes are most prevalent Above-ground symptoms. are seldom and active where soil temperatures distinctive enough to make a con- are warm. They seem to prefer elusive diagnosis without examining sandier soils or'those portions of the root system, but the following

261 271 are possible indications ofnematode damages Stunting, yellowing, lack of plant vigor. However, these can be caused by many other problems--low fertility, diseases, excessive soil acidity or moisture,... for example. Wilting, even when moisture seems to be adequate and heat is not excessive.This can also be caused by'soil insects, borers, and dideases. Damage almost always occurs Root knot nematode in scattered patches in'the galls on bean roots. field and is rarely uniform. Note how they .differ This is an important charac- from nodules by actu- teristic of nematode problems. ally being paft of the root. Root sydptoms, as described baow, may be. observed if the roots, are Laboratory diagnosis is usu- carefully dug up and examined: ally needed to confirm nematode Galls or knots are a sure damage, although. root knot nematode sign of root knot nematode injury is often readily apparent. damage. These should not be

confused with the Rbizobia . Plant pathology labs in most coun- bacteria nodules attached to tries can test soil and root samples the roots of legumes!. The galls or knots caused by for nematodes. It will be necessary root knot nematodes /are; to take 10 random sub-samples within actually swollen potions of root. the field right next to the plants Othet typo of nematodes using a shovel for testing. Sample

, cause tiny, dark-colored the soil by digging down about 20- lesions, stubby roots or Lass of feeder roots. This 25 cm and discarding the soil from damage should not be con- the top 5 cm and ,from the sides of fused with that calmed by rootworms, white gfubs or the shovel. The remaining soil other insects. should be placed in a paii, making

262

272 sure some roots are included. The ceptible, butpeanutcan be

. Gra s 'family sub - samples should be mixed together attacked also crops tend tobe 1 ss vulner- and a half-liter of the soil placed able. (Cottonandeanuts can also be incl ded in the in a plastic bag. The sample Should same rotation, nce they do be prote&ted from sunlight or exces- not share the me root knot sive heat, preferably by refrigerat species. However, planting cotton immediately prior to ing it uptil mailing time. 'A lab peanuts will cause a buildup of peanut soil diseases. diagnosii.is also valuablefor planning a suitable crop rotation pro- Root lesion' nematodes (Pratyl- enchus spp.)-: Beans, cowpeas, . gram to reduce nematode numbers, peanuts, soybeans, tobacco, okra, pepper,' potatoes, sweet since different types vary in their potatoes, tomatoes, sugar crop preferenCes. cane and strawberries are among- the most susceptible. Maize is less so, and sorghum Nematode Control and millet have bette4,resistance. Sti2gnematodes (Bolonolaimus su): Beans, cowpeas, cotton, Complete eraication is soybeans, maize, millet, sorghum, sweet potatoes, tomatoes, impossible, put- ch ical and non- squash and pasture grasses chemical controls can reduce popu- are among the hosts. Tobacco and watermelons are resistant. lations to toleiable levels. Non-Chemical Controls \ Some types of tropical legume tree 'crop rotation: This is such as Prosapis spp. harbor nema- Sometimes, difficult or impractical, todes. Host country extension see since most types of nematodes have vices sometimes have a nematode spe- many crop hosts as shown below: cialist who should be consulted con:- Root crop nematodes (Meloido- cerning crop rotations and other gyne spp.): Beans, cowpeas, controls. cucumber, squash, watermelon, cantaloupes, tomatoes, Resistant varieties: Varieties differ tobacco, okra, cotton, car- somewhat in their resistance to nema- rots, lettuce, peas and todes. strawberries are very Sus-

261 273 Exposure: Plowing up roots of sus- transplant beds, but are either too ceptible crops right after harvest expensive or require specialized will expose then} to sunlight and application equipment.Some are drying, which will kill many of the very dangerous. nematodes. Non-fumigant nematocides: These Yloodin.g.: One month of flooding,fol- Include Mocap (ethoprop), Furadan. lowed by a, month of drying and a and Dasanit, and can be applied as furthcr month of flooding will granules to the crop row and are greatly reduce nematode problems, effective against some insects. but is not often feasible., Under small farmer conditions, tfiein Anta gonistic plants.: Many garden use on maize and other cereals .for books recommend inter-planting mari- nematodes only would be uneconomical golds among susceptible crops to except in cases of heavy infestations and-high potential yields. There ZbEiroknematodes. Unfortunately, . - research has shown that marigold may be some cases where their use is ' species vary in their effectiveness, e ) ustified on the pulses, especially which is limited mainly to one type peanuts. Product use guidelines for of nematode, the.root lesion nema- some of the more common nematocides:v Lode. Furthermore, marigolds do NEMAGON (DBCP, Frumazone): Comes as not kill nematodes, but starve them a liquld or granules but has been out'. This means that interplanting virtually banned in the U.S. as a is not effective, since the nema possible carcinogen. Prolonged expo- Lodes will still have a food source. sure over the years has caused testi- Marigolds would have to 'he slanted cular atrophy in males. aaunuEL exclusiyely and then followed by a from this one. crop Oceptible to root lesion FURADAN (Carbofuran): See description nematodes in order to provide some control. under Section B..Has a very low der- ma, but very high oral toxicity. TwO legume green manure or cover Nematode application guidelines are: crops, Crotalaria spectabilis (showy crotalaria 'or rattlebox) and Indigo Peanuts: Apply a-barid 30-35 cm feri hirsute (hairy indigo) can wide over the row before plant- reduce populations of most-type of ing; use 2.2-4.5 kg of active ingredient per hectare. nematodes. Needs to be worked into the soil% Soil: Good soil fertility and high 5.5-15 cm deep. soil' organic matter levels help somewhat. Maize: Apply in a band 18-36*cm wide over the row before plant- Cta'nical Controls ing and work into the top 5-10 Soil fumigants: Some of these, like cm of soil. Use 1.7-2.25 kg of methyl bromide, Vapam, Basamid and active ingredient per hectare. EDB are often 'used on vegetables or MOCAI) (Ethroprop, Prophos): Kills.

264 2 74 nematodes and soil, indects but is seeds, They often uproot young very toxic both orally and dermally. Applied like Duradan at the rate of seedlings of maize and other cer- . 1.7 -2.25 kg active ingredient per eals during the first several weeks hectare. Not recommended for most small farmers. Non-systemic. of growth as well. TEMIK (Aldicarb): A systemiclinsecti- Controls: Scarecrows are relatively cide/hematocide'with extremely high ineffective, although noise - making oral and dermal toxicity. Avoid it. devices may offer some control. It DASANIT (Terracur, fensulfothion): A non-systemic prod!t for soil is often necessary to frighten away insects and nematodes. Very high the birds front planted fields during oral and dermal toxicity. Avoid using. their usual early morning and late NEMACUR (Phenamiphos, Penamiphos): afternoon feeding times for the first A systemic product for nematodes,__ two or three weeks after planting. soil- iiisects, and above-ground sucking insects. Class 2 toxicity. Farmers sometimes soak their seeds in e Applied to peanuts' like Furadan at highly toxic insecticides like 1.7-2.85 hectare. Handle with care. Use Endrin and Dield1n and plant them or Furadan instead if possible due to use them as scattered bait.This is its much lower dermal toxicity. not only dangerous, but can lead to indiscriminate killing of wildlife. Some safer repellants are available Bird and Rodent such as Mesural 50 percent dust, which is mixed with maize before Control planting at the rate of 9-10 g/kg to repel blackbirds. Mesurol may injure maize seed under cool, wet con-

Birds ditions. Dusting seeds with Captan fungicide or soaking them in turpen- Seed-Eating Birds zine may provide a fair repellant In parts of Africa and in effect. other areas, birds like the bush Perhaps the most effective 'fowl dig up and eat freshly-planted control method is continuoalistring

265 275 flagging which uses cloth or plastic ones ut*to 5000-6000. Each

1 streamers 5-6 cm wide and 50-60 cm pair ofAllneleas can produce two young. long. The streamers are attached ' Controls: In areas prone to attack, at1.5 in intervals to strong twine the villigers build high platforms in which is strung along heavy stakes the fields and maintain noise making at least 1.2 m tall spaced-a-bat:rt. vigils, sometimes for many weeks, 15 m apart. while the grain is ripening. Govern- (1,110.ea Birds ments frequently undertake mass Que- The Quelea bird (Black-Faced lea extermination campaigns which Dioch) is a sparrow-sized weaver center around the destruction of nest- that, may be the world's most des- ing and roosting sites with explO-, tructive grain-eating bird. It is styes, flamethrowers, etc, South confined to the Sahel and savanna African authorities killed 400 mil- regions of Africa in a band running lion with aerial sprays in one four- from Senegal to Mauritania to year campaign. However, the birds Ethiopia and Somalia and ,then south usually return in undiminished num- through East and South Africa and bers within a year or two, since across into Angola. they are highly nomadic and have The birds congregate in vast extensive breeding grounds estimated nomadic colonies that feed on the to cover. two million square. miles. seeds of both natural grasses and At the present time, bird-resistant crops like millet, sorghum, rice, crop varieties are not very success- and wheat, mainly in the unripe ful against the Q uelea, and the stage. (Maize is less affected.) same seems to be true of repellants Queleas begin breeding a few weeks like Avitrol and Morkit. after the rainy season begins and Other Grain-Eating Birds build their nests in thorn trees or Blackbirds (grackles, star- swamp grasses. Studies in Senegal lings, etc.), sparrows, cockatoos, have shown that even small trees parrots, galahs and pigeons also :can hold up to 500 nests and taller feed on grain crops, though usually

266

* 276 in less awesome numbers than Queleas. Good weed control in the field Bird-resistant varieties of sorghum is helpful. (see Chapter 3) are fairly effective Leaning or fallen plants should propped up and the dry at repelling them while the grain is lower leaves'stripped off to ripening, but lose this ability when help deter climbing. maturity nears. Repellents like Avi- Many villages carry out organized killing campaigns. The tol (aminopyridine) are often used best time for such campaigns successfully in the U.S. The usual is during the dry season when the rats congregate in the result of using repellents in one few remaining pockets of green vegetation. field, however, is that the birds move on to attack other fields that Repellents like Nocotox 20 may be partly effective. are unprotected. Rats should be prevented from gaining access to stored Rodents grains and other food that can cause a buildup in populations during the dry season. (See Chapter 7.) The cane rat (Thronomya sp..) can cause- considerable losses of Nilson baits can be used. NOTE: Killing rats in the field with cereal crops during the latter poisons, traps, and other methods is stages of growth, especially if usually not a very effective long- lodging has been heavy due to high term solution. The best approach is to prevent a rat population buildup; winds or diseases. this requires area-wide coordination. ..Controls: The PC/ICE Small Farm Grain Storage manual contains a very useful sec- Rodents can be discouraged tion on rat control. from entering fields by maintaining a 2.0-3.0 m wide cleared swath around the field borders from planting until harvest. Fences made from oil palm fronds or split bamboo are also effective, especially if traps or wire snares-n-re-set--in the gaps.

267 277 F/ro m turi 7. Harvesting To Harvestn, Drying, and

Storage ea . Maize, Sorghum And Millet

For the farmer, the chillenge's When these cereal crops reach of agriculture do not end when a sue- physiologic maturity, the grain is still cessful, crop retches maturity in the too wet and soft for damage-free thresh- field. LOSS4 between maturity and .ing (separation from the stalk or ear) consumption or sale are frequently or for mold-free storage. Most small serious, especially for the small farmers let the crop dry naturally in A farmer, and are also a major contri- the field for several weeks prior to

. buting factor to the world foOd harvest, unless immediate land pre- problem. This chapter focuses on paration is needed for the next crop. specific practices that will keep Duming this "dry-down" period, the these losses at a minimum. crop is vulnerable to losses caused by several factors: Rodents: Losses are especially high where lodging or stalk breakage is severe.

410 Lodging and stalk breakage: These may occur during the dry- 0- down period and are encouraged by overly -high plant densities, low soil potassium'levels, high winds, and stalk rots. They promote rodent damage and grain r rots, especially when the ears

269 278 . ., . . or seedheads touch the soil. Beans and

Grain rots: Wet weather during Cowpeas dry-down may provoke fungal grain rots' (head molds, ear rots) or accelerate those that may have begun during grain Lossis between maturity and filling. Some small farmers harvest of beans and cowpeas` are bend the maize ears downward near maturity to prevent caused ,by: water from entering through Pod shattering: Spillage of the tips. seeds from drying pods that split can be a problem, but Weevils and other storage losses are not usually serious insects: Some storage unless harvest is delayed. insects like the rice weevil Bruchid weevils: (See section Angnmis grain methTIttotit:oga on storage.) These are not only sp.) can fly to the fields serious storage pests of pulse and infest crops from the soft crops but also can fly to the dough stage onward. Maize fields to infest beans and varieties with long, tight cowpeas by laying eggs in cracks husks ha;e good resistance, or cuts in the pods. but high-yielding varieties tend to be inadequate in this I Seed deterioration: This can respect. be a serious problem in beans and cowpeas and can occur soon Birds: Most species prefer 'after maturity if rainfall younger, softer grain but continues.* Studies by.IITA can still cause problems after have found that cowpea seed Bird-resistant sor- maturity. quality and germination decline ghum varieties lose their rapidly when harvest is delayed. repellent ability by the time In tests under wet conditions, maturity is reached. seed germination fell to 50 percent or lower within three Theft: Farmers should be encour weeks after maturity, and pre- encouraged to harvest their harvest fungicide sprays were of crops as soon after maturity little benefit in preventing as is practical. to prevent this. losses from theft. Delayed maturity: Litera:Jre from CIAT mentions that bean plants may put out new growth and flowers,during maturation under

270

279 f

.1)

high rainfall. The new involves lifting the plants and foliage can interfere with attached pods from the ground, then the proper'drying of the maturing pods and may lead to allowing them to cure (dry) in the rotting. field for a period of; from several days to four to six weeks before threshing. rea n u ts Threshing consists of separating the seeds from the seedheads, cobs or podsby beating, trampling or other Peanuts pose a special ptob- means. With peanuts, threshing lemsince the nuts do not mature separates the etas from the pegs that simultaneously. Those that ripen hold them to the plant and does not first may become detached from the include actual shelling. (With maize, pegs before the rest mature. The the term "shelling" is usually used :ling of the harvest is critical in place of "threshing".) and will be covered in the next With cereal crops and beans, the section. Small farmer has several options as to when to thresh the crop. If the matured crop has stood in the field Harvesting for some time during dry weather, the- seeds may be low enough in moisture and Threshing content to be threshed without damage right after'harvest. However, the farmer may still prefer to delay threshing for two reasons: Nearly all small farmers in The graiNmay still be too high the 'aeveloping countries harvest in moisture content to escape . spoilage if stored as loose their cereal crops and beans by seed. Grain stored in hand dild thresh them latPr. In unthreshed form on the eub, on the seedhead or in the can the case of peanuts, harveAting be safely stored eta muLL,

271 C

higher'moisture content tropics, most maize varieties reach since there is much more air physiologic maturity within 90-130 space for ventilation and further drying. days after seeding emergence or 50-58 days after 75 percent of the plants Maize stored as unhusked ears and pulses stored in their hava,produeed silks. As maturity pods are more resistant to nears, the lower leaves begin to storage insects. yellow and die off. In healthy well-nourished plants, this should Winnowing follows threshing not occur until the ears are nearly and consists of separating chaff and mature. Ideally, most of the leaves other light trash from the grain Should still be green when the husks using'wind; fan-driven air or screens. begin to turn brown. Unfortunately; Winnowing may need to be repeated such high- yieldiig plants are not

severs !times.before consumption or often seen in small farmer fields marketing and is usually supple- because of stress factors like low mented by manual removal of stones, fertility, insects, diseases, and clods, and other heavy trash. inadequate Weeding. More typically, most of the leaves are dead by the -time the plant matures.

The "black layer" method: When a Guidelines for maize kernel reaches phyliologic Harvesting and Shelling Maize maturity (maximum dry weight), the outside layer of cells at its base where it connects with the cob will die and.turft black, thus preventing any further cob-to-kernel nutrient Determining Maturity transfer. This "black layer" provides an indication of maturity. The In the 0-1000 m zone id the layer can be seen by detaching kernels

272 281 from the cob and examining their and have much higher moisture contents bases. Newly-matured kernels may when the black layer forms. have to be slit lengthwise with a The dry-down rate of maize:When maize pocketknife to expose the black plants are left standing in the field -layer. However, with older kernels. after maturity, the kernels lose about the layer can be readily seen by 0.25 - 0.5 percent moisture per day, scraping the base with the fingernail. but this can range from 0.1 - 1.0 Keep in mind that Physiologic percent depending on weather conditions maturity is not reached until all the and whether the ears are pointing kernel's milky starch, has solidified. downwards to.prevent water entry. This process begins at the tip of the kernel and moves downward Methods of Harvesting Maii'e: toward the base. The kernels at By Hand: The ears are removed by hand from the plants with the ear tip are the first to mature, or without husking. Husked ears followed by those in the middle and require a smaller storage area and are more resistant to insects, finally the ones at the lower end butmay rot more easily if stored (the difference is no more than a at a high moisture content. few days). V Mechanical: Tractor-drawn With healthy plants, kernel pickers and picker - spellers can handle one to two rows at moisture at physiologic maturity once, but self- 4ropelled com- will vary from about 28-36 percent. bines are available which can harvest up CO six to eight rows. This is usually too highofor damage- *By changing the front attach- free threshing or for mold-free ment (the "head"), combibes can also harvest other cereal storage except in the form of crops (if not overly tall) and husked ears placed in very bush beans, but cannot be used. on peanuts. Well-adjusted narrow cribs. The black layer pickers and combines should may form much earlier in the maize have losses of less than 2 percent and 4 percent re ,pectively plant's growth cycle if growing unless lodging is severe conditions are adverse. Such a kertelsewill be small and shrunken

273 282 4.

When to Begin Harvesting shelling may become serious above 28-30 percent or below 15-18 percent moisture. Harvest should begin as soon as is practical after maturity, but this depends on the farmer's harvest' Methods of Shelling Maize method and storage and drying facilities. If done too roughly or at too

Hand harvesting: Since high a moisture content, shelling can husked ears can be safely cause kernel damage such as tip loss, stored in narrow cribs (see Storage section) at up to cracking, stress cracks, and pulveri- 30-32 percent kernel moisture, iption. Studies have shown that harvest can be started at or soon after maturity if damaged kernels spoil two to five

Sesired: -.Most small farmers = times more r$idl -y during storage prefer to let the maize dry down further in the field first.than undamaged ones. Hi-lysine varieties and other floury types are Mechanical harvesting more susceptible to damage. Shelling Pickers: if narrow cribs (see storage section) are methods and guidelines for small far- . used for storage, mechanical mers include these: picking can be started once kernel moisture'is down to 30r37 percent. Traditional methods

Picker-shellers and combines: By hand: This method is. very In this case, adequate drying tedious and labor-intensive, facilities and kernel damage but causes little damage to the from shelling are the main. kernels. It is more thorough concerns. In the tropics, than other methods and also shelled maize above 14 per- allows for. separation of cent moisture will not store damaged and insect - infested more than a week to a few grain. This method is best months without spoilage. suited to small amounts. Rapid drying is essential Dry ears are placed in and usually requires forced Beating: snd beaten with sacks.. air and beated'dryers when bags large volumes are involved'. This is quicker but less thor- Kernel damage from mechanical ough than hand shelling and may cause damage. O 274 283 1

Improved methods England. Maize at too high or too low a moisture content Wooden hand -held, maize sheller: is likely to be damaged, but The model shown in the drawing was developed by the Tropical this can be checked visually. Ears must be husked first. Products Institute and has an I output of roughly 80 kg/hour. - glans are available fromICE.) Motor-driven shellers have outputs of about 1000-5000 kg/hour. other typvs of hand held shellers are available commer- The comments above also apply to this type. cially. Cobs must be husked first. Winnowing Methods Reliance on wind is the traditional method, but hand-cranked or pedal-driven fans can. be constructed easily. The larger models of the hapt-cranked ornedal- operated shellers usually are equipped with blowers.

