Annual Meeting Georgetown, Guyana 1911

CARIBBEAN FOOD CORPS SOCIETY

PUBLISHED WITH THE COOPERATION

OF THE

UNIVERSITY OF PUERTO RICO

MAYAGUEZ CAMPUS

1980

VOLUME IX

TABLE OF CONTENTS

Page

Observations on the Intercropping of Maize and Pigeon Peas (Cajanus indicua Spreng) on a "Red Earth" in Grenada, W.I. 1

Trial of Phytohormones to Improve Tomato Fruitset in Guadeloupe 11

Some Problems Involved in the Production of Vegetables in the Commonwealth Caribbean 15

Observations on the Causes of the Poor Coconut Yield in the Pomeroon, Guyana 19

Distribution of Dry Matter and Mineral Nutrients in the Tubers of Two Cultivars of Dioscorea alata L. 23

Some Problems Involved in the Production of Vegetables in the Commonwealth Caribbean 35

Some Information About Peasant Rice Farming in Nickerie (Suriname) 36

Vegetable Cultivar Screening Trials 1970 - A Progress Report 42

Fungicide Field Trial Against Eggfruit Anthracnosis 52

Influence of Air Temperature and Humidity During the Vegetative Growth on Some Structural Characteristics of the Leaf of Capsicum annuum L. 56

A Comparative Trial of Cucumber Varieties and Hybrids in Guadeloupe 64

The Choice of a Citrus Rootstock, Resistant to Tristeza for Guyana 71

Soil Resources of Guyana 79

Response to Phosphorus and Potassium Fertilizers on Soybeans (Glycine max L. Merr.) Along Coastal Lands 97 Page

Sew Information About Dioscorea trifida (Cush-Cush Yam) Selection 104

A New Look at Pigeon Peas 111

Studies on Coconut Caterpillar, Brassolis sophoras Linnaeus and moth borer, Castnia daetiajus Cramer, Two Major Pests of Coconut Pa Ire, in Guyana 122

Contribution of Agriculture to Guyana's Economy 138

Performance of Soybeans (Glycine max (L.) Merrill CV 'Jupiter') in Guyana as Affected by Inoculum (Rhizobiun japonicum) and Nitrogen 14 9 The Pattern of Crop Production in Guyana 15 9 Some Recent Studies on Rice Pests in Guyana 16 7 OBSERVATIONS ON THE INTERCROPPING OF MAIZE AND PIGEON PEAS (CAJANUS INDICUS. SPRENG) ON A "RED EARTH" IN GRENADA, W.I.

Ronald A. BaynesI/

INTRODUCTION Intercropping in the tropics is very much an accepted form of agriculture, particularly among small farmers in the production of annual food and cash crops. In St. Vincent a popular mixed stand is maize and peanuts, while in Barbados the intercropping of sugarcane with sweet potatoes or yams is common place. Large farmers in St. Lucia and to some extent in St. Vincent successfully intercrop coconuts with bananas.

Subsistence farmers in Nigeria were reported to be reluctant to abandon multiple cropping of millet and cow peas for pure stand cultures. Norman (1970) reported that information collected in a study of the effects of intercropping in Northern Nigeria was inconclusive. That is to say, that there was no clear-cut demonstration that sole cropping was superior to multiple cropping.

Experience in Mauritius with intercropping was favourable. Extremely good results were obtained when sugar cane was intercropped with Solanum potatoes (Rouillard 1967). Here the potato yields were significantly enhanced and the sugar production per unit area was unimpaired. The observations were so encouraging that large scale plantings were recommended, in which two rows of potatoes were seeded on every sugar cane inter-row. Ying and Sheung (1964) reported from Taiwan that peanuts interplanned in sugar cane resulted in improved yields of both crops, that soya bean did not affect the yield of sugar cane, however that sweet potato and tomato decreased sugar cane yields by about 12%, while flax and cotton were seen to depress cane yields by 20 and 15%, respectively. They further reported that yield depressions notwithstanding, net revenue from multiple cropping was higher than from sole cropping.