Guidelines for Harvesting and Threshing Sorghum And Millet

Wooden, hand-held maize sheller a Determining Maturity Hand-cranked or pedal-opera= When grown under favorable ted shellers: Small, hand- conditions and good management, grain cranked models have outputs of about 50-130 kg/hour. The sorghum reaches physiologic maturity Ransomes Cobmaster.twin-feed while the stalks and most of the pedal-operated sheller has an hourly output of 750-900 kg. leaves are still green. Like maize, For details write Ransomes sorghum kernels also develop a Ltd Ipswich 1P3 9QG, "black layer" at their base when in developing countries, maturity phySiologic maturity is reached. often coincides with the start of the The layer can'be checked by pinching dry season, and, the crop may be left off some kernels from the bracts' standing in the field to dry for a that hold them to the head and number of weeks before. harvest. 4 examining their bases. If present, Crop losses during this period can the black layer can be seen without be heavy. If dry conditions prevail, splitting the kernel. the crop can be harvested at or Sorghum flowers and polli- shortly after maturity and stored on

\ - mites from the tip of the seedhead the head with little danger of downward, a progression which takes spoilage. from four to seven days. The ker- Sorghucan be harvested and . neIS mature in the same direction, threshed with a combine once kernel with those at the bottom lagging moisture reaches 25 percent. However, about a week behind those at the loose grain that is this "wet" must top. Kernel, moisture content is be dried down to around 14 pare at about 30 percent at physiologic 'within a few days to avoid.spoilage. maturity. If large amounts of grainare 0 involved, some form of forced air or Methods to Harvest Sorghum heated drying would probably be Bv Rand: The seedheads needed. T1re cur off using a knife' or sickle. Methods of Threshing Sorghum ..Mechanical: Tractor.driven or self-proped combine harvesters can harvest and Traditional methods: These thresh short (dwarf) and include pounding, beating, and medium varieties. animal trampling and are very tedious except for small quantities. Kernel damage is possible When to Harvest Sorghum unless care is taken.

In most sorghum-growing regions

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.285 Mechanical methods: Tractor- all the nuts have ripened, because ; or motor-driven stationary heavy losse4 may occur for two rea- :threshers come in many models with outputs of 600-3000 kg/ '- sons: hour. A11 but the simplest models will,also clean the threshed grain by the use of By the time the last pods shaking screens and/or blower ripen, many of those which: fans. matured earlier will have become detached from the Plans fora four-person pedal-, plants due to peg rotting. powered grain thresher/mill Thid pod "shedding" can be for sorghum, millet, and wheat especially serious when designed by VITA can be Cercospora.leafspot pauses obtained from ICE. As of 1979, premature leaf loss 'or when however, this thresher/mill. lifting occurs in diy, hard

had not been adequately field ' soils. tested and is not _suited to local village constructlon. Spdnig-Valencia/I varieties, the early-maturing kernels may sprout if kepttoo long NOTE: Millet is harvested and in the ground. The Virginia threshed much like sorghum. types have a lengthy seed dormancy period which prevents this.

I Guidelines for Likewise, if harvistint occurs to Harvesting and Threshing Peanuts early, an unddsirably" high proportion of t e kernels will be immature, - 0 shrunken, low in weight, and inferior 1 in flavor. The choice of harvesting Peanuts reach maturity when date can easily make a 400-500 kg/ha the veins on the inside of the pods difference on a high yielding rept., turn dark,. However, since the plants -' produce flowers over a period of How to determine "peak maturity": from 30-45 days, the nuts do not Vie farmer should aim for a harvest' Mature simultaneously. Unfortunately, date that will'reeOver the largest harvesting cannot be delayed until number of mature kernels before

277 286 1.

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oxcessive pod shedding or sprouting Minimizing crop losses: Pod shedding has.Occured. This is often referred can be reduCed by keeping the plants, to as "peak. maturity", and there are.. green and healthy until maturity.

no easy rules for determining it. This often requires controlling ' The pattern of flowering, pod s4tting, Cercosppra leafspot with fuPgicide nd-kexnel maturation varies from sprays or dusts. This also increases year to year due to differences in yields by prolonging ehegrowing.4 'weather and leafspot incidence. season by as much as two to three (The first 40-60lowers to bloom are weeks. Some farmers, however, may generalli,the ones that end up as object to having leafy greerfoliage mature klernels at 'peak maturity.' at harvest time, since it 'may slow Floweriqg starts about 30-45 days down the rate of field curing when after.plant emergence in warm areas the harvested bushes are placed. in and begins very slowly. In fact, stacks. In'this case,-farmers may .f most of these 40-60 flowers usually \ purposely stop their fungicide applc-o.; bloom 'Ieac theand uf4phe flowering cations late in the season to prom7te rf period,ialthough there maybe several defoliatidns. This also has the effect '"bursts!'. of,floweLng. of Making maturity more uniform,/ e4 maturity cannot be deter- although ,htlds are reduced. Such .mined br kooking at the above-ground a practice may be justified in some .-:portion of `the plants. The best regions, especially where field cur-1.. 'method is to carefully dig up a taw Ong weather is not always dry. On the------. - [.very several days beginning other hand, farmers can use'leafy ! near the end of the growing period plants fir lifestock.feed after anf exanine the pods. With-experi- - harqest ence, tle farmer can learn to esti- ft mate quite accurately how many young '010c: 'In the 1.1.S., xtension ser- pods will ripen 13,4fOre the matured vica advise against f eding pearnit pods b gin to .hed or sprout. hay; to dairy or beeflanimals if P. hag received fungicide applications,

-,. 278 87 except-in the case of copper or cop- Methods of "Lifting" the Crop: per-sulfur products.) By hand: The plants are pulled from the groUnd manually after loolsening the soil Peanut Harvesting 'with hand tools. It takes '' 1 11 about 30 hour# to pull and stack a hectare-with this Whether traditional or modern method. i Methods are used, the harvesting pro- , Animal-drawn methods: Special cess basically consists of four steps: animal-drawn lifters are available and consist of a sharpened, The taproots are cut and the , horizontal blade that is run plants are pulled (lifted) under the plants right below from the ground with the attached pods. the nuts to cut the taproots, loPsen the soil, and partially One hectare o Under traditional methods, 1 ft the plants. the plants are cured (dried) an be lifted and stilcked in in the field for up to A-6 bout 15 hours., A carefully - /operated weeding sweep (see weeks before threihing,i With; modern methods, the plants Chapter 5) about 30-40 cm ( are cured in the field for wide can be used,;butthe blade should be adiuste4 to slice 2-14 days, depending oh the whether artificial drying is rather than push soil to minimize od losses. available afterwards. Some farmers use moldboard or I lister plows on 'ridge-planted 4 The polds" are threshed frot-- the ants. peanUts. .

0-rte threshed pods are placed Tractor-drawn methods: Tractors in bags for storage and possi- can be equipped with front- ble' fur her dryink In dry mounted cutter bars and rear- 'areas,t4e pods are often mounted that lift the !TwoTwo to four row setups stored in outdoor piles. plants. are common, and some 0 the I pullers will combine two or more / Note that shelliAt the nuts from the rows into one windrow :or curing. pods is not normally a paryd he Peanut inverters are available that flip the hushes over to expose harvesting 'process, since the ker -. 1 the nuts to tle-son. nels .dry/ and store better in the plod.

Shell in dayagecan -be Tiijh unless kernel moisture is at or below lb

/percim . 279 288 do

Some General Guidelines for Lifting with the pods facing inward. The slats hold the bottom layer O Lifting the crop when the soil off the ground and also improve is too wet can weaken the pegs. air curculation. The stack' is It may cause excessive amounts built in a cone shape and the of soil to adhere to the pods top covered with a few vines to which can also slot:, down curing. help shed water. In some cases, the plants are kept in'the stacks Lifting losses can be high in until kernel moisture is down to very hard, dry soils. 8-10 percent. This may take up to four to six weeks in cool, wet If cutter blades are used, weather. they should be kept sharp and be set at a slight forward if harvest takes place at the pitch to aid in lifting the start of the dry season, the plants and loCsening the soil. plants may be stacked right on the ground.

Methods for Curing and Threshing Row or windrow curing: If artk-% Peanut:. ficial methods of drying are available or effective sun dry- The method and length of curing is possible, the plants may be cured in the field in rows , lug prior to threshing varies consid7 or windrows for two to five erably with weather conditions and days before threshing. Where post-threshing drying is less 'the availability of equipment and efficient, the curing period artificial methods of drying: The .lasts about 7-14 days so the pods will be drier at threshing most common methods are: time. The ustackpolen method: This is often used by mechanized and Windrows can be made by hand or unmechanize0, Yarmers alike through operation of a where curing weather can be wet side-delivery rake (tractor- and no means of artificial drawn). The main advantage of drying are available. windrows is that they save time when'self-propelled modern Poles are placed firmly,in the threshers are used. ground, and two slats are nailed at right angles to each The plants can be plaCed upside other about 50 cm above ground down to expose the nuts to the on each pole. After being sun. This will reduce damage in allowed to wilt, the plants weather,eather, but can lower quality arc stacked around the Dole under hot, sunny conditions.

280 289 Windrows that are overly com- intendAfor bulk storage and pact and dense increase curing for peanuts above 16 percent time and spoilage under wet con- intended for storage in loosely ditions. After a heavy rain, stacked bags under good venti- At:may be necessary to gently lation. Peanut moisture content turn the windrow to prevent at lifting may be over 35 mold. This should-be done percent. before it dries out to minimize pod-shedding. Avoid Tips on mechanized threshing: placing windrows-over depres- Hull damage and splitting is sions in the field. lowest for peanuts threshed at 25-35 percent moisture. Letting 'Methods of Threshing, the lifted plants dry down longer in the field reduces Traditional: Peanuts can be post-threshing drying require- manually threshed-by strip- ments but increases the weather ping the pods by hand or by risk. Unless the vines are dry striking the base 'of the plants enough to be easily torn apart, (above the pods) against the rough threshing action may be edge of a barrel or wooden box. needed which will increase kernel damage. Improved: A hand-cranked thresher with an output of 200 kg/hr is being marketed Shelling Peanuts in Senegal. Peanuts are not usually shelled Stationary motor-driven until shortly before consumption or threshers are cavailable. oil extraction. The shelling percent- Tractor-drawn or self-propelled threshers are used in age is abbut 68 percent (1000 kg of modern farming and pick up the unshelled peanuts yields about 680 kg plants right from the windrows. of shelled kernels), and the process Threshing Guidelines is most easily accomplished when Peanuts can be threshed any kernel moisture is below 10 percent. tire after the plants are Hand shelling is very tedious and the li_ced as long as adequate natural or artificial drying output is only about 10-20 kg/day methods are available (in the Various models of hand-cranked or case of high-moisture nuts). Further 'drying will be needed pedal-operated spellers are commer- after threshing for peanuts cially available with outputs abotit above 10 percent moisture 15-90 kg/hour.

281 290 Plans developed by VITA for a maturity. belt-driven peanut huller made from scrap motor vehicle parts When to Harvest are available from ICE; some simple Indeterminate varieties with an - - -- welding and cement work is needed. uneven maturity are usually harvested' Power can be supplied by a water in several pickings, whili determinate wheel, small motor or animal. bush-types are harvested all at once when most of the pods are dry.

Guidelines for Method of Harvesting Harvesting and Threshing Beans. The following methods. apply to And Cowpeas bush or semi-Vine varieties with uniform maturity: op By hand: The mature plants Determining Maturity are pulled from the ground and placed in piles for drying. The pods begin to turn yellow Pulling is best done in the early morning when the pods during the final stages of growth are moist to prevent shattering.- and become-brown and rather brittle Mechanized: Two basic methods once maturity is reached. Determi- are used. The plants are cut nate bush varieties and some inde- or !'glided" out of the ground using a tractor with front- terminate types have fairly even mounted horizontal blades with pod maturity, and the plants have blunt cutting edges or rotating disks operated slightly below usually lost most of their leaves the soil surface. Several rows by the time the pods have ripened. are combined into one windrow using a side-delivery rake Most indeterminate wining types which can be rearhiounted behind mature much less uniformly, and a the cutters. The windrows are dried for 5-10 days before good number of pods may ripen while threshing with tractor-drawn or most of the leaves are still green. self-propelled threshers. Seed moisture content is around Direct harvesting is popular in 30-40 percent at physiologic

282

291 the U. S. and Canada using bibliography. grain combines with modifications. Drying Threshing Methods for Beans

Beans can be threshed. manu- allyby beating the plants or bagged Very moist grain will deterio- pods with sticks once they are dry rate and spoil during storage for two enough. Whatever the method used, seasons: bean seed can be easily injured if 0 Since they are alive, the seeds consume oxygen and burn threshedtoo roughly or when too dry. up some of the'..food stored in

, Injured sed, when planted, will pro- the endosperm for energy. This respiration process produce weak, stunted plants and other duces heat, but is too slow to abnormalities(see Chapter 6 on be of Concern in dry grain. However, respiration and heat bean diseases) production are rapidly accelerated bv t:aiscure,_and the Winnowing beans: Refer to maize. moisture and heat promote rapid mold growth and spoilage in wet grain.

Drying and Storage insects like weevils .become more active and multi- Storage ply more quickly in warm, moist grain. They also produce heat and add more moisture which further increases mold growth. Grain drying andstorage are very broad subjects, andadequate NOTE: Some storage molds pro- coverage is far beyond thescope of duce toxins called mycotoxins which are this manual. Some of the more, harmful to humans and livestock. important principles and practices Aflatoxin is one example. All cereal are outlined here. More detailed and legume grains are susceptible if information can be found in the insufficiently dried or improperly references listed in the stored, especially peanuts.

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292 . -

Fortunately, the farmers do 30°C and 70 percent relative not have to dry their grain down to humidity if grain moisture is not above 13.0-13.5 percent for zero percent moisture, since it can maize and sorghum,.and 16 per- tolerate about 12-30 percent depend- cent for millet. Bagged maize and sorghum can be stored at up ing on the type, the form in which to 15 percent moisture, since it is stored (ears or seedheads vs. ventilation is much better. loose grain), how it is stored (bags On the cob or seedhead: vs. bins, etc.)', and the surrounding Husked maize ears can be safely placed in cribs for storage and temperature and humidity. Most further drying at kernel mois- loose grain'has about 12-15 percent ture contents up to 3') percent if all the ears are within moisture at marketing or prior to 30 cm of open air. Sorghum processing for consumption, and crop and millet seedheadiTairilSo be safely stored and dried yields are usually calculated on down from high moisture contents about a 14 percent moisture basis. if kept in small stacks or hung from rafters. In fact, there are several disadvantages to drying grain below this Peanuts range. Where grain is sold by weight For safe bulk storage of pods, overdrying will reduce the farmer's kernel moisture content should not be returns from a sale. It is also above 10 percent: Pods can be safely costly where artificial drying, is placed in bags at kernel moisture used anti can lead to cracking, dis- contents up to 16 percent and will coloration, and poor germination. dry down adequately if loosely stackedftrovided ventilation is suf- . Grain Moisture Guidelines for Safe ficient. Otherwise, forced air will Storage be needed.

Maize, Sorghum, Millet Beans and Cowpeas

Loose: Threshed grain can be Threshed seed stored in bins safely stored in silos or or silo' should not be above 13 per- bins for up to a year at 25- cent moisture. Bagged seed can be

284 293 164

safely stored at up to 15 percent Add 5-10 teaspoons of oven- moisture. Unthreshed pods can be dry table salt, seal the bottle with a dry lid or cork, kept at much higher moisture contents and shake for several minutes. and will dry down well if ventila- If the 'salt sticks fo the inside of the bottle, the grain has tion is adequate. over 15% moisture.

Oven method: A grain sample of known weight should be ovendried for one or How to Determine two hours at 130 °C if ground or 72-9C Grain Moisture hours at 100°C if in whole form. After reweighing, moisture content can be calculated as follows (cover Grain moisture should always the grain to avoid moisture reabsorb- be calculated on a wet weight basis. tion while it is cooling off): In other words, 100 kg of 15 percent

moisture maize contains 15 kg of % moisture water and 85 kg of dry matter. Thete of origi- = Wet Weight-Dry Weight Wet Weight are several ways of measuring grain nal sample .moisture, some of which can be easily done on the farm with very Biting, pinching, rattling, feeling :' little equipment; Most farmers will use such methods

Salt and bottle method: This quick for estimating grain moisture with and r.nsy method isaccurate to with- varying success, depending on experi- in 0.5% but will only indicate the ence. They should not be relied grain is, above or below 15% mois- upon wheke accuracy is important as ture, the maximum limit for storing in the case of grain stored in bulk maize and sorghum in bags. (bias or' silos).. Thoroughly dry out a bottle of about 100 ml capacity and f:11 it three-quarters full with maize.

285

294 How to estimate the final weight of begin to absorb moisture grain after drying. and becomemetter.

s Air flow through the grain and air moisture content (rela4ve 1,inal grain % dry matter humidity) have. the biggest weight af-= before drying x original influence on drying. The ter drying % dry matter weight lower the air's relative humi- after drying dity the treater its ability to pick up moisture from the grain and carry it away. Example: A farmer has 2000 kg of Warm air has .a much higher shelled maize at 20% moisture.Row moisture-holding capacity than much will this amount of maize weigh cool air. This means that warm air is more effective at after it has been dried down to 14% picking up moisture from wet moisture? grain than cool. /pair when the relative humidity is low. Solution: To obtain the percent Supplemental heat from either dry matter meeded for the formula, sunlight or fuel can be very" subtract grain moisture content effective at.improving the drying ability of cool air if from 100 pprcent then use the it is very damp (high relatiVe formula. humidity). For each 0.55°C rise in temperature, the relative humidity of the heated Final grain 80% . 1860 ke air is reduceelpy about 2 weight af-= 86%X2000 kg= of grain percent. ter drying after drying The ratet of drying slows down to 14% as grain moisture content falls, since the remaining moisture is given up less readily. Unless Some Important Grain DE-37i-- the airis very hot and dry, a Principles point is eventually reached I; beyond which' no further drying Warm, dry, moving air encour- occurs. This is known as the ages more rapid drying to a equilibrium moisture content. lower moisture content than cool, damp, still air. In fact, if the air becomes too -damp, grain may, actually

286 295 Methods of Drying o Traditional sun-drying is the Fuel.Heated and/or Forced-Air most common method used by Drying: For large quantities small farmers and consists of of grain, fuel-heated and/or spreading the grain out in a forced-air drying is used. shallow layer on the ground for For the individual small sun exposure. Depending on the farmer such drying may not be weather, the thickness of the feasible. however, the pro- grain layer, and the amount cedure can be justified on a of stirring, the results cooperative basis and can offer range from poor to good. The several advantages: disadvantages are poor air circulation, contamination Farmers can harvest with dust and stones, and their crops earlier moisture absorption from the at a higher moisture ground. The PC/ICE Small content to avoid losses Farm Grain Storage Manual caused by natural field recommends general improve- drying. Earlier har- ments for this system. vesting also permits earlier landprepara- Enclosed solar drying reduces tion and planting of sun-drying time, requires no the next crop. 6 fuel, and can be used on other crops like cassava, copra, The grain may end up fruits, and vegetables. at a lower, safer However, grain can be damaged moisture content for or have its germination storage and keep in impaired by the extremely - better Condition. Its high temperature (65-80°C) market value may also that can build up under the be higher. plastic or glass sheet. Solar drying may not dry On the other hand, construction down grain rapidly enough andwel costs may outweigh when operated under very. . these advantages*, so a thorough cloudy conditions (See bibli- analysis of the factors should ography for refereirces con- be conducted before dqciding taining plans for solar to buy or build such dryers. driers.)

287 296 S t 4 4 Temperature Guidelines for Grain Drying Excessively high drying tem7 estimated to be about 30 percent peratures can cause cracking, break- worldwide. Small farmers are espe- ing, and discoloration of the cially vulnerable to such losses kernels and also lower germination since their traditional storage and protein quality. Peanuts may methods are often inadequate to pro- become bitter if dried at tempera- tect the crop.. In many cases, tures above32-35°C, and overdrying farMers may be forceerto sell much increases splitting and skin slip- of their grain shortly. after harvest page during shelling. Beans are at a low price rather than risk also best dried at low temperatures. spoilage.A few months later, they The maximum safe drying tem- may end up buying it back at a much peraturedepends on the crop and higher price.. By improving their its use: storage facilities, farmers can Crop and Use Maximum Safe ensure more food for th'eir families, Drling more stable prices, and better Temperature quality seed for planting. Crop Livestock feed ,,75°C Cereal grains improvement programs should place for human food a higher priority on providing ample except rice 6ORC Milling for safe storage for the expected pro- flour 60°C' duction increases. Brewery uses 45°C For planting seed 45 °C Principles of Safe Storage Rice for food 45°C Grain must be adequately Beans for food 35 °C 35oc dried before being put into Peanuts storage, although maize stored on the ear and other crops stored in the form Storige of seedheads or pods can often be stored and dried Storage losses of grain due at the same time using cribs or loose stacks. 4 to molds, insects, and rodents are

288

. 9 Undamaged, winnowed grain baskets, and gourds are alsofre- has a much-longer storage life.. Uncleaned grain quently used. While such methods reduces air movement, and may work well with small amounts of the dirt and chaff hold grain, they are not well suited to moisture and encourage molds- and insects. Daiaged grain large quantities. deteriorates two to five Improved Storage Wt. times more rapidly than undamaged grain. The PC/ICE Small Farm Grain Grain shouldbe kept as cool Storage manual contains design de- as s-possible and protected tails and guidelines for many types rom.fluctuations in outside temperatures that encourage of improved storage. The major condensation. and moisture points 'are summarized briefly here. buildup inside the container. Storing in sacks made of bur- Grain should be protected from storage insects and lap, local grasses or cotton does rodents. not afford much protection against Containers and buildings., rodents,' insects or moisture.How- must be waterproof and free from groundwater. ever, sacks are easy tb label and New grain should be stored move around, and grain can be stored separately from.older grain. zt about 2 percent higher moisture The old grain .should be used than is needed for airtight storage first. , (i.e. about 15 percent versus 13 The grain should be checked every two or three weeks for percent). For sack storage: signs of heating and insects.' The walls and the roof of Traditional Storage Methods the'storage building should be waterproof. If a fafmer's production is Sacks should be stacked on small, it is often stored in the platforms (pallets) raised family dwelling. Maize ears and off the floor or on a plastic sheet. They should seedheads are commonly hung from 4 not lean directly against rafters in the cooking aria, the walls. smoke acting as an insect deter- The sacks should be / stacked in a way that favors rent. Clay pots, /closely -woven good ventilation..

289 298 tl

O A

The building should be insect- by, grain respiration and any insects and rodent-proof. already present. For successfhl air- The sacks should be sprayed ,. or fumigated for insects, but tight storage: 'only when grain will not be alone grain should not be consumed directly by humans above 1241 percent moisture. or animals ((seed grains). The containers must be. made 4_,Siloa-and-Sins made from airtight 'by using metal, sheet metal, mud bricks, cement plastic, cement (with vapor barrierYor a waterproofing blocks or cement witch metal staves material like _tar, oil-baot . , can be built with capacities rang- paint or pitch. ing from 500-4500 kg of.dried, . Containers should be filled to'the top to exclude as -threafied grain. Some cthem can much air as possible before be made virtually airtight. However, sealing. whenever grain is stoned.in such Airtight storage should not be used where the containers. large quantities, more care must be must be frequently opened, taken to ensure that it is dell since the added air will make the system ineffective dried. Unless well insulated, the for controlling insects. containers should be shaded:to pre- Containers, especially metal ones, should be Shaded to vent large. temperature variations 1 prevent condensation and which cause moisture Migration, moisture migration. condensation, and spoilage of Crib storage: See dryihg methods. grain at the top and bottom. Airtight storage in sealed gourds, underground pits, plastic bags, drums, and bins provides Insect Control excellent insect control and also In Stored Grain prevents the grain from reabsorbing moisture from humid outside air. The 'Jr present in the container Weevils and grain beetles' when it is sealed is soon used up feed on grain in both the adult and

:' 290 f. 293 et

larval stages. In addition, the temperatureincreases from 10°C larvae of several. types of moths to 26°C, storage insect activity increases, and life cycles are attack the seeds. Aside from the reduced from about eight weeks to actual losses due to feeding,, _three weeks. "At,optimum temperatures, 50 insects couldtheoreti- storage insects promote mold and cally multiply to,302 million in spoilage of grain by adding moisture just four months! Activity and breeding shows coosiderably below and increasing temperature. A heavy 10 ° -C and above 35 C, and destioccurs infestation can increase grain below about 5 °C or above 59' C. mairure-content.by 5-10 percent Moisture: Storage insects prefer under-dried grain, but Can s ill within several months. Even-if the cause serious problems in grain grain doer not spoil; it may be as dry as 12-13 percent. Grain moisture content has to be 9 per- rendered unmarketable bthe pres- cent or below before activity ence of insects or the .physical ceases, and this degree of dryness is difficult to achieve and damage caused by their feeding. maintain. Grain can become infested Storage practices: Storing new both in the field ar during grain next to old grain or using storage facilities or sacks that "storage. Some storage insects like have not been disinfected are 9 * the maize weevil, rice and- sure ways of inviting infestations. angoumis grain moth.whi.J: er...ack T122, of Storage Insects and their 41encification cereal grains and the bruchid It is useful to beable to 4 beetles that attack pulaes,thave precisely identifythe types of wings-and can` infest grain ,in the-. insects attacking a farmer's grain field. These and other types can' for three reasons: also begin attacking grain during Not all insects found in storage. The adults lay eggs on grain are serious pest's. On the other hand, lack of or in the grain, and the deVeloping Visible grain damage does larvae hollow out the kernels. not necessarily indicaee that the insects are harm Factors Favoring Infestation less or minor pests, since Temperature: This'is the' it may take some weeks .for i\) most, important factor,. As damage to become aarent.

291

7) Although control measures tions of the container or sack, are fairly similar for most storage insects, there are since infestations often develop some differences. and spread from very localized Same storage insects are areas or "hot spots" where tempera- known as secondary and ter- tiary pests since they feed ture'and moisture may be very high. mainly on grain which is Controlling Stored Grain Insects cracked or already damaged by primary pests. The pres- ierlyrecognition of 'an ence of these non-primary infestation is very important for pests often indicates that more serious pests areat reducing potential grain losses. work.' Stored grain should be closely The Small Farm Grain checked every several weeks for Storage manual has a very complete signs of an insect buildup. Exit identification guide to cereal grain holes in the kernels, cobweb-like pests, while the Insect Pests guide accumulations-Onjticks and maize mentioned in the bibliography has ears, and the presence of adult pictures'of both cereal and pulse insects are sure signs. When sam- storage insects. pling grain, the farmer should

Checking for Infestations examine Wnels from various sec- Early.recognition of an tions of the container or sack, .infestation is very important for since infestations often develop and spread from/very localized areas la reducing potential grain losses. Stored grain should be closely or "hot spots" where temperature and checked every several weeks for moisture may be very high. signs of an insect buildup. Exit The Small Farm Grain Storage holes in the kernels, cobweb-like manual contains a detailed section accumulations 'on sacks and maize on non-chemical and chemical con- ears, and the presence of adult trols for storage insects.A brief insects are sure signs. When summary is given here plus some sampling grain, the farmer should additional information from other examine kernels from various sec- sources. t

292 301 0 Pre-storage Guidelines Sand, burned cow dung, wood ashes, and lime Be sure the grain is well give varying results. dried and cleaned. Sand helps exclude air by Clean out and repair the filling in the spaces. It storage facility. This in- also scratches the insects' cludes sweeping out old grain shells which can lead to and debris and patching all dehydration and death if holes and cracks where the. grain is already very insects might hide or mois- dry (9-10 percent moisture): ture might enter. The other materials may have some insecticidal properties. Spray or dust the facility It was discovered by CIAT with an approved insecticide that adding wood ash to (more on this further along). bean seed at the rate of one Disinfect used grain sacks part to three reduced bruchid before filling by boiling, weevil infestations by spraying with an approved about 80 percent if applied insecticide_or placing before the insects appeared. them on a hot tin roof. Slaked lima (calcium hyro- xide) or burned lime Non-Chemical Controls (calcium oxide added at for Storage Insects 4-8 parts per 100 is also Unhusked: Storing maize in farily effective (both the form of unhusked ears types are caustic). is somewhat effective. Plants: In some areas, Sunning the grain: Beetles certain plants are known and weevils will leave to have insecticidal prop- grain if it is placed in the erties and are mixed with hot sun in a shallow layer. the grain. However, this usually will Vegetable oil. The not kill all the eggs and larvae oils of peanuts, inside the kernels. sesame, coconut, Smoking the grain: By building cottonseed, and mustard- a smoky fire under a platform or seed have given excel- maize crib, many of the insects lent, protection from can be killed by both the smoke bruchid infestation in and heat. beans and cowpeas when added at the rate of Mixing materials with the grain: 0.5-1.0 percent (5-10 ml Effectiveness varies with the sub- per kg of seed). Pro- stance used, but control can be tection lasts for up quite good in some cases. to six months and does

293 302 not affect the physical vary in their susceptibility to appearance of the grain different insecticides and resis- since it is absorbed. tance to Lindane and Malathion has Airtight storage: See storage methods. become a problem in many areas. Chemical Controls for Actellic (pirimiphos-methyl) is a Storage Insects newer product that has proven very Grain that will be stored effective. Two other sources of only a few weeks or even up to two to information on storage insect three months may not warrant theuse control are: of insecticides. However, the hest African Rural Storage Center time to treat grain is when it is IITA first put into storage, before an PMB 5320 Ibadan, Nigeria infestation becomes serious. --CAUTTON1: Some-insecticides like--- Tropical Stored Products Institute Malathion, Lindane, Actellic, and London Woad Pyrethrins can actually be mixed Slough, SL3 7HL Bucks, England with food grain without. harmful RODENT CONTROL IN STORED GRAIN effects or residues if used cor- The Small Farm Grain Storage rectly. Many other insecticides manual contains a very complete would make the grain very toxic section on rodent control. and unsuitable for consumption. Many farmers are not aware of these differences and in fact may refer to all insecticides by one name such as "DDT". Where*to obtain recommendations: The Small Farm Grain Storage manual gives recommendations for treating both grain and storage areas. However, storage insects

294 303 Lessons of the "Green Revolution"

The "Green Revolution" of the Supported by a "package" of 1960's and 1970's was really the complementary improved practices first organized attempt to develop involving factors like fertilizer yield improving practices for use, pest control, and plant staple food crops in the developing spacing, the new varieties were world. Most of the efforts of the adopted in many developing regions. Green Revolution were directed to- By 1972 -1973, some 33 million wards a number of the cereals, name- hectares in Africa and Asia were ly wheat, rice, and maize. were being sown to the high-yielding A major impetus was the wheat and rice varieties. Average development of short-strewed-Vail- yields were increased about 100 per- eties of wheat, rice and maize that cent for rice compared with tradi- would respond well to high rates of tional varieties; fertilizer, especially nitrogen, Despite these increases, the without lodging. efficacy of the Green RevOlution in The term "revolution" is qvercoming hunger and rural poverty really a misnomer; nearly two de- in the developing world is a hotly cades of plant breeding And local debated issue worthy of a manual in adaptive research were required itself. There is no doubt that the before the new wheat and rice Revolution has been the major factor varieties were ready for widespread behind the gains in food production introduction in India and Pakistan. in many developing countries during The true origins actually go back the past 15-20 years and has als6 to breeding programs for wheat and laid a solid basis for additional. maize in Mexico in the 1940's and agricultural research in the region. to similar work with rice in the It was conducted in a spirit of Philippines. humanitarian and largely apolitical

295 304 international cooperation that non. renewable resource with limited world reserves. Fortunately, should be commended. there is a growing awareness of On the other hand, it has not the need for an appropriate technology in harmony with both the proved to b7e the hoped-for panacea environment and economics. for several reasons: An important lesson learned is The high yielding variety that increased production does not, (HYV) "packages" it devel- automatically improve rural well- oped required relatively being. In some parts of India, high levels of inputs for example, the HYV package (fertilizers, pesticides, actually had a negativt effect on and, in some cases, irriga- income distribution, rural employ- tion pumps) and investment. ment, and dietary habits. A dis- At least initially, the turbing number of small landholders smaller farmers were often and tenant farmers were squeezed bypassed due to deficiencies off the land by the new production in the infrustructure that economics, and urban industrializa- made it difficult for them tion was insufficient to provide 55olitTin-both the-credit r han_emploment fer20croulag and the inputs. Unless was favored over grain legumes, special provisions were made sometimes resulting in actual to provide small farmers declines in_pulse_production and credit, lending institutions consumption. With a had case of naturally favored the larger Western economic ethnocentricity, ones. This situation has many "experts" argued that this improved considerably over was the necessary price to pay for the paft decade in many modernizing agriculture along "big areas, but is still a seri- is better" lines. O ous problem. m The high costs of these in- Fortunately, there is a growing puts, some of which are very petroleum-dependent (i.e. realization that the small farmer nitrogen fertilizer and pump- must be included in agricultural ing fuel), raises doubts about their continued practi- development which should be tied cality, estpecially in view into integrated rural development of the current energy crisis. Fertilizer rates are often so that nutrition, health, educa- well above the threshold of tion and general rural welfare diminishing returns in the case of nitrogen and phos- are also considered. In fact, as phorus; the latter is a the small farm family's income and

296

305

O production increases, receptivity Agricultural extension work- to these other programs is usually ers will have a central role inthis enhanced. effort to extend the benefits of the 4 Given Revolution. By spreading the The Green Revolution is far knowledge gained in trials conducted from over. Rather, its goals are by the major research institutes to being redefined and extended to increase productin of traditional other food crops. Future progress crops, agriclutural extension work- the will largely depend on how ,* ers will help ensure that the Green developing world handles twokey Revolution truly serves to improve issues: the lives of small farmers and their The conservationof natural families\in the developing world. resources and thetotal environment.

Choosing appropriatescales of production: The Western

yet evidencestrongly suggests thatsmall, intensively

most efficient. This brings cutiplttitin:utienio:saarrearth: reform, as-well asthe ultimate-goals of agricultural development. The conventional approach of tryingto integrate thesmall farmer into a modernagri-business system usuallyfails (as it. did in-the U.S.). Others feel the goal shouldbe to enable the marginalsmall farm family toachieve self- sufficiency with asmall surplus left overfor education and generalwelfare.

297

306 AppendixA Measurements and Conversioris

Area Weight., INECTAREibal = 10.000 sq. meters = 1 KILQGRAM dg) =, 1000 grains (g) 2.47 acres = 1.43 manzanas 2.2 pounds (lbs.) = 35.2 ounciiTaY (Central America) 1 POUND (lb.) = 16 oz. c 454 g = 0.45 kg 1 ACRE = 4000 sq. meters r, 4840 sq. Yards = 43,560 sq. ft. = 0.4 1 OUNCE (oz) = 28.4 g hectares = 0.58 manzanas (Central 1 METRIC TON.= 1000 kg = 2202 lbs. America) 1 LONG TON = 2240 lbs: 1 SHORT TON = 1 MAOANA (Central America) = 2000 lbs. 10,000 sq. varas = 7000 sq. meters = 8370 sq. yards = 1.73 1 QUINTAL = 100 lbs. (Latin America); (metric) acres z 0.7 hectares 112 lbs. (British); 100 kg Length Volume 1 METER (m) = 100 cm =1000 mm = 1LITER (1) = 1000 cubic centimeters 39.37 inches (in.) = 3.28 feet(ft.) (cc) = 1000 milliliters (ml) = 1.06 U.S. quarts 1 CENTIMETER (cm) = 10 mm = 0.4 in. 1 GALLON (U.S.) = 3.78 liters = 1 INCH (in.) = 2.54 cm = 25.4 mm 3780 cc (ml) 1 VARA (Latin America) = 32.8 in. = 1 FLUID OUNCE = 30 cc (ml) = 2 level 83.7 cm tablespoons (measuring type) 1 KILOMETER (km) = 1000 m =b.625 miles 1 MILE =' 1.6 km = 1600 m = 5280 ft.

299

307 .1......

Miscellaneous Conversions Lbs./acre X 1.12 = kg/ba; lbs/acre X 1.73 = lbs/manzana , Kg/ha X 0.89 = lbs./acre; kg/ha X 1.54 = lbs./manzana Lbs./manzana X 0.58 = lbs./acre; lbs./manzana X 0165 = kg/ha o , Temperature:.C =(F0- 32) X 0.55 F°=(C° X.1.8) + 32

...

i 300 i /

, 7 30(9 / Appendix B How to Conducta 0

Result Test 14

varia- asinterested in the When is Result bility of benefitsfrom a new Testing Needed? practice as they arein the averagebenefit. A practice that-produc es-large-benefits_ on somefarms but little or is unlikely To testresponses to an none on-others improved practiceunder to gainwide acceptance. actual farm:ngconditions: Research stationconditions are often moreideal or at The Procedure least different fromactual on-farm conditions.What Clearlydescribe the practice works well under the more to be tested controlled 'situationof the region into station may be lessthan sat- Divide the test isfactory in farmers'fields zones: The work area may where soil andmanagement are IFTsignificant variations elevation, likely to be muchless than in soils,rainfall, etc. It is optimal'. `farming systems, -important todivide the test- in different To test responses ing region intoseparate zones geographic regions if they differenough from profitability each other towarrant sepa- To measure the The of a new practice raterecommendations. zones-will depend variability 4 number of To measure the on yourarea's diversity,' N\NNof results: Farmers are just

361.

309 F

the complexity of the prac- If high average benefit is tice yo 4 are testing, and expected from the new prac- time aO budget, limitations. tice as opposed to the tra- In most cases you will be ditional one, fewer farms deali'g with no more than need to be included than 4 two v three test zones within if the average benefit is a mu icipality. lower. Dec de on the number of farms If a large variation is to/be included per test zone: expected in farm to farm N*urally', the more tests and results, more farms need f4rms that are included per to be included than if a test zone, the more repre- smaller variation is ex- kentative the results"will be pected. /and themore specific wilt.be

. the recommendation that Extension workeis ideally ' follows. However, costs will be higher and so will time should consult an experienced re- requirements. searcher or extension officer in Two. factors determine the deciding_how_mAny number of farms that should be in - in a result test. If professional diudedin a test area advice is not available it may be

NUMBER OF FARMS TO INCLUDE IN A RESULT TEST

/ If you expect an And if you expect yield Then you should include

/ average i9crease . variation between farms this number of farms in over normal yields within the region to your test: (10 maximum) 4 of: be: . 100 percent Quite variable 6 Fairly consistent 4

50 Percent Quite variable 9 Fairly consistent 25 percent Quite variable 10 Fairly consistent 6

302 better to proceed with result tests Ideally, the farms shspld be chosed at random, .but this is using less precise sampling methods. never completely practical The table tvlow is based on a 500- due to the limitations im- posed by accessibility and 1000 farm work area. farmer cooperation. However, Decide on how long to run a the less the choice of farms result test: If the expected is confined to a particular' benefits of the new practice class of farms and the more are likely to be significantly you choose farms on an "as' related to weather conditions they come" basis, the.closer during the growing period, the you will be to achieving a test should be repeated over valid representation. several years. This is ofteri This principle is much easier the case with tests involving ta violated than one might ex- fertilizer use and changes pect. For instance, it is in plant density and tends to easier to work with farms be true with most other prac- close to a road, with familiar tices, at least to some extent. farmers .or with farms where Repeat testing is especially good results can be expected. Andicat ed-lf-the-first-trial Such biases can totally dis- takes place during an unusual credit the results. weather year.Long-term weather records can help de- a Decide what kind of control termine this, but if not plot is needed: If the re- available, local extension- sult test is to compare an ists and farmers can be of old practice with e new One; a control or check plot will . help. be necessary. However, if a Select individual farms: It totally new crop is being in- is important that selected' troduced rather than a new farms be representative practiceor new, variety, no rather than "typical". The control plot is needed. participating farMs should reflect a cross-section of Choose the location and size those in the test area so of the plots: Plot location that trial results can be will depend a lot on the feel- converted into recommenda- ings of the cooperating far- tions generally suitable mer. This is no problem, as for the entire area. Re- long as he or she does not member also that you should purposely,select the best be just as interested in de- piece of ground on the farm. termining the variation of Random choice is the best response among farms as in method here unless parts of the average overall response. the farm have been subjected Farmers do not harvest averages: 303 .-.

311 to very unusual management sionists is to take better practices such as ultrahigh care of the test plot than fertilizer applications. the control plot. Such pre- Both the test plot and the ferential treatment celil com- control plot should be in the pletely invalidate the results, same field and preferably Documentation is vital. All adjoining each other. This inputs used should be measured helps ensure that both plots and recorded to 'the extent are subjected to the same possible. Weather data such variables. In fact, it may as rainfall, hail, and unusual be best to avoid using farms temperature extremes should where the two plots cannot, also be recorded if possible be located in the same field. along with any visual differ- The plots should be large ences between the test and enough so that the usual control plot during growth. farming methods can be followed, Collecting Data: No conclu- yet small enough so that the sions can be drawn from the results are clearly visible. result tests until yields The 'test and th6-Ubntrol-plot-- .--hiffebeen-measured,The__go_al do not have to be the same is to weigh the harvest from size. The test plot can be the test plot and an equal - a portion of it serving as area of control plot. The the control plot. extensionist and the farmer Conducting and supervising should decide on a harvest the test: The farmer and date and arrangements should his or her usual extra workers be made to obtain an accurate should handle all the land scale. Gross yields from preparation, planting, weed- both plots can be measured ing, and other operations . at the same time and then normally associated with the converted to a kg/ha, lbs./ crop. They should also apply acre or other locally used the new practice themselves yield standard. under the guidance of the However, you should always extension worker(s). This obtain a yield 12211 prior assures that the result test to the actual harvest date is fully'representative of :just in case the plots are actual farming conditions. inadvertantly harvested Make sure thatall variables without measuring yields be- other than the practice or fore the agreed upon date. input being tested&are held A properly collected random constant. One common error yield sample is usually of both farmers and exten- accurate within 5 percent of the actual yield and is a

304

312 r

cheap insurance policy. given unless a completely new or unknown input is in- Analysis of the results: volved.Much of the choice Good records are essential. to depends on the economic con- any valid analysis of the dition and receptiveness 'f results. By far the best way the local farmers. of interpeting the results is to run a standard statistical Result demonstrations: In- analysis of the yield data. puts should ordinarily not You do not need formal train- be subsidized unless there ing in statistics to do this. is still.some'uncertainty Appendix F gives easy to about the profitability of. follow instructions for the new practice, in which carrying out a statistical case it probably should not analysis which will enable be at the demonstration you to determine the standard phase anyway. deviation (a measure of the NOTE: If subsidies are pro- variability of responses vided, be sure to include from the average). .the true costs of. the inputs when doing a cost /benefit Calculate the standard deviation, since it serves as study.' basis for giving realistic Reducing the number of farm' yield expectations when fats: making recommendations to Result tests:Reducing'the farmers. number Of'tests may make the test results unrekesentk. tive for the area. Reducinp the Risk To Participating Result demos: Reducing their Farmers number will not affect the demonstration principle, but Subsidizing inputs: may slow the rate of mass acceptance by farmers. Result tests: There are two Reducing plot size: schools Of thought here. Result tests:Plot aize Some extension specialists should be large enough to feel that all new inputs allow normal growing praC- for the test plots 'should tices to be followed." Rather be provided free to the than cut plot size below . farmer. They feel this this limit, subsidies should' makes it easier to find be offered. collaborators and also helps assure control over the Result demos: Let the far- plots. Others.leel'that mers choose their oyn plot . no compensation should-be size-s-rs-long-sa-ncrrTm3-1 grow-

/ 305

313 ing practices can be followed.-,

. Guaranteeing the price orthe.' yield: The extension agency may guarantee a certain yield or market price to.a cooperating former', perhaps in the- form of a purchase contract. This should only be done with result tests. Demon- strations should stand-on their own.