Critical observations in the Caribbean have been few. Williams (personal communication) noted that the intercropping of bananas with tannias in St. Vincent resulted in very serious yield depressions of both crops which apparently were not compensated for by the joint revenue.

In Grenada, the traditional method of producing pigeon peas, is to seed it at the same time as maize in the same planting hole at the onset of the wet season. No systematic study was hitherto done to examine the efficacy of this system of production.

' This paper reports on a field experiment in which the traditional maize pigeon pea mixed stand was compared with pure stands of both crops and a method in which maize and pigeon peas were put in alternating holes within the row.

1/ Agronomist, University of the West Indies, Cave Hill, Barbados, W.I. - 2 -

MATERIALS AND METHODS

The experiment was sited at Mirabeau Agriculture Station in Grenada, Windward Islands, on a Capitol Clay loam at an elevation of about 200 metres above sea level. This soil is an excessively drained "Red Earth" developed over deeply weathered basic igneous material, in an area which normally experiences an annual rainfall of 2000 to 2500 mm. The soil is deep, well structured physically and acid in reaction with a pH of 5.4 - 5.6 (Vernon et al 1959).

The experiment consisted of four randomized complete blocks of four treatments each. The treatments were as follows:

(1) Pure stand maize - in which maize was planted in 91.4 cm rows, 30.5 cm in the row, to give a plant density of about 35.9 thousand plants per hectare.

(2) Pure stand pigeon peas. Here peas were planted in 91.4 cm rows, 61 cm between plants in the row, to give a plant density of 17.9 thousand plants per hectare.

(3) Traditional method. Corn and peas were seeded in the same planting site, three seeds per hole. Rows were 91.4 cm apart and planting distances within the row were 91.4 cm. No thinning was done, so that assuming all maize seeds developed, the population would be the same as if it were planted in pure stand. On the other hand if all pigeon pea seeds developed the plant population would be double that of the pure stand peas.

(4) Alternating holes method. In this method, maize and pigeon peas were seeded in alternating sites 30.5 cm in the row, the rows being 91.4 cm apart. Both corn and peas were thinned back at the 3-5 leaf stage to one plant per planting site such that the total population would be 35.9 thousand plants per hectare.

The net plot size from which harvesting was done was 1/747.175 hec- tares in respect of treatments 1,2,3 and the peas in treatment 4. In treatment 4 - the maize was harvested from an area of 1/666.9 ha.

A non-determinate local selection of pigeon peas was used, while tropical hybrid X304 was the maize employed.

Planting was done on the flat after hand cultivation. Chemical fertilizers were applied at seeding time at the following rates to all plots:

Sulphate of Ammonia 440 kg. per hectare Triple Superphosphate 190 kg. " Muriate of Potash 125 kg. "

Weed control was effectively done by hand weeding and regular sprayings of Malathion or Rogor controlled insect pests. - 3 -

Weekly plant heights were measured for both crops from five plants in each plot selected at random. Corn was harvested after 16 weeks and grain moisture and shelling % were determined from a 12 ear random sample. Pigeon peas were harvested dry, four pickings being done over a two month period.

In determining the gross revenue the prices per unit weight in operation in Grenada during January 1971 were used. These were twenty two and fifty five Eastern Caribbean cent3 per kilo for dry maize and pigeon peas respectively.

RESULTS

Rainfall recorded at Mirabeau for the duration of the experiment shows that the pigeon peas received a total of 1724 mm of precipitation over a 35 week period, while the 17 week maize crop received 989 mm. (Fig. 1). Rainfall distribution appeared to be adequate for both crops for most of the growing season, except for the last five weeks of the pigeon pea crop, during which time the mean weekly rainfall was less than 25 mm.