.306

314 Appendix C How to Conduct Resul Demonstration

scale, the main concernis-maxi- Examine the muleffective expOsurewhen sefict-- _____Recommendation that Will be Demonstrated ing sites.However, if therecommend- ation involved issuited to several types of soils orother variations commonly found in thelocal area, MAe'suie that the recommendati. SP411" -be sure to include somefarms in . . is , . . selec- . each category. Here ate some Adapted to localgrowing conditions. Lion guidelines: Within the economic meansof s Choose KeyFarmers most of the local farmers. These are not necessarily the best or 'the most pro- AdeT.Tately tested under local gressive farmers, since farming comOitions these may be regarded as being too exceptionalby Do not turn Select Demonstration other farmers. down a "progressive"farmer, Sites. but concentrateorseeking out influentialfarmers. Since the goal of a result 5' Chose Conspicuous'Sites 1pmonstration is to promote accep- Sites should be near roads, -. tdnce trails.or public gathering places.

Since th'e goal of a result Group Demonstrations on Rented or Donated Lana dealonstration is to promote accep- These can be very effective, tance of a new practice on a mass but the group should be a 307

315 pre-existing one, rather on hand. The extensionist should than being specially organ- thoroughly- understand the what, how, ized on-the-spot to conduct the demonstration. andAyvof the procedures involved Special Factors iri Ferti- in preparing and growing the demon- lizer Demonstrations stration plot. Do not use a field that has received unusually heavy rates of fertilizer in the Supervision and past. Fertilizer demonstra- Management tions give the most spee- tacular visual responses and yield differences on low fertility land, but do not The extensionist should be purposely seek out unusual:IV-- present during the application of poor land for the demonstration. any new procedure(s) involved with

o The "Spontaneous" Demon- the demonstration plot toassure stration: Another approach that the farmer does themcorrectly. which can be very effective in certain cases is to look To make the demonstrationrealistic, for a farmer's field that th4farmer and his or herusual already demonstrates the value of what you are trying help should do most of the work. to promote. One disadvantige Avoid the strong tendency to is that there is usually no control plot for comparison. favor the "new practice". plot through overly careful tending or Preparing for protecting it from limiting factors The Demonstration without regard to cost.Visiting After selecting the sites, farmers can often easily spot these the extension worker should discuss atypical factors,.whichmay serious- , the demonstration with the farmer, ly affect the demonstration promo- including the approxiMate dates of tional value. Important operations such as planting, fertilizer application, etc. Make scare the necessary inputs are

308

316 Observation see the demonstration during the And Records crop's groloth'at any timewhen the desired results can'be clearly. seen (such as larger, greener plants The main objective of demon- resulting from fertilizer use). stration plots is to promote improved Final yield results should be dis- practices, but they can -lso provide counted conservat ively. some very useful information in re- Organized sessions for visit- turn for the small amount of extra ing farmers should be arranged if the work required to keep records and new practice requires explanation or accurately measure yields. Here new skills, both of which are very -- are some suggestions: likely. this is known as a method- Maintain some kind of chron- result demonstration and such a ological record of each demonstration, noting such session should be conducted by a things as date and amount of qualified and locally-experienced input application, weather conditions, visual observa- extension worker fluent in the tions, etc. local language. Make a yield estimate using the random sample technique The real test of a demon- explained in Appendix L. , stration is how rapidly farmers begin to adopt the new practice. e Check these estimates with what the participating far- SOME CAUTIONS: mers claim for theiryields. Do not use a result demon- Promotion and stration to test the out- Followup come of a recommendation. That is what a result test is designed to do. Result Demonstrations are supposed demonstrations are for promoting practices that have to serve as "living" examples of already been largely locally the benefits of an improved practice proven. Never undertake a result demonstration unless (or "package of practices").Neigh- you are reasonably sure the - boring farmers should be invited to practice is beneficial.

309

317 Do not promise too much in the way of results. Be conserva- tive. Do not run a demonstration on your own land. Do not sacrifice quality of work for quantity of work. Do not favOr one demonstration over another.

AM.

310

318 Appendix D How to Conduct An Elementary Statistical Analysis

A result test consists of a tice over the old practice. number of individual trials on The standard deviation: This representative farms within a local indicates how much the individual results vary from the area in order to compare a new overall averages. It is the practice with an old one.The indicator of the variability of responses around their results. of these trials provide the average. Remember that farmers seldom harvest "averages" final basis for making specific, and are very interested in locally adapted recommendations to knowing the likely variation in benefits. farmers. In order to correctly The calculations are not dif- interpret a result test, the yield ficult if you follow these standard results must be given at least an elementary statistical analysis to procedures: 1. Arrange the dataln:column determine the two most important form, as in the table on the measures of the new practice's next page. actual benefits: 2. Calculate the following aver- The average benefit: This ages by adding up the appro- is the average yield priate columns and dividing increase of the new prac- by the number of individual trials involved. (Refer to

311 319 table on the next page.) c. Average benefit (new over old a. Average (mean) yield for practice): the old (control) practice. 6.5 bu./acre b. Average (mean) yield for d. Standard deviation the new practice 2.8 bu./acre or 16% c. Average benefit: the average yield increase of the 6. Interpret the Data: Once the new practice compared to average benefit and the stan- the old one. dard deviation has been cal- 3. The Square of the Benefit: culated, you can answer four key questions which are used This is a standard statisti- to come up with a recommen- cal procedure used to calcu- dation based on the test late the standard deviation. However, the differences results: between the squares of the a. What was the average individual benefits have no increase in yield from significance. What is impor- the new practice? tant is the sum of the Solution using the data squares, since it is from id Step 5: this that the standard deviation is determined. 6.5 100 = 38% 172 x 4. Calculate the standard deviation: It is the most impor- b. What is the minimum tant statistic you will increase in yield that derive from the results farmers can expect three since it shows the variabil- out of four times? ity of responses from the SolutionwMultiply the average. The procedure for standard deviation as a calculating the standard . percentage (16%) by 0.7, deviation is best shown by a mathematical constant the following example. used in statistics. Then 5. Summarize the Data subtract the result from the average increase in a. Average yield of yield expressed as a per- the new practice: centage (38 %). 23.6 bu./acre b. Average yield of Solution using above data: old practice (con- 16% x 1.0 = 162 trol or check plot): 17.2 bu./acre 38% - 16% = 22% increase

312

320 Data from a Maize Variety Test on 25 Yams

YIELD BENEFIT SQUARE OF Farm BENEFIT New Practice Control Bushels/acre Bushels/acre Bushels/acre

1 23 16 7 (7)2 49 2 2 37 26 11 (11) 121 2 3 24 17 7 (7) 49

4 20 14 6 (6)2 36 (5-21)

22 24 17 7 (7) 49

23 22 16 6 (6) 36 2 24 28 21 7 (7) 49

25 26 19 7 (7)2 .49

SUMS 591 429 162 1236 AVERAGES 23.6 17.2 6.5

How to Calculate the Standard Deviation: a. Sum of the squares of the benefit = 1236 bushels 2 2 b. (Sum of the benefits) (162) = 1050 bushels number of farms 25 c. Subract (b) from (a): 1236 - 1050 = 186 bushels d. The difference (c) 186 = 7.75 bushels Number of farms - 1 24 e. Standard deviation = square root of (d) or.177f 2.8 bushels f. Standard deviation (e) x 100 2.8 x 100 = 16% Average yield of the control 17.2 Therefore: 16% = the standard deviation (variation) as a percentage of thelaverage yield under the old practice (control).

313 c. What is the minimum Ratio Answer (percent) increase in yield that 2.6 Fewer than 0.5% farmers can expect three 2.3 1% out of four times? 2.0 2% 1.6 5% Solution: Multiply the 1.3 10% standard deviation as a 1.0 15% percentage (16%) by 0.7 0.8 20% a mathematical constant 0.7 25% used in statistics. Then subtract the result from the average increase in 7. Interpreting the Results on an yield expressed as a per- Economic Basis centage (38%). Solution using above data: Since most new practices in- 16% x 1.0 = 16% volve increased costs, the real 38%-- 16% = 22% increase test of their benefits is the In- d. What percent of the farm- crease in net returns over the in- eta are likely to get no crease in costs. The same statist- increase in yield from the new practice? ical' procedures used above can also Solution: Divide the be applied to the net. economic ben- average benefit by the efit and the cost/benefit ratio standard deviation to obtain A ratio. Then look tests. up the answer according to this ratio in the following table, interpolat- ing if needed.

Solution using above data:

6.5 bu. = 2.3 (ratio) 2.8 bu.

Answer = 1% of farmers

314

Ale

322 Appendix E t., How to Convert Small Plot Yields

When dealing with yields from Method 2: Make a propo tion field trials, demonstration plots, Area Yield 1 1 1 and farmers' fields, you will usually Area Yield 2 2 want to convert them to a kg/ha, 10000 s Y1 lbs./acre or other standard basis. 1200 sq. m 300 kg There are several easy ways to do To solve the propor on for Yi, .this, and they are best shown by cross multiply like this: example. 1200Yl = 300 kg X 40000.. Thensolve for Y1: PROBLEM 1: Pore harvests 300 kg of 1 300 kg X 10000 shelled maize off a field Y 1 1200 ) v measuring 30 X 40 meters. Y =2504kg/ha of What is her yield on a 1 maizefrimitPore's field kg/ha basis? SOLUTION PROBLEM 2: Lam harvests 150 lbs. of Method 1: 10000 sq. m (1 hectare) dried cowpea seed off a plot area in sq. m field measuring 45 X 75 plot yield yield in X = feet. What is his yield in kg kg/ha in terms ofbs. per acre? 10000 sq. m

1200 sq. in 300 kg SOLUTION 1\ 2500 kg/ha of maize Method 1: 43560 sq. ft. (1 acre) from Pore's field plot area in sq. ft.

315 323

/ plot yield yield in X = in lbs. lbs./acre 43560 sq. ft. X 150 lbs. 3375 sq. ft. = 1936 lbs./acre of cowpeas from Lam's plot 0 Method 2: Make a proportion Areal Yield 1 Areal Yield 2

I/ 43560 sq. ft. 1 3375 sq. ft. 150 lbs. Then cross multiply and solve for Y like this: 1 3375 Y = 150 lbs. X 43560 1 150 X 43560 Y = 1 3375 Y = 1936 lbs./acre of 1 cowpeas from Lam's plot NOTE: You can "mix" units of measure from different systems if you' know the conversions. Examples: I Acre = 400'sq. m 1 Manzana (Central America) = 1.73 acres = 0.7 ha = 7000 sq. m

316

324 Appendix F How to Take Soil Samples

I. Divide the Farm into Sampling cording to the above criteria. Units: Each sample sent to the Each sampling unit should contain lab is really.a composite sample only one type of soil (that is, do made up of 10-20 sub-samples taken not combine red soil with black from an area that is uniform in soil, hill soil with level soil, color, texture, topography, past fertilized soil with unfertilized management, and other characteris- soil, etc.). It is important to tics dint may influence soil fer- have.a good idea of the land's fertility. A farm may have several tilizer and liming history to avoid of these distinct areas which are. variations within one sampling unit. referred to as sampling units. The final map with numbered sampling Begin by drawing a map of the farm units might look like this land to be sampled. and then divide it into separate sampling units ac-

4:0 Rs.t. AoLi. \LoNED N Lk meo 4*.S A C.K IL. geol.rtiz #.4°izeRttl,.20/0

317

325 Size of sampling units: A sam- depth and be uniform in plingunif should usually not thickness. Holding the exceed 4-6 ha. Of course, small face of the soil slice with farmq will have much Smaller your hand will keep it sampling units. from crumbling apart. Scrape off any surface 2. For each sampling unit, collect litter before sampling. sub-samples for making a composite sample representing that Trim down the width of the unit. soil sample on the shovel With the machete until it If the farm has three sam- is about4-5 cm wide and then pling units, the farmer will dump it in a pail. send in three soil samples to the lab. Each sample will Sampling_guidelines: Do not consist 'bf 10-20 sub-samples take sub-samples from taken at random within the fertilizer bands, under sampling unit. animal droppings or along a fence line or extreme Depth of sampling:Most end df a field. Use a labs want topsoil samples thoroughly clean pail that only about 15-20 cm deep. has not been used to hold When sampling fields to be fertilizer. Galvanized used for pasture, a5 cm pails will make zinc tests depth is sometimes requested inaccurate. by the lab. Avoid_ including any subsoil in a topsoil Preparing a composite sample: sample unless the topsoil After collecting the 10-20 layer is very thin because random sub-samples within one of erosion. sampling unit, thoroughly mix them in the pail and then To take a sub - sample: A take out enough soil to fill shovel and a machete can be up tie soil sample box. used, although a soil auger is better when the ground is Guidelines: Never mix soil very hard. from different sampling units. to not oven dry wet samples, If using a shovel, make a because this will cause a hole with 450 sides to the falsely high potassium read- right depth and then care- ingin the test. Air dry fully dig out a slice about them instead. Clean out the 3-5 cm thick. The slice pail completely before mov- should extend to the appro- ing to another sampling unit. priate vertical sampling

318

32 Fill out the information sheet:The form from the soil laboratory will request information about the soils' slope, drainage, cropping history and yields, past applications of fertilizers and lime, crops to be grown*and desired yields.

When to take soil samples: Send them in at least two months before you need the results. In areas with a concentrated planting season, farmers tend to wait until the last minute to send in samples, and the lab is linable to process all of them on time.

How often is teting_needed? Under low to moderate rates of fertilizer use, a field should be sampled about 4 once every three to five years, since the soil's fertility level is unlikely to change significantly on a year-to- year basis. This is fine, since fir- mers with limited capital should con= centrateonteeding the present crop \ rather than building up the soil's general fertility level.

327

Jr I Appendix G Hunger Signs in the Reference crops

Legumes Nitrogen The lower leaves begin to 4, turn.light green and then yellow with .the. symptoms progressing gradually Maize, Sorghum, Millet upward. Plant growth is stunted. Young plants are 'stunted and spindly with yellowish-green leaves. In older plants, the tips of the Phosphorus lower leaves first show yellowing which progresses up the rgld-rib.in a "V" shaped pattern, while the leaf A margins remain green. In some cases, Maize, Sorghum, Millet

a general vellowina ofihe lower, Hunger signs are most likely ' -leaves occurs. In severe cases, the during early growth.Mild shortagei lower leaves soon turn brown and die usually e4use.stunting without clear . . from the tips down. (This "firing" leaf symptoms. More severe short - can also be caused by drought which cause a purplish color starting 7' Maize ears are prevents N uptake.) a the tips of thelower (older) 4 smnll_and pinched at the tips. leaves which may begin to turn brown and die. Some varieties of maize and ",..

_ sorghum- do not show a purplish color but rather a bronze coloration of the 321 same pattern. Disregard Purple stems. potassium-deficient plants are often In maize and sorghum, "symptoms small and may have pointed, poorly usually disappear once the plants seeded tips. reach 40-45 cm, but yields will be Legumes severely lowered. Maize ears from Potassium deficiency is seldom P.- deficient plants are somewhat seen in beans;, but can occur in highly 'twisted, have irregular seed rows, infertile soils or those high in and seedless tips. calcium and magnesium. Symptoms Legumes are yellowing and death of leaf tips Phosphorus hunger signs often and margins, beginning on the lower are not well defined. Plants lack leaves and gradually moving upwards. -vigor and have few side branches. Upper leaves become dark green, but remain small. Flowering and maturation are retarded. Calcium

Potassium Beans ./ /Calcium deficiency in beans is i uncommon, but most likely to occur fn combination with aluminum toxicity Maize. Sorghum, Millet in Very acid soils. Leaves stay green The three crops rarely show wigh a slight yellowing at the mar- symptoms the first several weeks of gins and tips. Leaves may pucker and growth. The margins of the lower curl downwards. leaves turn yellow and die, start- Peanuts ing at the tip. Potassium-deficient Light green plants withea plants have short internodes and weak: high percentage of "pops" (unfilled stalks. Maize stalks sliced length- pods) show symptoms of calcium

wise often reveal nodes that are a I' deficiency. darkigh I)rown. Maize (Is from 322 ;. 329 low S fertilizers have been used for Magnesium several years. Maize, Sorghum, Millet These crops have relatively lo0 S needs. Stunted growth, de- Maizet_lorghumi Millet layed maturity, and a general yellow- A generalyellowing of the Ira of the leaves (as distinguished

lower leaves is the first sign. Biren- from N deficiency) are the main signs. tually, the area between the veins Sometimes, the veins may stay green turns light yellowto almost white whichmay be mistaken for zinc or while the veins remain fairly green. iron deficiency. However, iron and As the deficiency progresses, the zinc hunger are more likely ih basic leaves turn reddish-purple along or only slightly acid soils. their edges and tips, starting at the Beans lower leaves and working upward. Upper leaves become uniformly Beans yellow. Most likely in acid soils or those high in Ca and K. Yellowing between the veins appears first on older leaves and then moves upward. Zinc Leaf tips show the first effects.

Zinc deficiencies occur where soil pH is above 6.8 and high rates of P are Sulfur used, especially if placed in a band or hole near the seeds. Maize Where to,adSpect: Sulfur deficiencies Maize shows the most clear- may be suspected where there are vol- cut zinc hunger signs of all crops. canic or acid, sandy soils. and where If severe, symptoms appear within two

323 330 weeks of emergence. Abroad band of crops show an interveinal yellowing bleached tissue on each side of the mid-that extends the full length of the ribs of the upper leaves, mainly on leaves and occurs mainly on the the lower part of the leaves, is upper leaves. typical. The mid-rib and leaf margin Legumes stay green, and the plants are stunted. Interveinal yellowing of the Mild shortages may cause a striping upper leaves.occurs. They eventually between the veins similar to manganese may turn uniformly yellow. or iron deficiency. However, in Fe and Mn shortages, this interveinal striping runs the full length of the leaf. Manganese Sorghum Similar to maize, but less interveinal striping, and the white Where to suspect: Manganese defici- band is more defined. encies are uncommon in maize, millet, Legumes or sorghum. It occurs in soils Interveinal yellowing of the which have a pH rf 6.8 or above and upper leaves. in sandy or heavily, leached soils. Peanuts Yellowing between the veins of the upper leaves which eventually Iron turn uniformly yellow and then bronze is a symptom. Beans Iron deficiencies can be suspected Plants are stunted. Upper where soil pH is above 6.8. leaves become yellow between the Maize. Sorghum. Millet small veins and eventually take on a Sorghum is much more prone to bronzed appearance. iron deficiency than- maize. All three

324

331 Manganese toxicity occurs on very acid severe cases, plants stay stunted soils 'and is accentuated by ,poor drain-and may die shortly after emergence. age. 'Beans are very susceptible. The Boron toxicity. can be caused by upper leaves show an interveinaliel- applying a fertilizer containing lowing. Easil3, confused with Zn or boron too close to the seed row or Mg deficiency, but Zn deficiency is by'applying B non-uniformly. Symp- very uncommon in highly acid soils. toms are yellowing and' dying along the leaf margins of the plants shortly after emergence. Boron

Where to suspect: Boron deficiencies can be suspected in acid, sandy soils or high pH soils. Beans and peanuts are the most susceptible of the reference crops. Peanuts Foliage may be normal, but kernels often have a hollowed out, brownish area -in the meat. This is usually referred to as "internal damage". Beans Thick stems and leaves with yellow and dead spots. If less severe, leaves are puckered and curl downward. Easily confused with leafhopper or virus at ack. In very

325 332 Appendix H Miscellaneous Pulses

Chickpeas nitrogen fixing ability. Uses and Nutritive Value Chickpeas are consumed as immature seeds (and pods) or as mature seeds. Also used as a Other names: Garbanzo, gram pea coffee substitute after roasting. Scientific name: Cicer arietum .. The seeds contain about 70 percefit Main areas of _production: 90% of the world's production occurs in protein. India and Pakistan, but chickpeas World chickpea production are also an important crop in Lebanon, Turkey, Syria, Iran, averaged around 7 million tons/year Bangladesh, Burma, Nepal, Colombia, during the 1975 -1977. period and was Argentina, and Chile. largely concentrated in India and Adaptation, Characteristics Pakistan. Chickpeas prefer cool, semi- arid conditions. The seeds have a very permeable coat and lose their viability (germination ability) quickly under high humidity. The crop has a very deep root system and is a very efficient extractor of soil phosphorus. It has good

327 3'33 Pigeonpeas Late varieties take about 9-12 months. Although the plants will grow for three to :our years, yields tend to decline. It is often best to treat it as an annual or to slash it back and Other names: 'Gandul take ratoon crops using the cut branches Scientific name: Cafanussajan and leaves as livestock feed. Main areas of production: India, the Caribbean (especially the Dominican Republic and Puerto Regional figures are not Rico). Colombia, Panama, Venezu- ela, the Middle East, and parts of available for pigeonpea production, Africa. but worldwide production probably Adaptation, Characteristics totals about half that of chickpeas. This is a woody, erect, short- Green pod yields range from lived perennial which can reach a about 1000-4000 kg/ha with up to height of three to four meters. Pods 8000 kg/ha possible. Yields of dry are pez, 1;ke and ;air) with three to seeds average about 600-1100 kg/ha, seven seeds. Seed color varies from but up to 2000 kg/ha is possible. white to red,or almost black.Plants The plants are very efficient can be used as a windbreak. Pigeonpeas nitrogen fixers. are very drought resistant and tolerate Nutritive Value and Uses a wide variety of soils and rainfall Both the dry seeds and the conditions. They are usually treated young green ones (sometimes with as an annual or biennial and prunted to the pods) are eaten. Mature dry encourage branching after each crop. seeds contain about 20 percent. They are often interplanted with maize, The dried stalks and branches are sorghum, millet, beans, and squash.. used for firewood, thatching, and Early varieties take 12-14 weeks until baskets. The crop is also valuable pod initiation and a total of five to as a forage, windbreak and green six months to maturity. manure (organic fertilizer) crop,

328

334 and for soil erosion control on ed in the mature form.. Limas are slopes. less drought-tolerant than many other legumes and are very-sensitive to soil acidity (the optimum Lima Beans pH is about 6-7). Varieties are either day neutral or shor -day in their response to day ength. Scientific name: Vining types have been g own up to Main areas' of production: One of elevations of 2400 m in', the topics. the most widely grown pulses in both temperate and tropical areas. Nutritive Value and Uses Lima beans are the main pulse crop Lima beans are grown mainly in the wet rainforest regions of tropical Africa and Latin America. for the dry, shelled beans, but the Extensively grown in Liberia, Burma, immature seeds are sometimes cooked and Nigeria. as a vegetable along with the pods Types and leaves. Some varieties have a Most breeding research has dangerous level of hydrocyanic acid focused on the erect, non-vining (HCN) in the leaj/es, pods, and bushy types with strong stems and a seeds, but this can be dissipated self-standing ability. However, by boiling and changing the cooking these bush varieties are not well water. Colorpd 'seed varieties are adapted to hot, humid conditions higher in HO than white ones. like the vining types of limas. i The ants also are used as Adaptation, Characteristics a green ntan rZ1e crop and as a cover The vining varieties require crop (to protect the soil from a support crop or other form of erosion). 'The seeds contain about staking. They tolerate wetter 20 percent protein i- the mature, weather during growth than cowpeas dry form. or common beans but need dry weather during the late stages when harvest-

329

335 Mung Beans Volunteers to introduce the soybean to their work areas. However, one should be aware of the following potential problems:

Other names: 'Golden gram, green gram Local pulses may be better adapted to the area. Soy- Scientific names: Phaseolus aureus beans do not tolerate soil Mung beans are an important acidity well and prefer a pH between 6.0 and 7.0. crop in India. China, and the High rainfall and humidity Philippines and have been introduced encourages diseases and into other areas. They are fairly insects. The crop is largely growt drought tolerant but susceptible to for export and for making poor drainage. They are eaten ao soybean oil and meal, the boiled mature seeds, green pods or latter used in livestock feed. sprouts. The crop is also used for Cooked soybeans often have forage, green manure or as a cover an unpleasant off-flavor or odor which can make them crop. Mung beans are efficient unpalatable to many people. nitrogen fixers. However, the University of Illinois has developed an inexpensive cooking method that solves this problem. Soybeans Peanuts have the advantage over soybeans of being both a cash crop and a food crop and are also more drought - Scientific name: Glycine max tolerant. The most extensive areas of As with some sorghums and soybean production are in the U.S., millets, soybeans are highly photosensitive to daylengto., Brazil, Argentina, China, and other and varieties have a very parts of Stout ±ast Asia, although narrow range of adaptation north and south of their the crop is ,;rown in many other oriO.ns. U.S. Corn Belt areas worldwide. Its reputation varieties are normalll grown under very long summer &Ls/- as a high protein, crop (35-40 per- lengths and if moved to short- cent protein) !las tempted many

330 336 day tropical areas, they and have some valuable characteris- become dwarfed and reach maturity much too quickly. tics: However, varieties are ,The dry seeds contain about available for tropics. 34 percent protein and 18 While soybeans are an extreme- percent oil which makes them ly efficient nitrogen fixer, about equal to soybeans. they require a unique type of The young leaves and pods Rhizobia bacteria unlikely to can be eaten too. be present in soils not pre- Some varieties produce edi- viously cropped to soybeans. ble tubers with a reputed In such cases, the seed needs protein content of 20 per- to be innoculated with a com- cent, although some investi- mercial stain of Rhizobium gators feel that this is japonicum. Soybean Rhizobia; considerably overestimated. are adversely affected by soil pH's much below 6.0. They are a very efficient nitrogen-fixing legume and produce good yields. Yields of up to 2500 kg/ha of mature dry seed have been reported. Winged Beans Now for some of the disadvantages of winged beans:

Scientific name: Phophocar2us The plants must be staked tetragonalobus or they will not flower well, although they can be grown Winged beans are not a iow protltrate for their tubers. crop, but have received much publi- The seeds must be cooked city as a possible "wonder crop." using a special technique and soften slowly in water. In the interest of clarification, The cooked, mature seeds some basic facts are presented here. have a strong flavor which is disliked by some. How- The plants are twining vines ever, they do not have po- that grow. to over three meters when tential for the making of cutds and tofu as with soy- supported and produce pods with four beans. The seeds have some longitudinal jagged "wings" that likely metabolic (digestive) inhibitors that have not contain up to 2U seeds. Winged been adequately investigated. beans are adapted to the wet tropics Introducing a new crop into

331

337 I an area is usually a task better left to professionals associated with a research station that has the money, time, skills, and dis cipline for such an undertaking. The extension workers' job is to provide the tested recommendations for the crops grown in an area.

332 338 Appendix I Troubleshooting Common Crop Problems

It takes a lot of practice crop variety, etc.). Note whether and detective work to accurately' the problem occurs unifomly over troubleshoot crop problems.Some the field or in patches. This can abnormalities like wilting or leaf provide valuable.clues, since some yellowing can have numerous causes. problems like nematodes and poor First, learn to distinguish drainage seldom affect the entire normal from abnormal growth when field. you walk through a farmer's field. Troubleshooting tools Keep a close watch for telltale A pocketknife for digging up trouble signs such as abnormal seeds or slicing plant stems to check for root and stem color, stunting, wilting, leaf spots, rots or insect borers. and signs of insect feeding.Make A shavel'or trowel for exam- a thorough examination of affected ining plant roots or checking for soil insects or plants, including the root system adequate moisture. and the inside of the stem, unless A pocket magnifying glass to the problem is obvious. Obtain facilitate identification of insects and diseases. detailed information from the A reliable soil pH test kit farmer concerning all management for checking both topsoil practices that might have a hearing and 'subsoil pH. Especially useful in areas of high soil on the problem (i.e. fertilizer and acidity. Beware of cheap pesticide applications, name of kitd, especially those using litmus paper. The Bellige- Truog kit is one of the best and costs about $15 U.S. 333 ti 339 Troubleshooting guide CROP APPEARANCE pROBABIE CAUSES

POOR SEEDLING Low-germination seed EMERGENCE Planting too deep or too shallow (Carefully dig up a Soil crusting or overly cloddy soil section of row and Lack of moisture look for the seeds) Clogged plabter Seeds washed out by heavy ra Fertilizer burn Pre-emergence damping-off deisease Birds, rodents Seed-eating insects (wir tms, seed 'corn maggots, seed corn beetl WILTING Actual lack of moisture/ ue to drought or (Pull up afew plants poor. irrigation manages nt (watering too carefully using a shovel lightly or too infreque tly) or trowel and examine Diseases (bacterial or fungal wilts, cer- the roots. Check stem tain types of rot and tem rots) for borers or rotted or Very high temperature,, especially if discolored tissue.) combined with dry, w dy conditions Root pruning by hoe o cultivator Nematodes (especially if confined to patches and when plan s wilt despite having sufficent war ) Stem breakage or kinking LEAF ROLLING OR CURLING Lack of moisture (=Lie, sorghum, millet) Virus Sucking insects feeding on stem or leaves Boron, calcium defiCiency (beans only) Verticillium wilt (peanuts) LEAF CRINKLING, PUCKERING Aphids, leafhoppers feeding on leaves orstems LEAF "BURNING" OR BROWNING Drought Excessive heat Fertilizer burn Insecticide overdose Dipterex, AzodrIn (Nuvacron), or methyl Parathion injury on sorghum Herbicide damage Nutrient deficiency Aluminum, iron, or manganese toxicity due to excessive acidity (below pH 5.5)

334

4'1 340 CROP APPEARANCE PROBABLE CAUSES ti Salinity or sodium problems (confined largely to low rainfall areas, especially if irrigated) Boron toxicity -from irrigation water .(low

. rainfall areas) of improper placement of fertilizer boron 4 LEGGY, SPINDLY PLANTS Lack of sunlight caused by"overcrowding or long periodS of heavy cloudiness

HOLES IN LEAVES Caterpillars t Beetles Earwigs Crickets Snails, slugs, especially \n beans (check for slime 'trails) Breakdown of dead tissue due to fungal or bacterial leafspots SPOTS ON LEAVES Fungal or bacterial leafspots Virus Sucking insects Spilling"bf fertilizer on leaves Herbicide spray drift, especially paraquat (Gramoxone) eunscald (beans) LEAF MALFORMATION WITH 2,4-D type herbicide damage due to spray STEM CURVING & TWISTING drift or a contaminated sprayer (broadleaf (Broadleft plants only) crops only) so LEAF MOTTLING, LEAF Virus MALFORMATION, PLANT MALFORMATION LEAF STRIPING Nutrient d4ficiency Virus Genetic YELLOWING, STUNTING Nutrient deficiency Poor drainage Nematodes Low pH (excessive acidity) Root rot, stem rot OVERNIGHT DEFOLIATION Leaf cutter ants, grazing animals OF PLANTS"

335

341 PROBABLE CAUSES CROP APPEARANCE PLANTS CUT OFF AT OR Cutworms Mole Crickets NEAR GROUND LEVEL 4' TWISTING TUNNELS INLEAVES Leaf miners bUghts COLLAPSE Fungal seedling YOUNG SrEDLINGS Heat girdling of stem(beans) NEAR GROUND LEVELAND DIE Too dry or toowet POOR GROWTH, LACKOF Too hot 'or toocold VIGOR Insects, diseases Weeds Unadapted variety a Low pH Salinity-alkalinity problems Overcrowding Shallow soil Soil compaction,hardpan Poor drainage Nutrient deficiency Faulty fertilizerpractices Nematodes._ excessivecloudiness Herbicide carryover Overallpoor management Damaged seed(beans) Overcrowding LODGING OR STALK Stalk rots BREAKAGE (Maize, Rootworms Sorghum, Millet) High wind K deficiency, correct type ofRhizobiaseed ON PEANUTS, Soil lacks the POOR NODULATION needed OTHER innoculation is COWPEAS, SOYBEANS; innoculation: wrong strain, EFFICIENT Improper LEGUMES THAT ARE innoculant too old orimproperly stored N FIXERS(Carefully dig up innoculated seed toexcessive and check Exposure of certain the root system .sunlight or contactwith fertilizer or clusters for nodulation; seed treatmentfungicides, of fleshynodules, espe- (soybegns are especially and Excessive acidity cially on the taproot, sensitive to soilpH's below 6.0) interiors are with reddish Molybdenum deficiency signs of goodnodulation. (it takes 2-3weeks . Plants are too young nodules for the nodulesto Don't confuse, after plant emergence with nematodegalls!) become visible)

-336 342 ti

40 Appendix J Guidelines for Using Pesticides

Pesticides are poisons and reproductive effects -.ef- fecting an individual's are used to kill particular plants capacity to bear young and animals that reduce the productivity of a farmer's crop. For- It is important that the tunately, however, many pesticides jarmer and 'extension worker bp a- have unwanted side effects and may ware of the level of toxicit of be hazardous to non-pest plants and the chemicals with which they are animals, including man. working and the following table Pesticide toxicity to ani- lists the relative acute toxicity mals may be acute, i.e., having of some commonly ,used pesticides. \ effects resulting in illness or The toxicity classes presented arg death, or it may be chronic,.i.e., based upon oral and dermal acute 1 having effects that may not be ap- toxicity to rats.

parent for many years. Chronic tox- class 1'1.most dangerous; requiringa label reading icity may take the following forms: "danger" oncogenicity - cancer-caus- class 2 less dangerous; ing requiringa label reading teratogerity - causing de- "warning" formities in offspring class 3 .=less dangerous; mutagenicity - causing gen- requiringa label reading

etic mutations . "caut ion"

1. Label renniremente established by 337 . - the U.S. Environmental Protection Agency (40 CFR & 162.10). 343 Please note that the toxicity clas- icide which is highly ses only refer to acute toxic ef-. toxic as a concentrate (Class 1) will still be fects and the chemical may be a dangerous when diluted to Class 3, least dangerous, and still the concentration at which it is useful. have serious potential long-term toxicity. 2. The LD50 ratings give little information on The acute toxicity is rated the cumulative.eff.gct accordingly to the dose of pesticide of repeated exposure. that is lethal to 50 percent of the 3. If'spilled on the skin, test animals that ingest it (oral liquid insecticides are more readily absorbed LD50) or absorbed through their skin than wettable powders (dermal LD50). The LD50 of a pest- or dusts. 40 icide is measured in milligrams of 4. Note that some insect- pure chemical per kiligrams of test icides like TEPP and Phosdrin are about as animal body weight (mg/kg). The toxic dermally as they lower the LD50,-the less chemical are orally. required to kill 50 percent of the 5. Even Class 3 (least test animals and thus, the higher. dangerous) insecticides like Malathion can cau- is the pesticide's toxicity. There se severe poisoning if are several important considerations enough is ingested or spilled on, the skin', in usin&the LD50 ratings. especially in the concentrated form.

1.,1The LD ratings are 50 -,;bised on the amounts of 100 percent strength from Pesticides include insecticides, one percent up to 95 per- fungicides, herbicides, nematicides tent. After dilution with water for spraying, and rodenticides. In general the her- actual strength may only lucides and fungicides are not in the be about 0.1-0.2 percent. As a general rule-a pest-

338 344 highly toxic categories (1 and 2) short residual lives. The OP's and whereas a fair number of the insect., C's break down fairly quickly, but, is ides and nematicides are very dan- also vary greatly in toxicity. geroUs to use. Insecticide Names: Note that each Table J-1 gives a partial Insecticide may be marketed under listing of insecticides, their der- several different trade names.Many mal and oral LD5os and the chemical extension bulletins refer to insec- group to which each insecticide be- ticides by their non-commercial chem- longs as follows: ical names (i.e. Sevin is a trade CH = chlorinated hydrocar- name for carbaryl). This can create bon, much confusion in indentifying in- OP = organic phosphate, C = carbamate, secticides. M = miscellaneous The following pesticides have The antidote for poisoning been suspended, canceled or with- varies with the chemical group. A- drawn United States and their use side from this difference, it's hard should not be encouraged in interna- to make meaningful distinctions be- tional agriculature projects: tween these chemical groups. For DDT Mirex DBCP Aldrin Chlordane 2,4,5-T example, Aldrin, DDT, Endrin,liepta- DieldrinHeptachlorBHC (benzene chlor, Lindane. and Kelthane (dico- hexochloride) Endrin TOK Amitroz fol) have long residual lives and Kepone Pirimicosb are all CH's. However, in terms ef gardona dimethoate, their immediate toxicity, they vary (dusts only) greatly - DDT is a Class 4 (least galecron* dangerous), while Endrin is a Class *Only can be4pplied under specialized handling'onditions on non-food I (most dangerous). Other CH's (cathon) crops Where mixer/loads like Methoxychlor have relatively exposure can becai'efully controlled.

339

345 Ilk

Table J-I Toxicity of Selected Insecticides Category I LD50 RatingChemical Common Name. Other Trade or Chemical Names Oral DermalGroup Dasanit 6 Terracur, fensulfothion 2-10 3-30 OP

Disyston 6 Disulfoton, Fruminal, oxydis'- 7 15 OP ulfoton Dyfonate 6 Fonofos 8 25 OP Endrin 2,5,6 Hexadrin I 18 CH Parathion 6 Ethyl parathion, Bladan, Niran, 13 21 OP E-605, Polidol E-605, Phoskil, Orthophos, Ekatox, Parathene, Panthion, Thiophos, Aikron

Phosdrin 6 mevinphos, Phosphene', Menite 6 5 OP Systc_i 6 demeton, Solvirex, Systemox, 6 14 OP Demox Telodrin isobenzan 5-30 5-30 CH TEPP 6 Tetron, Vapotone, Kilmite 40 2 OP Thimet 6 phorate, Rampart 2 6 OP Temik 6 aldicarb below5 Aldrin 2,5 Aldrite, Aldrosol, Drinox, Seed- 39 98 CH rin, Octalene Azodrin 6 Nuvacron, Monocron, monocrotophos 17 126 OP Bidrin 6 Ekafos, Carbicron 21 43 OP Birlane 6 chlorfenvinphos, Supona, Sape- 10-155 108 OP cron

2. Long residue lifq (3-10 years).,

3. Moderately long residue life (1-3 years).

4. High oral, low dermal (skin) toxicity.

5. Now banned or withdrawn from usein the U.S.

6. A restricted pesticide in the U.S.based uponits acute hazard to humans.

7. Chemicals now under EPA's Rebuttable Presumption against Registration (RPAR) process.

340

346 Table J-1 (continued)

LD50 RatingChemical Common Name Other Trade or Chemical Names Oral DermalGroup

Dieldrin 2,5, Alvit, Octalox, Dieldrite 46 90 CH Furadan 4 carbofuran, Curaterr (See be- 11 10,000 low for granules)

Gusathion 6 Guthion, Carfene, azinphosmethyl 12 220 OP\

Methyl Para- Folidol M, Parathion M, Nitrox, 14 67 'OP thion 6 Metron, Parapest, Dalf, Partron, 1 Phospherno

Lannate 6 Methomyl, Nudrin 17-24 1000 \

Monitor 6 Tamaron, methamidophos 21 118 OP \ Mocap 6 Jolt, Prophos, ethoprop 61 26 OP Thiodan endosulfan, Cyclodan, Malix, 43 130 CH Thimul, Thiodex

Trithion catbophenothion, Carrathion 30 54 OP Nemacur 6 phenamiphos, fenamiphos 8 72 Category II

BHC 2,5 benzene hexachloride, Hexachior, 600 CH Benzahex, Benzel, Soprocide, Dol, Dolmix, Hazafor, HCH Bux Bufenkarb, metalkamate 87 400 Chlordane Chlorkill, Orthochlor, Belt, As- 335 840 CH pon Ciodrin crotoxyphos -385 OP

Diaz inon Basudin, Spectracide, Diazol, 180 900 OP Gardentox, Sarolex Dibrom naled, Bromex 250 800 OP Dimethoate Cygon, Rogor, Perfekthion, Rox- 215 400 OP ion, De-Feud

DurThan chlorpyrifos, Lorsban 97-276 OP Dipterex Dylox, Klorfon, Danex, Trich- 180 2000 OP lorfon. Neguvon, Anthon, Bovi- nox. Proxol, Tugon, Trinex

341 347 Table J.1 (continued)

. 1D50 Rating Chemical. Common Name Other Trade or Chemical Names Oral DermalGroup \

Folimat methoate 50 700 OP Folithion Nuval, Agrothion, fenitrothion 500 1300 OP Hostathion triazaphos 80 1100 OP Heptachlor2,5Drinox H-34; Heptamul 100 195 CH Lebaycid Fenthion 200 1300 OP Lindane 2 Gamma BHC, Gammexane, Isotox, 88 1000 CH! 'ORO, Benesan, Lindagam, Lintox, Novigam,'Silvanol Metasystox oxydemetonmethyl 47 173 OP Mirex 5 dechlorane 300 800 -GH Toxaphene3,7 Motox, Strobane T, Toxakil, Mag- 90 1075 ;CH num 44 Unden Baygon, Suncide, Senoran, Blat- 100 1000 C tanex, PHC, porpoxur

Vapona DDVP, dichlorvos, Nuvah, Phosvit 90 107'/ OP

Category III

DDT 2,5 Anofex, Genitox, Gesarol, Neocid, 113 2510 CH etc. Galecron chlordimeform, Fundal 127-372 3000 OP Gardona 5 Appex, Rabon 4000 5000 OP Kelthane 3 dicofol, Acarin, Mitigan 1100 1230 CH Malathion Cythion, Unithion, Emmatos, Fy- 1375 4444 OP fanon, Malaspray, Malamar, Zithiol Meihoxychlor Marlate 5000 6000 OP Morestan Forstan 1800 2000+ Orthene Acephate, Ortran 866 OP Sevin carbaryl, Vetox, Ravyon, Tricar-850 4000 C nant

Ted ion Tetradifon 14,700 10,000 CH Volaton phoxim, Valexon 1845 1000+ OP Actellic pirimiphos-methyl, Blex, Silosan 2080 2000+ OP

342

p 348 The following pesticides Pesticides presently under have been restricted for use in the RPAR review include the following: United States, based on human hazard, Beronyl EBDC's, including Mane!), mancozeb, metiram, nodam, and their use should not be encour- zireb, amobam aged in international smallfarmers' Cadmium Ethylene dibromide agricultural projects: Captan Ethylene oxide Diallate Inosyohk Arsenicals methyl paralthionmethamidophos Lindane ethyl paralthion methomyl (lannote) Maleic iydrozide tamaron (monitor) Sulfate parathion carbofubon (ex- Toxaphene cept granular Trifnralin formulations) dyfonate General Information on Common Insect- tr ithion icides

The following pesticides ar4 I Bacillus Thuringiensis being investigated by the U.S. En- A biological insecticide made vironmental Protection Agency under from a natural bacteria that kills the Rebuttable Presumption Against only certain types of caterpillars; Registration (RPAR) Program. These most effective against cabbage loop- pesticides have possible risks ers but also against hornworms (Pro- in the following five areas, but toparce) and earworms (Heliothis). the risks have not been proven and they Non-toxic to humans and animals. In- are therefore still Permitted for use: sects don't die immediately but stop 1. Acute toxicity; feeding within a few hours - it may 2. Chronic toxicity includ- take a few days for them to die. Ap- ing oncogenic and muta- genic effects; ply before the caterpillars are large 3. Other chronic effects; for best results. Needs no sticker- 4. Effects on wildlife; and spreader for most formulations.,o Com- 5. Lack of emergency treat- patible with most other pesticides. ment. Don't store the diluted spray for more

343 349 than 12 hours. Dosage'varies widely A, systemic insecticide of with the particular formulation. moderate toxicity to humans (Class II Diazinon (Basudin, Diazol, etc.) 2). Specifically for sucking in- Fairly broad-spectrum includ- sects (aphids, leaf hoppers, thrips, ing control cif many soil insects but stinkbugs, mites, etc.) and leaf not as effective on beetles (except miners. Should provide control fo.r for the Mexican bean beetle). High- 10-14 days: Don't apply within 14- ly toxic to bees. 21 days of harvest. Highly toxic to bees Above-ground insect control: 4cc/ with a.onen to two-day residual effect. liter of Diazinon 25 percent EC or General dosages for the three most com- Basudin 40 percent WP. mon formulations (all emulsifiable Dimethoate (Perfekthio4 Cygontl concentrates are given below): Rogor etc.)

Formulation of dimethoate Dosage-cc/100 liters

200 grams active ingred./liter 100-200 400 grams a.i./liter 50-100 500 grams a.i./liter 50-75*.

344

I 350 Dipterex.(trichlorfon, Dyloxl; Danex1,1 usually applied to the soil either Klorfonit etc.) in the seed furrow or in a band cen- Provides fairly broad spec- tered over the crop row; furadan trum insect control but not as effec- kills soil nematodes and soil in- tive on aphids, mites And thrips. sects but is also absorbed by the Dipterex causes severe injury when roots and translocated throughout applied to sorghum. Low to high tox- the plant where it controls sucking icity for humans. insects, stem borers, and leaf feed- General above- ground insect control: ing beetles and caterpillars for up 125-250 cc (100-200 grams) of Dipter- to 30-40 days. Band treatments are ex per 100 liters of water or 5-10 recommended for root feeding, soil CC. insects, while seed furrow applica- Armyworms or earworms feeding in the tions can be used for foliar insects. leaf whorl or maize: Dipterex 2.5 per- Furadan can also be band applied cent granules give longer control than during the growing season if it is sprays; apply a pinch in each whorl cultivated into the soil or can be which works out to about 10-15 kg/ha applied to the leaf whorl of maize. .1 (lbs./acre) of granules. 100 cc of May cause minor foliar injury to the granules weigh about 60 g. peanuts; do not place in,contact Furadan (Carbofuran) with sorghum or bean seed.,

A systemic insecticide-nemat- Kelthafie (dicofol, Acarin, Mitigan, Garbax) ocide available in 3 granular formulations (3 percent, 5 percent, 10 per- ,Kills mites only; not harm- cent) and as a wettable powder. The ful to beneficial insects. Gives wettable powder formulation is consid- good initial control of mites and ered too toxic for normal use, however; has good residual activity against the pure strength chemical has an them; non-systemic. Spray under- extremely high oral but very low der- sides of leaves. Don't feed crop mal toxicity. Furadan granules are residues to dairy or slaughter ani-

345

351 treatment is effective approximately -don't apply within seven, days of four months. slaughter. Sevin (carbaryl,Vetox, Ravyon, etc.) Volaton (Valexon, phoxim) Broad-spectrum insect control A less toxic and persistent except for aphids and mites.Very replacement for Aldrin for soil in- low toxicity for humans (Class 3). sect control. 'Low toxicity for hu- Very toxic to bees with a 7-12 day mans. Also available as a liquid residual effect. formulation for leaf insects. General dosage for Sevin: Use the General dosage for Volaton:Use

50 percent WP at 8-16 ce per/l. Use the 2.5 percent granules at 60 kg/ha for 80 percent WP at 5-10 cc/1 or 1.25- furrow application and 120 kg ha 2.5 tablespoons/gallon. Can be applied for broadcast application. Work into right up to harvest time on the ref- the top 5-7.5 cm of soil. erence crops. Fungicides: Except for mercury- Household dosages: For cockroaches based fungicides used for seed treat- and ants, use as a 2.5 percent strengthment like Agallol, Semesan, and Cer- spray (active ingredient basis); esan, fungicides pose little hazard this equals about 100 cc of Sevin 80 to health. Their oral toxicity'is wp per liter of water; don't use comparatively low, and there is lit- more than twice a week. tle danger of dermal absorption. Ticks, lice, fleas, horn flies on Some may cause allergies in sensi- beef cattle, horses, swine: Use 20cc tive people through skin contact Sevin 80 percent WP per liter of water. and can be eye irritants as well. Don't apply within five days of slaughter. Mites, lice, fleas on poultry: Use at same rate as for beef cattle and apply about 4 liters per 100 birds;

346 352 mals. Low toxicity (Class 3). two hours' residual effect; wettable General dosage: Use the 35 percent powder formulations are highly tox- WP formulation at four to five cc per ic but have leis than one day's residual

liter of water. . Use the 18.5 percent -effect on bees. EC at 1.5cc per liter of water. General dosage for Malathion: Four to Lebaycid (Fenthion, Baytex, Baycid) fivecc of Malathion 50 percent or 57 A relatively low toxicity percent EC per liter of water.Use Mala- (Class 2) organic phosphate for thion 25 pecent WP at 12 cc/liter. chewing and sucking insects, includ- Using Malathion for Control of Stored Grain Insects ing mites. Don't spray plants when temperatures exceed 320C.Very tox- Grain which is to be held in ic to bees with two to three days' storage should be protected from residual activity. stored grain insects. An approved General dosage for Lebaycid: Use grain protectant applied to the Lebaycid 40 percent WP at1.5-2 g per grain at time of storage will help liter of water; use Lebaycid 50 per- prevent an early infestation.Pre- cent EC atl-1.5 cc/liter of water. mium grade Malathion is the only Malathion (Cythion, Unithion, Male protectant available. Malathion spray) can be applied as a dust or spray A broad-spectrum insecticide at the following rates: of low human toxicity (Clss 3). 1. One percent dust on wheat flour at the rate of. Not as effective on armyworms, ear- 60 lbs. per 1000 bushels . worms, and flea beetles. Its resid- of grain. 2. One pint of 57 percent (five ual activity is decreased if mixed pounds/gallon) EC in three with water above pH 8.0. to five gallons of water per 1000 bushels of grain. Can be mixed with other pesticides except Bordeau and lime sul-

fur. Liquid formulations are moder- Apply the material to the grain as ately toxic to bees with less than it is placed in the bin. This

.347 353 Table SOME INSECTICIDE RECOMMENDATIONS FOR SPECIFIC INSECTS ATTACKING THE REFERENCECROPS1

AMOUNT OF ACTIVE CROP AND PEST INSECTICIDE INGREDIENT NEEDED REMARKS AND PRECAUTIONS

MAIZE kg/ha .

Cutworms carbaryl 1.7-2.25 Recipes for cutworm baits are given.

.., . .

1 trichlorfon 0.9-1.1 Direct spray at base of plants; use trichlorfon on sails high in organic matter. chlorpyrifos 1.1-2.25 Baits will give better control. Use higher rates Of chlorpyrifos for heavy infestations; don't apply chlorpyrifos within 50 days of harvest. Granules should be applied in an 18 cm wide band over the row at planting.

Rootworms Diazinon i1.1 Use Diazinon as a post-mergence basal spray / (Diabrotica treatment applied in a band over the row sPP.) when symptoms appear.

carbofuran , 0.85-1.1 Apply Furadan granules in an 18 cm wide band centered over the row at planting or in the

....?_ 0 seed furrow.

. . Wireworms carbofuran 1.1-2.25 Apply in seed furrow or in an 18 cm wide band

= over the row at planting; may not be effective in dry weather.

-Diazinon 2.25 Broadcast over /entire soil surface and work into the top p cm 1-2 weeks before planting

I .

1. These re4es are based on the latest information (1978-80) from the U.S. Dept. of Agris., North Carolina State Unfiiiiiiy, CleMson University (South Caron"), and CIAT.

354 355 CROP AND PEST INSECTICIDE AMOUNT OF ACTIVE REMARKS AND PRECAUTIONS MAIZE, cont. INGREDIENT NEEDED kg/ha

Seed corn beet- Diazinon . mix dust or WP Handle treated seed with rubber gloves. les, seed corn wireworms seed at the rate Other products like Lindane can be used. maggots, attack- Lindane may, of 15 grams ac- ing seeds also be used true ingredient - (see label per 10 kg of seed. for dosage) -.

. , White grubs see wireworms see wireworms Don't useinore than 1.1 kg/ha active ingre- (Phyllophaga) client Furadan if white grubs arethe only problem.

AphidS, maize Malathion 0.9-1.2 leaf (Rhopalo- siphum)

, Caterpillars Garbaryl 1.7-2.25 Direct spray into whorl; use lower rate on

feedinging in the . young maize.

. leaf whorl Malathion '. 1.4 1irect spray into whorl. (Spodoptera, Heltiothis, trichlorfon 1.12 Direct spray into whorl or use Dipterex 2:5% etc.) granules at 10-15 kg/ha (about a pinch per

whorl). ,

Flea Beetles carbaryl 1.1 35 Diaz ioon 0.55 35 , C P AND PEST . INSECTICIDE AMOUNT OF ACTIVE REMARKS AND PRECAUTIONS MA INGREDIENT NEEDED kg/ha

Maize rootworm carbaryl 1.1 Apply when there are 5 or more beetles feed- beetles (Dia- ing on the silks of each ear. Direct spray brotica spp.) at the silks .. Diazinon 1.1

Malathion 1.1

Stem borers Various non See caterpillars Most non-systemics will control stemborers (Diatraea, Zee- systemics like if applied between hatching and stem entry; diatraea, Bus- carbaryl, Dip- timing is critical; spray the leaf whorl. seola, Sesamia, terex, Pura- Furadan granules can also be'used in the.

Chilo, Eldana) dan. - whorl or at planting; check local .recommen- - dations.

Lesser corn- carbaryl Use general dos- Spray base of plants so that both stalk base stalk borer trichlorfon age rates given and nearby soil are covered. (Elasmopalpu in previous sec- lignosellus) tion.-

SORGHUM . Aphids Malathion 0.55-0.9 Do not use Dipterex or methyl parathion since they injure sorghum. dimetboate 0.25-0.37

Diazinon 0.28

Earworms or carbaryl 1.7-2.25 Begin application when there is one medium armyworms to large caterpillar per head. Don't ap- feeding on ply within 3 weeks of harvest. the-heads

359 358 CROP AND PEST INSECTICIDE AMOUNT OF ACTIVE REMARKS AND PRECAUTIONS .,- t, i SORGHUM, cont. INGREDIENT 'NEEDED kg/ha

Sorghum midge carbaryl 1.4-1.8 Wait until 30-50% of heads have begun to

(Contarinia . bloom; begin spraying if two or more adult midges sorghicola) Diazinon 0.28 are found per head; timing is critical; r=-" peat in 3-5 days where adults still exceed two per head.

Sorghum shoot See remarks -- -- Seek local recommendations; Furadan may be fly (Arheri- used at planting but should not touch rhe seed Bona) -

MILLET Refer to sorghum and maize

PEANUTS Rootworms Diazinon 2.25-3.3 Apply in a band 40-50 cm wide centered over (Diabrotica) the row just prior to pegging and work into top 5-7.5 cm of soil.

White grubs or Diazinon 2.25 Broadcast before planting and work into the wireworms top 7.5-10 cm of soil.

Thrips, leaf- carbofuran 1.1 Apply in the seed furrow at planting; reduce hoppers, aphids dosage by 256 on sandy soils, especially wireworms, at where runner varieties are used. Furadan is 361 planting treat- , highly toxic orally. 366ent PROP ANDTEST INSECTICIDE AMOUNT OF ACTIVE REMARKS AND PRECAUTIONS '' PEANUTS, cont. INGREDIENT NEEDED kg /ha

Lesser corn- Diazinon 2.25 Apply the granules in a band 40-45 cm wide stalk borer granules over the row; Don't apply unless damaged (Elasmopalpus plants exceed 10% before blooming"or 15% lignosellus) after; don't use plants for forage within 7 days or for hay within 21 days.

Caterpillars . carbaryl 1.4-1.8 Peanuts are quite tolerant of leaf loss; don't on leaves apply unless there are 12 or more caterpillars per meter of row length; apply while they are still small. Don't feed Toxaphene treated

. plants to dairy animals or to those being finished for slaughter. i

C4 Leafhoppers carbaryl 1.1-1.4 May be applied up until harvest.

Methoxychlor 1.1 Don't feed Methoxychlor treated plants for 10 days.

Thrips carbaryl 1.1-1.7 Can be applied up to harvest

, - Malathion 0.9-1.1 Don't feed plants for 30 days.

1.7-2.25 Don't feed plants to dairy animals or those being finished for slaughter.

Mites Sulfur dust 17-23 Apply to undersides of leaves once a week; also controls leaf spot deseilse (Cercospora).

363 362 1

CROP AND PEST 4 INSECTICIDES AMOUNT Of ACTIVE REMARKS AND PRECAUTIONS -,..,r, t.. 1.. BEANS INGREDIENT NEEDED kg/ha

25 kg of bait/ha For bait recipes, refer to the start of unit Cutworms Baits 1 IX, this section. 0.

trichlorfon 1.1 Spray base of plants and nearby soil.

White grubs, carbofuran 0.9 Apply in an 18 cm wide band over the row or wireworms in the furrow but not in direct contact with the seed; Fura4an has very high oral toxicity

. Diazinon 3.3-4.5 Broadcast over entire soil surface and worked into top 10 cm before planting.

1.7 Banded over the row and worked into the top

10 cm before planting. o.

Aphids Diazinon 0.55-0.85

Malathion. 1.4

naled 1.1

Bean leaf carbaryl 1.1-1.25 ' Use the lower rates on the bean leaf beetle. beetle (Cero- tome) and Dia-, Malathion 1.4 brotica beetles Methoxychlor 1.1-3.3 1 365 , 0.44 364. , ' Diazinon f ;

CROP AND PEST INSECTICIDE-- AMOUNT OF ACTVIE/ REMARKS AND PRECAUTIONS MANS, cont. INGREDIENT NEEDED kg /'ha S

. \

Bean pod'wee- carbaryl. 2.25 . Apply 6 days after flower initiation'and then:!- vil (Apion one week later. .. godmani)

(granular) i Methoxychlor A.1.7 1 . . ,

endosulfan 0.55-1.1 . .

Earworms carbaryl 1.7-2.25 (Heliothis spp.) Methoxychlor 1.1-3.3

Leafhoppers , carbaryl 1.1-1.7

Malathion 1.1-2.0

, Methoxychlor 1.1-3.3

naled 1.1

carbofuran 0.7-1.0 .Apply under the seed but not in direct con- - tact; carbofuran has a very high oral toxicity

14 control lasts 30-40 days.

Lesser corn- Diazinon 1.1-2.25 Spray in a band 15 cm wide over the row to stalk borer cover base of stems and nearby soil. (Elasmvalpus- lignosellus) trichlorf on 1.1

361 ass / /

CROP AND PEST INSECTICIDE AMOU T OF ACTIVE REMARKS/ANDPRECAUTIONS

BEANS, cont. ING EpIENT NEEDED t ktilit

Mexican bean carbar.yl /6.55 -1.1 , beetle (Epi- / ,- lachna) -1 acephate 0.75 Don't apply ace hate within 14 days of bar- vest. fe endosulfan 1.1 Don't apply w hin 3 days of harvest.

Malathion 1.35

Diazinon 0.55-0.85

Methoxychlor . 1.1-3.3 .

, Mites Kelthane 0.55-0.66 Don't apply dicofol within 7 days of harvest. . dimethoate 0.28-0.56

, 4

Slugs, Snai s Metaldehyde, 25 kg of bait . carbaryl r per hectare

trichlorf n ,

Stinkbugs carbary 2.25 e (Nezara spp.) naiad 1.7 Don't apply within 4 days of hatvest.

1 . / endosu fan 1.1 Don't apply ulthin 3 days of harvest. ,- 369 /

Bee Poisoning Hazard of Pesticides O Use insecticides of relatively low toxicity and Most bee poisoning occurs residual effect for bees. when insecticides are applied during Plug up or cover the hive the crop's flowering period. Spray entrances the night before spraying and then re- ----drift is another hazard. To avoid open them once the resid- bee kill: ual effect is over. Do not apply insecticides None of the fungicides is Cox- toxic to bees when crops is to bees. the same is true with are flowerin.l. Insect- icides applied as a dust most herbicides, although Gesaprim are.the most harmful to (hAtrex; Atrazine) and the 2,4-D bee*. herbicides are low to moderate in Do not dump unused quan- _ __titles of dust:, sprays toxicity. where they might become a Here is a partial guide to bee hazard. Bees will sometimes collect any the relative toxicity of Various type of fine dust when insecticides for bees. Note the

pollen is scarce. . differences' in residual effect.

WHEN APPLIED AS A SPRAY Insecticide Toxicity to Bees Residual Effect Aldrin .Very high. Several days tDiazinon High One day Dipterex Low to High 2-5 hours Lebaycid Very high 2-3 days Kelthane (.dicofol) Low Methyl parathion High ?Ass than.one day

Malathion . ,Moderate (liquid) Less than 2 hours 'High (wettable powder) Less than one day Metasystox Moderate None Dimethoate Very High 1-2 days Sevin Moderate to High 7-12 days

356 I Insecticide Safety Guidelines veloping countries commonly recommend Class 1. Read and follow label ' 1 and. Class 2 products. instructions: If the

label is vague, try and . if using Class 2 insec- obtain a descriptive ticides, wear rubber pamphlet. Not-all-in gloves and a suitable.

secticides can be applied ' respirator (good ones to all crops. In- cost $15-$25), as well appropriate use can dam- as long pants and a lone- age plants or result in sleeve shirt; wearrub- undesirable residues. ber boots if using a The label should state backpack sprayer. This the minimum allowable clothing should be wash- interval between applica- ed separately from other ton and harvest. garments. 2. Never buy insecticides 5. Do not handle plants that come in unlabeled within five days after bottles or bags; you may treatment with a Class not be buying what you 1 insecticide or with think. This is a seri- Gusathion (Guthion). ous problem in-develop- Do not handle plants within ing countries where one day of using methyl small farmers often.pur- parathion. chase insecticides in 6. Class 1 and 2 insect- Coke bottles, etc. icides are likely to be 3. When working with farm- especially common in. ers, especially those tobacco and cotton using backpack sprayers growing areas. instead of tractor spray- 7. Do not smoke or eat ers, NEVER use or recom- ' while applying pest- mend those insecticides icides. Wash up well in toxicity.Class afterwards. Their Safe use requires extraordinary precau- 8. Repair all leaking hoses tions and safety devices and connections before (gloves, special respi- using a sprayer.` rators, protective clothing. etc.). When- 9. Prepare insecticide solu- ever possible, avoid us- tions in a well-ventilated ing Class 2 products. 'place, preferably out- Unfortunately, extension doors. pamphlets in many der 10. Never' spray or dust on very windy days or against a breeze.

357 37.1 11. Notify beekeepers the 18, Make sure that you and day before spraying. your client farmers are familiar with the symp- 12. Insecticide poisoning toms of insecticide hazards increase in hot poisoning and the first weather. aid procedures given be- 13. Store insecticides out low.. of reach of children and away from food and liv- Symptoms of Insecticide Poisoning ing quarters. Store Organic Phosphates 6.Carbamates them in their original (Parathion, Halattion, Sevin, etc.) labeled containers which should be tightly seal- Both groups affect mammals ed. by inhibiting the body's production 14. Leftover spray mixtures of the enzyme cholinesterase which should be poured into a regulates the involuntary nervous hole dug in the ground well away from streams system (breathing, urinary and bow- and wells. el control, and muscle movements). 15. to not contaminate ste4Ms Dizziness, head- or other water sources Initial Symptoms: ache, nausea, with insecticidei,either vomiting, tight- duririg application or ness of the chest, when cleaning excessive sweat- equipment. ing. These are 16. Make sure insecticide followeci,or ac- containers are never companied by blur- put to any other use. ring of vision, Burn sacks and plastic diarrhea, water- containers (don't breath ing of the eyes,

the smoke). Punch . excessive saliva- . holes in,metal ones and tion, muscle bury them. twitching, and men- tal confusion. 17. Make sure.that farmers Tiny (pihpoint) are well aware of safe- pupils are an- .ty precautions. It is other sign. -. important that they un- detaLasid .tliat insect:- Late Symptoms: Fluid in chest, con- cides vary ftreativ in vulsion, coma, loss their toxicity. or urinary or bowel control, loss of breathing.'

358 372 Note: Repeated exposure to these of Ipecac) may be more organic phosphite and carbamate ineffective; This should be followed by 30 grams. secticides may increase susceptihil (1 oz.) of activated ity to poisoning by gradually lower- charcoal* dissolved in water to help absorb the ingthebody's cholinesterase level remaining insecticide from the intestines. without producing symptoms. This is 3. Get the patient to a a temporary condition. Commerical* doctor as soon as pos- insecticide applicators in the U.S. sible. Bring along the insecticide label.. usually have their cholinesterase 4. In the meantime; make levels routinely monitorol. the patient lie-down Symptoms of Chlorinated Hydrocarbon and keep warm. Poisoning Endrin, Chlor 5. If excessive amounts are dane, Dieldrin, etc.) Spilled,on the skin (es-. Apprehension; dizziness, hy- pecially in the cOricen- trate form), immediately per-excitability, headache, fatigue, remove clothing and bathe and convulsions. Oral ingestion may the skin in generous a- mounts of water and.soap. cause convulsions and-tremors as the 6: If the.eyes have been con- first symptoms. taminated by dusts or sprays, flush them im- First Aid Measures 0 mediately for at least 1. In severe poisoning, five minutes with copi- breathing may stop, ous amounts of water. which makes mouth to Insecticide absorption mouth resuscitation the through the eyes is very first priority. Use rapid. full CPR if the heart has stopped. Antidotes 2. If the insecticide has Whenever-possible, antidotes been swallowed and the should be given only under medical patient has not vomited, induce vomiting by giv- supervision. Too much or too little ing a of salt diesolVed in half a' *Activated charcoal is made by heat- glass of warm water. An ing charcoal to drive off its Absorbed emetic like EBesis (syrup gasses.

359 $ Appendix K Guidelines for Applying Herbicides With Sprayers v

The farmer should calibrate his/ The Principles her sprayer when a pesticide needs Involved to be applied at an accurate dosage in order to avoid applying'too much, *When a pesticide recommendation is given in terms of kg/ha or lbs./ which wastes money and might makel: acre of active ingredient or actual the product ineffective. When work- product, the'fari needs to know two things before he/she can apply the ing with small fields, farmers can correct dosage: usually use generalized recommenda-, The amount of pesticide needed tions given in cc/liter or table- for his/her particular field. spoons /gallonfor insecticides and The amount of water needed to convey the pesticide to the However, most most fungicides. plants or soil and give herbicides require more accurate adequate coverage. application, which means that Once these are know, it is a simple matter of mixing the correct sprayer calibration is usually amounts of water and pesticide needed. together, then spraying.

361 374 powder are needed per hectare and Calibration of the farmer's field is 600 square feet, ' this' would mean that 240 1 of insecticide Backpack Sprayers are required. Here's how we worked it out: 600.sq. m = X 10,000 sq. m 4O 0 NOTE: Only backpack sprayers with continous pumping action should be X = 240 used when calibrationois needed; Step 5: Divide the amount of pesti-. compression type sprayers (the garden cide needed. for the field bydthe variety that needs to be set down number of- sprayer tankfuls of water to be pumped up) are not suitable to determine how much pesticide is because of their uneven pressure. needed per tankful: Stop 1: Fill the sprayer with three 240 g Sevin 50% WP = 120 g Sevin/ to four liters of water and begin 2 tankfuls tankful spraying the soil or crop using the NOTE: A sprayer should be recalibrat- 'same speed, coverage and pressure that ed each time it is used on a. will be used in applying the pesiticide. different crop, different Heasure of this stage of crop growth or when .rti1:3e7t7hT:v7r:et !sevLaInt another pesticide is used. times to determine the average area sprayed. You can measure the area in terms of squre feet or in terms of Alternate Method row length. Using Row Length Step 2: Based on the area covered, you can calculate the amount of water needed to cover the field. When a pesticide is to be For example, ifthree liters covered applied to a crop grown in rows, 60 square feet, and the field measures 20 N 30 feet, it would take 30 liters ,you can use row length inslead of of water to cover theCield. area as the basis for calibratidn.

Ftep 3: Determine-tba_ammter of PROBLEM: Label instructions advise sprayer tankfdls of water needed tO Juan to apply Malathion 50 percent cover the field. For example, if the liacWonck sprayer holds' 15 1, it strength liquid at the rate of 4 1/ha. will take two tankfuls to cover the His field measures 40 x 50 m and the field. bean rows are spaced SO cm apart. Step 4: Determine how much actual pesticide is needed fur the field. His backpack sprayer hold 15 1, and IL 4 kg of Sevin 50 percent wettable

362: IS 375 he needs to know how much Malathion 2000 sq. vl = X 1 Malathion should be added to each tankful. 10,000 sq. m 4 1 Malathion SOLU1'iON X = 0.8 1 or 800 cc of Malathion needed 1; Follow the same procedure as with Step 1 of the first method 5. Find out how much Malathion is but measure the amount of row needed per sprayer tankful length covered by the 3-4 1 based on a capacity of 15 1. instead .of area. Suppose that '50 1 of water needed = 3:33 Juan was able to cover 150 m 15 1 tank capacity of row length with 3 1. tankfuls needed 2. Find out how many meters of row 800 cc Malathion = 240 cc of length his field has. Let's 3.33 tankfuls Malathion say the crop rows are running the long way (i.e. '50 m). 50%,liquid needed per Number of tows x 50 m = field's- sprayer

. total row length tankful Numberof rows = 40 m 0.8 m (i.e. the field's width) (80 cm) Calibration of 50 rows x 50 m = 2500 m of row length in Juan's field Tractor Sprayers 3. Find out how much water will be needed to cover the 2500 m of row length based on 3 1 per each 150 m Things To Do Before Calibrating a 150 m = 3 1 2500 m X 1 Sprayer 150 X = 7500 Rinse out the tank and refill X - 50 1 of water needed it with clean water. to cover the, field Remove. and clean nozzles 4. Find out how much Malathion and screens. Use an old 50 percent liquid will be toothbrush. needed for the field based on 4 1 of the pesticide per Start the sprayer and flush hectare (10,000 sq. m). Since the hoses and boom with plenty Juan's field measures 40 x 50m,' of clean water. its area is 2000 sq. m. Replace screens and nozzles and

363 376 make sure that they are of the minute. To do this, se a jar correct spray pattern type and to measure the individual size. output of several nozzles, Check all connections for-leaks. calculate the average, and then multiply this by the Adjust the pressure regulator number of nozzles to get the to the correct pressure with total output. the tractor engine running at field operating speed and with 3. Measure the width of coverage a of the spray boom in meters. the nozzles running. Do this by multiplying the

1 Check the water output of each (:umber of nozzles on the boom nozzle and replace any that are by their spacing in centimeters 15 percent above or below the and then divide by 100 to obtain avirage. the total-width in meters.

Remember to 4. Use this formula to deter 'e how many liters of water a, Calibrate the sprayer using the needed per hectare: same tractor speed and spray pressure that will be used to Liter/hectare = 10,000 x output of apply the pesticide. tractor speed in m/min. ° When using water to calibrate, spray boom in l/m the spray rate of-the water may x boom width in m differ somewhat from that of the Once you know the volume of water actual pesticide-water solution needed per acre or hectare, you can due to differences in density determine how much pesticide needs and viscosity. to be added per tankful of water by using the same procedure as given for backpack sprayers. Adjusting Sprayer Output Calibration Method If the water output is too low or

1. Drive tho tractor atfie ld too high per hectare, change nozzle operating speed in the appropriate gear and measure the sizes or tractor. speed. Changing the distance covered in terms of spraying pressure is relatively meters per minute (1 k.p.h. = 16.7 m per minute) ineffective and may distort the spray

2. Operate the sprayer at the pattern or cause excessive 'drift. correct pressure with the Pressure must be increased four-fold tractor stationary, and measure the totaloutput of in order to double output..i the spray bout ia liters per 4

364 c 41

water and spray a few sensitive How to plants (tomatoes, beans, cotton, etc.). If injury signs are.not Clean Sprayers noticed within a day or two, the sprayer is probably safe to use on broadleaf crops.

In most cases, herbicide NOTE: Household ammonia or lye may yoaidues can be removed from damage the inner pressure cylinder sprayers by rinsing them out if it is made of brass; in this case, use activated charcoal as below. thoroughly with-soap and water. 'For tractor sprayers: Use two pounds However, the phenoxy herbicides of washing soda or soda ash (a-50-50 (2,4-D, 24-5-7., MCPA, Tordon, etc.) mix of washing soda and lye) 250 grams per 100 liters in the same way as cannot be removed with normal for backpack sprayers. Activated cleaning procedures:and contami- charcoal, if available, will do a very quick job in just two to three nated sprayers may cause damage minutes when Used at 1 kg per 100 when used to apply pesticides liters. Rinse out the sprayer with soap and water afterwards. to broadleaf crops. In fact, Symptoms of pherioxy herbicide damage: farmers should preferably use a Only broadleaf plants are affected. separate sprayer for applying In minor cases, the leaves show a slight. downward curvature. If injury phenoxy herbicides, but reasonably is severe, leaves and stems become good cleaning can be achieved as very curved and twisted with considerable leaf distort: 1. follows:. All washing should be done at a site For backpack (knapsack away from drinking water sources for sprayers: Fill the sprayer people or livestock or water bodies . -with water and addhousehold that might be .polluted by the ammonia at the rate of about wastewater. 20 cc (ml) per liter of tank capacity. Spray part of the mixture out through the dozzle.,fand then let the sprayer sit for a day. Spray out the rest ei the solution and then rinse with detergent and water. To test the sprayer, refill it with

365 378

O Appendix L. Important Planting Skills for Extension Workers

Most extension workers need Calculation of five basic planting skills: 1. How to calibrate a planter. Final Stand

2. How to calculate the probable final stand, given seed The calculation of the final spacing and row width. stand is accomplished 'by the follow- 3. How to calculate the in- row seed spacing needed to ing formula: provide a given population Plant population/ha = at various row widths. 2 100,000,000 cm/ha 4. How Co determine the amount seed spacing of seed needed for a given row width in the row x field s:ze. in cm in cm 5: How to Jetermine a farmer's actual plant population in For example, if the row width is 40 the field using a measuring cm and seeds are Spaced 10 cm apart. tape. the final stand, assuming 100 percent germination and no plant mortality, would have: 100,000,000 50,000 plants 40x10

367 3 79

O Likewise if the crop is planted in Note again that the calcula- hills the calculation made is tion does not account for losses Plant populvion/ba = due to poor germination or plant 100,000,000(cm2 /ha)x mortality. You may want to'plant number of seeds/hill row width (cm) x hill spacing (cm) 15 or 20 percent more than the Thus planting in 50 cm width with amount you wish to harvestinorder .50 cm between hills and two seeds to account for these probable planted per hill yields: losses.

100,000,000 x 2

0-" 50 x 50 80,000 plants/ha

The formula can bt usdd to How to Determine calculate the in-row seed spacing Amount of Seed needed to provide a, given popula- Needed to Plant tion at various row widths. For example. if an optimal population A Given of 100,000 plants/ha is desired, Field Size then: 100; 000,000- 100,000 plants/ha -Row seed You first deed to know how width spacing (cm) many seeds of each crop are con- or: tained in a kilogram. The most ac- 2 row widthlx seed spacing = 1000 cm curate way of calculating this is This gating can be achieved using: to weigh ou.-. a 60 g sample of this 10 cm seed-spacing in 100 seed and count it if you can find a cm row width, reliable scale (i.e. at the post 20 cm seed-spacing in 50 office or at a pharmacy).Multiply-. cm row width, ing the number by 10 will give the 15 cm seed - spacing In annrox. 70 cm- rows, ,etc. number of seeds per kilogram. Other-

368 38 'wise, you can use the table below as to fertilizer. This can be easily a rough guide: .done by counting the plants in Table 15 5-10 randomly, selected strips of Number of Seeds per tilogram row'each equal to.1/1000th of a / hec,iare. Maize 1760-2860 Sorghum 26,400-44,000 Stip 1: First determine the field's Peanuts 100-1540 average row width by meas..: Beans 3000-3960. uring the distance across, Cowpeas .:3960-4040 10 complete rows and ,then 'dividing by 10. Do this To find the kilograms of seed needed at several random lolca- tions to get a represen- number per hectare, simply divide the tative average.

of seeds needed by the number of Step'2: Refer to the 1/1000th seeds/kg. Multiplying this times hectare row len %th chart. 46iihFProPet the size of the field in hectares randomselection procedure. will give the total amount of seed Step 3: Select at random five to ten required. row strips of the appropriate length and count:the number of plants in each and record it. How to Determine Step 4: Hilltiply the Average num- A Farmer's Actual ber of plants in the row Plant Population strips by 1000 to yield. . the plant popm1ationper hectare6

When troubleshooting a farm- .. er s field, it is visually valuable .p to check out his plant population, since this has an important influence on yield potential and response

369

0 381 0 . estimate may be very inaccurate. A random sampling patterni How to Make should be determined before you enter-the field so you will A Pie-Harvest not be tempted to chose them Yield Estimate by visf appearance. 2. Don't co lect yield samples more than one -week before the actual' harvest.

A Ore- harvest yield estimate 4;3. When taking each sample, the area or row length) to be har-. can be aqurate-to within 5 percent, vested must be precisely meas-

of the.a4ual harvested yield if . . ured. Do not estimate: . Remember that any error in the the correct procedure is used._ When sample area size will be mdg-: working with trial and demonstration nified hundreds of times 'when converrirtig the yield to a' plots,.yOu should always take such largerland'unit-basis.. a pre-h4rvest yield sample of- both .4. You. must adjust the sample the test', plot' d the control plot. weightS to aceount for factor like excess moisture, damage? There is always the chance that the and foreign matter. plots might be inadvertently harvested *ore the agreed-upon time

I withoutlhe yields being measured. flowh)Thke ,'re -hare 'ut yield. sampling is also Samples and Estimate Yields I a quick ray of estimating crop i yi..Js in farmers' fields. 1. The Sampling Procedure! L - a. Number of samplese For plolri General Pinciples 'mumthan 0.5 ha, take a mini-. Of Yield Sampling 'mum of five samples. For iplots of over 0.5 ha, take/

' 'between five ant ten. If! , h1. crop growth inot very um.- 1. &Imp es should to collecled at 'form, take to samples. 1 rand m for various portions of / the ield or plot. Do not pur- h. Size of each'sample:Iii Tdke pose .y select samples from each sample/from the sails- 1 high r- or lower-producing sized area or same amount area within the plot(sr your of row length. Individual / .... / ! 1 370 ? sample size should be be- system for row crops is to tween 2.5 and 5.0 square number the rows and select meters. For row crops, the them'at random, thin select area of a sample is deter- the distance into the row mined 171 multiplying row (field). at random. NOTE: length by row wldth. (Har- Exclude tht4e meters or vesting three m4tera of corn-- four rows off perimeter row planted in ttows one from your sampling area meter wide will tgive you a along all four sides of the sampling area of three square plot to enure sampling meters.) Alternatively, Orem the heart of the plot. use a section of row length equal to 1/1000th of a hec- 2. Accuracy: Use a tape to meas- tare. This will make later ure each sampling area or row math calculations simpler, length. -Use an accurate scale and the 1/1000 ha row length to record the total weight of can be taken fret the follow- the samples within one plot. ing table. 3. Hand ing the Samples: The sample should be harvested and 1/1000th hectare pro essed according to local Row Width Row Length prtailing methods. If drying is required before shelling er 50 cm . 10.00 m *_h eshing, be sure the loca-: 60 cm . 16.67 m C..on is secure and free from 70 cm 14.28 m rodents or birds. 75 cm 13:33 m' 80 cm 12.50'm 4. Weighing the Sample: Use an 90 cm 11.11 m accurate portable scale. You 100 cm 10.00 m do not need to weigh'individual llb cm 9.10 m samples separately, but only,' 1 the total ollective sample c: Taking a random sample: from the pldt. If yoilcannot, Decide on the sampling paL- find a good portable scale,---- tein before entering the hive the grain wei0ed in town. field, and do not deviate 5. Checking Grade: Take a random from it. To randomize, the sample of the collective sample / .field can be divided up and have it checked for mois- into seerionsand each sec- ture content and any other tion givten a number drawn gradei qualities if necessary. from a hat. Or you can (Refer to the storage section pick randomized_starting in Chapter 7 for hoW to deter- points at the.side.of the -,ine grain moisture cpptent.) field Mad then enter ran- 'dom istences from the star ing point. A good) 4

371 383 22% moisture! = 78% dry matter, 6. Yield Calculations: 13% moisture = 87% dry matter Size of total' samplearea - 78% x 3500kg/ha = site of 87% No. of individualndividual 3138 kg/ha yield samples sample areas based on 132 moisture .Estimated yield = total size weight of of the plot A Yield collective total sample Estimate sample area Example Yields 7 Crr.ertitill.for Moisture: are usuallybased on grain that Suppose you are taking a is dry enough t?store in shelled form (usually13-14 yield estimate on a farmer's maize percent moisturecontent). If von base,yourestimates on the plot which is slightlyless than weight of a highmoisture sam- 0.5 hectare. The rows are planted ple, you shouldrevise the yield downward using thissimple 90cm apart, and you decide totake dry; the furmnla (otherwise, of grain first). six samples, each consisting 1/1000th hectare of rowlength. (rain weight afterdrying = The collective weightof the Z dry matter before dryin; original shelled, dried maize is18 kg. What X, dry matter grain weight is the estimatedyield on a per after drying hectare basis? lixample: Suppose you weigh a collective sample Solution: of "wet" grain'end then estimate the area of 6/1000ths plot yield to be collected sample of a hectare equal to 3500 kg/ha. 60 sq. meters A moisture testshows 22 per- the sample has 10000 sq.m (1 hectare) what i$ cent moisture; 18 kg x 60 sq. meters the actualyield based mois- on 13 percent 3000 kr /ha ttre? estimated yield

372

384 Glossary

CI-pp...rotation: The repetitive grow- time on the same field: also ing of an orderly succession referred to as intercroppinl. of crops on the same field. Nematodes: Tiny, colorless, thread- Field trial: An on-farm trial re- like roundworms that live in peated simultaneously on a the soil and parrsitize plant

' number of local farms to com- roots. pare a new practice or "pack- Nitro en fixation: The beneficial pro- age" of practices with the pre- cess by which Rhizobia bacteria sent practice or practices. It convert atmospheric nitrogen in- is designed to obtain informa- to a usable form for plants. tion, not as a demonstration. Rhizobia bacteria are associated rungicide: Any pesticide that kills only with legumes. or halts the development of Phosphorus fixation: The process by fungi.' which added fertilizer phos- Herbicide: Any pesticide that kills phorus becomes tied-up as in- weeds. soluble compounds in the soil Hybrid: A type of improved crop var- and unavailable to plants. Phos- iety produced by crossing two phorus fixation is a problem on or more inbred lines of a crop. all soils but is especially sev- Legume: Any plant belonging to the Leg- ere on highly weathered, acid, uminosae Family whose members all red tropical soils. produce their seeds in pods. Leg-Pulse: A legume crop whose mature dry umes can satisfy part or all of seeds are suitable for human con- their nitrogen needs through a sym- sumption; examples are beans, biotic relationship with Rhizobia cowpeas, soybeans, chickpeas, and bacteria that form nodules on the mungbeans. roots. Beans, cowpeas soybeans, Result test: See field trial. mungbeans, lima beans, chickpeas, Rhizobia: A type of bacteria associated pigeonpeas, and peas are legumes. with legumes and capable of nit- Monoculture: The repetitive growing of4a rogen fixation. single crop on the same field yearSoil texture: The relative amount of after year. sand, silt, and clay in a given ultiple cropping: The growing of two or soil. more different crops at the same Soil tilth: The current physical con-

373 385 dition of a soil in terms of its workability and ease of moisture absorption. A soil's tilth can vary markedly with its texture, humus content, and current moisture content. Systemic insecticide: An insecticide that is absorbee into the plant sap and trans'ocated (transport- ed) throughout the plant. Threshing: The process of separating the seeds of cereal and pulse crops from the seedheads, cobs or pods. Tillering: The production of side- shoots by a crop during its growth; tillering is common in mil- '1 let and sorghum. Transpiration: The loss of soil moisture by plant root absorption and passage into the air through the leaf pores. Winnowing: The process of separating chaff and other light trash from threshed grain using wind, fan- driven air or screens.

374

386 t-,

.40

ti Bibliography

Disease identification And Control

American Phytopathological Society. insects, and hunger signs along "A Compendium of Corn Dis- with control measures. Avail- eases." American Phytopatho- able in English and Spanish. logical Society, 3340 Pilot International Crops Research Institute Knob Rd., St. Paul, Minnesota (ICRISAT). "Sorghum and Pearl 55121. Very complete and Millet Diseases Identification also includes control meas- Handbook." Information Bulletin ures. No. 2, ICRISAT, P.O. Patancheru Clemson University Cooperative Exten- 502 324, Andhra Pradesh, India. sion Service. "Soybean Dis- One free copy. Available in eases Atlas." Clemson Univer- English, French, and Spanish. sity Cooperative Extension Handy pocket guide but gives Service, Clemson, South Caro- little information on control lina 29631. One copy free. methods. Includes identification and International Maize and Wheat control. Improvement Center in Mexico

. "Soybean Insects, Nema- (C/MMYT). "Maize Diseases: todes, and Diseases." Circu- A Guide for Field Identifica- lar 504, Clemson University tion." Information Bulletin Cooperative Extension Service, No. 11, CIMMYT, Apartado Pos- Clemson, South Carolina 29631. tal 6-641, Mexico o, D.F. International Center for Tropical One copy free. Available in Agriculture in Colombia English and Spanish. Handy (CIAT). "Field Problems of pocket guide to identifica- Beans in Latin America." tion but gives little infor- CIAT, Apartado Aereo 6713, mation on control methods. Cali, Colombia. $5.60 plus Texas Agricultural Extension Service. postage. Includes diseases, "Sorghum Diseases." Bulletin

375

387 1085, Texas Agricultural Exten- age.ACTION/PC Program and sion Service, Texas A&M Univer- Training Journal Series No. 2. sity, College Station, Texas Peace Corps/ICE, 806 Connect- 77843. Includes both identi- icut Ave., N.W., Washington, fication and control. D.C. 20525.Very comprehen- United States Department of Agricul- sive and includes design ture. "Bean Diseases: How to details for dryers and storage Control Them." Agriculture Hand- facilities. book No. 225, United States Midwest Plan Service.Low Temperature Department of Agriculture Agri- and Solar Grain Drying_ Handbook. cultural Research Service. Midwest Plan Service, Iowa State Available from the Superin- University, Ames, Iowa 5011. tendent of Documents, U.S.. $3 plus overseas postage. Government Printing Office, Ohio State University. "Corn Harvest- Washington, D.C. Not as com- ing, Handling, Marketing in Ohio.". plete as the CIAT bulletin. Bulletin 502, Cooperative Exten- sion Service, Ohio State Univer- Grain Storage sity, Columbus, Ohio 43210. And Drying Purdue University Cooperative Extension Service. "Selecting a Grain Drying Method." Bulletin AE-67, Baikaloff, A. "A Crop Drying Guide Purdue University Cooperative for the Queensland Peanut Extension Service, Lafayette, Grower." Peanut Marketing Indiana 47907. Board, Kingaroy, Queensland, Australia. $2 U.S. plus post- Hunger Signs age. Covers low-temperature, forced-air drying of bulk and In Crops bagged peanuts using motor- - driven fans. Food and Agriculture Organization of Aldrich and Leng.Modern Corn Produc- the United Nations. Handling tion, 2nd ed. F&W Publishing Co., and Storage of Food Grains in 22 E. 12th St., Cincinnati, Ohio. TroEical and Subtropical Areas. CIAT. Field Problems of Beans in Latin Food and Agriculture Organi- America. 1978. Series GE-19, zation of the United Nations, CIAT, Apartado Aereo 6712, Call, Via delle Terme de Caracalla, Colombia. 00100; Rome. Sprague, H.W., ed. 4.964. Hunger Signs Lindblad, Carl. Programming and in Crops, 4th ed. David McKay Training for Small Farm Grain Co., New York. Avail- able from Peace CorpstICE, 806 Connecticut Ave., N.W., Wash- ington, D.C. 20525. Lindblad, Carl, and Laurel Druben. 1976. Small Farm Grain Stor-

376 388 Implements and P.O. Box 5125, Raleigh, NC 27650. Equipment Single copy price for 1981 is $5.00 plus postage. Comprehen- sive guide to pesticide selection, Watson,.Peter. 1981. Animal Trac- safety and dosages. tion. Peace Corps/ICE. Covers the selection and car- Soil Management ing of draft animals and the And Fertilizer Use use of basic animal-drawn tillage and cultivation equipment.

Peace Corps. 1981. Soils, Crops, and Insect Fertilizer Use. Peace Corps/ICE, Identification Reprint R8. A what, how and why And Control guide to soil management, determining fertilizer needs, and using organic and chemical fer- CIAT. Field Problems of Beans in tilizers appropriately under 'Latin America. CIAT. Apar- small farmer conditioni. tado Aereo 6713, Cali, Colom- bia. $6.50 plus postage. Fichter, G. insect Pests. Western Publishing Co., 1220 Mound Weed Identification Ave., Racine, Wisconsin And Control 53404. $2.95 plus postage. Excellent pictorial and des- criptivepocket guide of Clemson University. "Weeds of the worldwide usefulness. Southern U.S."Clemson Univer- Hill, D. Agricultural Pests of the sity Cooperative Extension Ser- Tropics. Cambridge Univer- vice, Clemson, SC 29631.Con- sity4Press, London, 1975. tains pictures and descriptions A useful addition for a Peace of some 150 common weeds of the Corps in-country ag library; tropics and sub-tropics. well illustrAed.

Winged Beans Pesticide Use

National Academy of Sciences. "The Division of Continuing Education. Winged Bean: a High Protein Crop "North Carolina Agricul- for the Tropics."Available tural Chemicals Manual" from that National Technical (revised yearly). Division Information SerIlice, Springfield, of Continuing Education, 'VA 22161. 45 pages. $450. Single copies free. 377 ag

United States Department of AgricUl- ture. 1978. "Vegetables of the Rot-humid Tropics: -Part I: The Winged Bean." United States Department of Agricul- ture Agricultural Research Service. Available from the Mayaguez Institute of Tropical Agriculture, Box 70, Mayaguez, Puerto Rico 00708. 22 pages. Questions some of the claims made for the crop. University of Illinois. The Winged Bean Flyer. University of Illinois Department of Agron- omy, Urbana, Illinois.A newsletter devoted to the winged bean.

378 390 .. t References

For more specific information TheInternational Potato- Center, Peru on crops contact the follow- (CIP). Address: Apdo. 5969, ing international crop inpro- Lima, PERU, S.A. vement associations: TheInternational Rice Research In- The International Center for Tropical stitute, the Philippines (IRRI). Agriculture in Colombia (CIAT): Address: P.O. Box 583, Manila, focuses on maize, beans, and PHILIPPINES. casava (manioc). Address: A- partado Aereo 6713, Cali, Col-

. ombia. The. International Crops Research In- stitute for the Semi-arid Tropics in India (ICRISAT): focuses' on millet, sorghum, peanuts, chickpeas, and pigeonpeas. Address: Patancheru P.O., Andhra Pradesh 502 324, INDIA The International Institute for Tro- pical Agriculture, Nigeria focuses on maize, grain legumes (cov peas, lima beans, soybeans), rice, root and tuber crops. Address: Oyo Road, PMB 5320, Ibadan, NIGERIA, lest Africa. Also has a farmin systems research program. The International Maize and Wheat Im- provementCenter in Mexico (CIMMVT). .Address: Londres 40, Apdo. Postal 6-641, MEXIC046, D.F.

379

391 A

Sources of Illustrations

Page Illustration and Source 22 it Illustration add,Source 14 Rainfall graph - -John Guy Smith, 65 Peanut plant -- Original drawing by 1970, "The Agricultural_Envi- M. Kaufman. ronment", Peace Corps/Latin 70 Bean plant and pod--La Caraota, America Agriculture Program extension pamphlet, Conseho de Guide Manual Part 3, Unit 1. Bienestar Rural, Venezuela, 14 Cropping chart--Ibid. 1965. 31 Cropping calendar, distribu- 109-112 Implements- -John Boyd, Tools tion of work--Ibid. for Agriculture: A Buyer's 32 Demand for production credit- - Guide to Low-Cost. Agricultural Ibid. Implements, Intermediate Tech- 36 Germinating maize seed-- Origi- nology Publications% Ltd., nal drawing by M. Kaufman. London. 37 Germinating bean seed - -Web- 113 Raised beds, land leveling--Same ster's Illustrated Diction- as for page- 37. 125 Animal-drawn planter, hand-puihed fertilizer applicator- -Same as 38 Nitrogen-fixing nodulesOri- ginal drawing by M. Kaufman. for pp. 116-119. 125 41 Maize tassel, ear of maize- - IITA plantersMA information Original drawing by M. Kauf- bulletin. 179 WeedsGeorge Ware, 1980, Com- man. plete Guide to Pest Control, 42 Parts of young maize plants- - University of Arizona, Thom- Original drawing by M. Kauf- son Publications, Fresno, CA., man. 185 Animal-drawn cultivatorSame as 51 Grain sorghum plant nearing maturityOriginal drawing for pp. 109 -1.2.- by.M. Kaufman. 186_ Tractor -drawn cultivator- -Same as for page 37. 5I Grain sorghum seedhead--Ori- Cultivator shovels, sweepsOri- ginal drawing by M. Kaufman. 187 ginal drawing by M. Kaufman. 59 MilletsHow a Sorghum Plant Boom backpack sprayerRice Pro- Develops, pamphlet, Kansas 197 duction Mandal, University of State University Co -op the Philippines and IIRI. Extension Service.

381 0 392 4

. Page Illustration and Source 200 Insects--United States Depart- ment of Agriculture. 201 Insects--George Ware, Univer- sity of Arizona, 203 Aphids--United States Depart-

, ment of Agriculture. 205 Midge--United States Depart- ment of Agriculture. 207 Sorghum shoot fly and damaged plant--D. Hill, 1975, Agri- cultural Pests of the Tropics and Their Control, Cambridge University Press, London. 207 Thrips--Brochure, Florida Agricultural Experiment Station. 208Mite, leafhopperSame as page 192. 209Mexican bean beetle--Ibid. 225 Spray patterns--Original drawing by K. Kaufman. 226Tractor boom spray nozzle arrangement--Rohm & Haas Co., Philadelphia, Pennsylvania 255. Mixing drum--Same as for page 37. 262Nematodes--Same as for page 37. 274 Hand maize sheller--Bulletin on the hand maize sheller, Tropical Products Institute, Buckinghamshire, United King- dom.

382

1 ,393 Index O

Agricultural development 2 Daylength 11 a" Agricultural environthent 9 Diseases Aluminum toxicity 169 beans 249-54 fungal, bacterial, viral 229-31 Beans {Phi aseolus vulgaris) maize 235-41 adaptation69-70 methods.of control 231-4. distribution 69 millet 244-5 diseases 249-5A peanuts 245-9 fertilizer recommendations167-8 sorghum. 241-4 improvement programs87-9 Drying insects 208-10 f, determining grain moisture 285-6 nutritional value 38-40,91 methods 286 plant population 132 safe moisture content 281-4 types 69-70 weed control 188 Ecology 17-18 Birds 65-7 Extension worker orientation of 25-32 Calcium 141 role of 7 Cereal crops 35 Compost 149 Fertilizer burn160-1 Cowpeas 71-3 Fertilizers Crop residues 106 application methods. 152-7 Crop rotation 91-4 effect of soil pi 170 Crop improvement programs foliar 159-60 beans 89 organic versus chemical 145-9 cowpeas 90 rates 161-9 maize80-81 Forage sorghum .48 millet 84-5 Fungicides 'peanuts 85-7 application guidelines 257 sorghum 81-4 foliar 258 Cropping calendar 30-1 seed treatment254-5 Cropping systems 28 soil 257 Cultivators 185-8 Cutworm baits 218 Germination test 121-2 Grain sorghum (see sorghum) Green manure crops 94

394 1

Liming 169-72 Green Revolution 295 Groundnuts (see peanuts) Maize 'adapation 40-1 HarroWs, types of 109-10 distribution40 Harvesting diseases235-41 282-3 beans fertilizer recommendations 163-4 cowpeas 282-3 harvesting269-70 losses 269-71 improvement programs80-81 272-9 maize hi-lysine varieties43 millet 274 -6 insects200-204 peanuts 277-8'.! nutritional Value 38-40 sorghum- 274-6 plant population 129-30 Herbicides 182-3, 190-7 types 40-3 15 Humidity weed control 188 Hydrocyanic acid 55 yields43 Hybrids 118 Manure147-9 Millet Innoculation 166 distribution 59-61 Insect control 244-5 212 diseases biological fertilizer recommendations 165 chemical213-5 274-6 212 harvesting cultural improvement programs 84 -5 integrated 215 insects 206-7 organic "213 nutritional value 62 Insecticides photosensitivity 63 chemical classes 219 plant population 131 dosage calculations220-3 tillering63 fol.m.;JktionS 217-9 types 59-61' syt.te.r..- versustion-lystlmic yields. 61 216-7 Monoculture 91-3 InJects Mulching 174;181 beans 208-10 91-2, 95-9 cowpeas .21011 Multiple cn:opping identifying 199 Nematodes 0 life cycles 198 diagnosis261-3 maize 200-204 controls 263-5 millet 206 Nematodices264-5 peanut 207-8 Nitrogen sorghum204-6 available versus unavailable storage 204, 290-94 139 92, 95-8 Intercropping application methods 152-4 Irrigation *174-5 leaching losses of 139-40 Nitrogen fixaton 37 Land preparation 101-16 Legume 35-7

384 n. 395 Organic fertilizers147-50 Seed selection 119-21 Seedbeds 113-14 Package of practices approach 6 Shifting cultivation 99-101 Peanuts Slash and burn agriculture 99-101 adaptation 66 Soil texture 16 distribution 63 Soil tilth 17 diseases 245-9 Soil testing 143-4 fertilizer recommendations165-7 Soil pH 17, 169-72 harvesting 277-82 Sorghum improvements programs85-7 adaptation53-4 insects 207-8 diseases239-42 nutritional value 66-7 fertilizer recommendations 164-5 plant population 131-2 harvesting271-72 land preparation 115 hydrocyanic acid in 55 types 64 improvement programs 81-4 weed control 188-9 insects 205-6 yields 64 nutritional value56-7 Phosphorus photosensitivity 54-5 application guidelines 140, plant population 125-31 154-6 ratooning55-6 fixation 138-9 tillering 55-6 pH (see soil pH) types50-53 Photosensitivity 10 'yields 53 Plant population 129-33 Spike-tooth harrow111-12, 184 calculating the final stand 365 Sprayers194-7 recommendations 129-32 guidelines for using 196, 223-8 Planters nozzle types 224-7 types of 123-6 Storage Planting insects 204, 290-94 depth of. 134-5 methods ,284-6, 295-7, 288-90 equipment 123-6 Striga 189-90 hill versus drill 128 Systemic fungicides 258 -9 methods 123-6, Systemic insecticides 216-17 Potassium 140, 157 Pulse crops 35-38 Temperature 11-12 Plant spacing 126-9 Threshing 271 Tillage Quelea bird 266 depth of 105-7 equipment 107-13 Rainfall 12-15, 30' methods 101-7 Rhizobia bacteria 37 Rodents 267 Virus diseases 230-31 Rototiller 110 Row width 128-9 Water management 172-5 Weed control 180-90

385 396 pre-planting180-83 post-planting183-90 Weeds annual versus perennial 178-80 broadleaf versus grassy versus sedge 178 identifying 180

Winnowing 272

Yield guidelines cowpeas 72 maize 43-4 millet 61 peanuts 64 sorghum50-53

peeSIFS-se 0 386

397 Since 1961 when the Peace Corps was created, more than 80,000 U.S. citizens have served as Vblunteers in developing countries, living and working among the people of the Third world as colleagues and co-workers.Today 6000 PCVs are involved in programs designed to help strengthen local capacity to address such fundamental concerns as food production, water supply, energy development, nutrition and health education and reforestation.

Loret Miller Ruppe, Director Edward Curran, Deputy Director Designate Richard B. Abell, Director, Office of Program Development

Peace Corps overseas offices: SIERRA LEONE BELIZE FIJI MAURITANIA Private Mail Bag P.O. Box 487 BP 222 P.O. Box 1094 Freetcwn Belize City Suva Nouakchott SOLOMON ISLANDS BENIN GABON . MICRONESIA P.O. box 547 BP 971 BP 2098' P.O. Box 336 Honiara Cotonou Libreville Saipan, Mariana Islands SWAZILAND WJraINAJAA GAMBIA, The P.O. E7362 P.O., Box 93 P.O. Box 582 MOROCCO Mbabane Gaborone Ban3ul 1, Zanquat Benzerte Rabat CAMEROUN GHANA TANZANIA bF P.O. Box 5796 NW-frYI Yaounne Accra (North) NEPAL Dar as Salaam P.O. Box f13 Kathmandu CENTRAL AFRICAN GUATEMALA THAILAND REPUBLIC 6a Avenida 1-46 42 Soi Sonprasong 2 BY 1080 NIGER Zona 2 Petchhuri Road BP 10537 Bangui Guatemala Bangkok 4 Niarey HONDURAS CuSTA RICA* 40G0 Apartado Postal BP 3194 kartano Postal OMAN C-51 Lore 1266 Tegucigalpa P.O. Box 966 San Jose muscat JAMAICA TONGA PAPUA NEW GUINEA 9 Musgrove Avenue BP 147 P.:). Box 1190 Kingston 10 Nuku'Alofa Boroko KENYA oolt,IcAN RLPUI.LIC TUNISIA P.O. Box 30518 B.P. 96 Apartano Postal PARAGUAY Nairobi 1002 Tunis - Belvedere 1414 c/o American Embassy Tunis Santo Domingo LEsortio Asuncion P.O. Box 554 UPPER VOLTA EASTERN CARRIBBEAN Maseru Incluaing: Antigua PHILIPPINES 14757:3Wildin Ouagadougou Barnaros, Grenada, LIBERIA B.O. Box 7013 Montserrat, Box 707 Manila St. Kitts-Nevis, Monrovia WESTERN SAMOA St.Lucia,St. RWANDA P.O. box PRO Vincent, bominica c/o American Embassy MALAWI Apia "Erin Court" box 208 Kigali bishops Court Hill Lilongwe YEMEN P.O. box 696-C SENEGAL Bridgetown, Barbados P.O. Pox 1151 MALAYSIA X34 Sana'a 177 Jalan Raja Muda Dakar Kuala Lumpur- ECUADOR ZAIRE SEYCHELLES BP 697 Casilla 635-A MALI Box 564 Kinshasa Quito BP 85 Victoria Bamako

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