The plant growth rate of maize was much faster than that of peas (Fig. II). White maize attained a mean plant height of about 230 cm in eight weeks, the peas were observed to be 80 cm at that time.

Maize plant heights did not appear to be influenced by intercropping with pigeon peas, as pure stand corn did not elongate faster than in the traditional mixed stand or corn in the alternating holes method. Through- out the growing season, the plant heights were about the same and at eight weeks after seeding when tasseling was complete, maize in the traditional mixed stand had a mean height of 231.5 cm as compared with 226.4 cm in the pure stand and 218.3 cm in the alternating holes method.

Pigeon pea plants were materially affected by intercropping systems. Between the second and eight week after seeding, there did not appear to be any serious differences in plant growth. However, by the eleventh week after seeding, pure stand peas had outstripped both mixed stands. On the sixteenth week after seeding, when the last plant height measure- ments were taken, pure stand peas were taller than all other entries, with a mean height of 258.3 cm. This was significantly taller than the 187.6 cm in respect of the peas in the traditional mixed stand.

Mean grain yield recorded from the maize pure stand culture amounted to 3.69 metric tons per hectare (15.5% moisture) as compared with 3.19 metric tons per hectare (15.5% moisture) from the traditional mixed stand (Table 1). The difference between these mean yields was not significant. Mean grain yield of maize from the alternating holes method, however, was significantly lower than the pure stand method, this being 2.43 metric tons per hectare (15.5% moisture). - 4 - - 5 -

Fig. XI. Maize and Pigeon Peas Plant heights (era) commencing 2 weeks after seeding.

Weeks after seeding 22/V11/70 28A/70 6

labia 1. Maize Grain Yield (Metric tons per ha., 15.556 moisture)Grain moisture at harvest, shelling % and mean ear weights (gms), in mixed and pure st stands.

Grain Grain Shelling Mean Stand Yields Moisture % % Ear weight Traditional 3.19ab 31.9 75 207 Pure stand 3.69a 28.5 73 206 Alternating 2.43b 72 222 S.E. +0.18 N.S.D. N.S.D. N.S.D.

Table 2. Yields of sun dry pigeon peas (Metric tons per hectare) in mixed and pure stands.

Stand Tons per hectare

Pure stand 2.34a Alternating 1.94b Traditional 1.42c S.E. +0.11

Table 3. Estimated Revenue, Expenditure and net income (Eastern Caribbean Dollars) from Maize and Pigeon pea cultures.

Stand Gross Revenue Expenditure Net Income Alternating E.C.$1601 E.C.$756 845 Traditional 1482 857 625 Pure stand Peas 1287 852 435 Pure stand Maize 812 543 270 - 7 -

Maize grain moisture content at harvest varied from 28.5% in the pure stand to 31.9% in the traditional method. Differences were, however, not significant (Table 1). It could be concluded from this, that the maturity characteristics of X304 were not impaired by cultural methods. Similarly, neither maize shelling % nor mean ear weights appeared to be influenced by methods of production. Shelling % varied from 72 in respect of the alternating holes method, to 75% for the traditional method; and mean ear weights varied from 206 gms in the pure stand method to 222 gms in the alternating holes method (Table 1).

Sun dry pigeon peas yield from the pure stand was 2.34 metric tons per hectare which was significantly larger than the pea yields from the alternating holes method which amounted to 1.94 metric tons per hectare. The lowest mean yield recorded was 1.42 metric tons per hectare from the traditional method which was significantly inferior to the other methods (Table 2). Pure stand pigeon peas had a tendency to be associated with an earlier crop than was the case with other methods. While about 1/3 of the total crop was harvested at the first picking from the pure stand, only 16% of the crop was harvested from the traditional method and only 18% of the total out-turn from the method of alternating holes (Fig. III).

In money terms, the method of alternating holes provided the largest estimated gross revenue and net income, these being E.C. $1601 and E.C. $845 per hectare, respectively. The traditional method yielded an estimated net revenue from peas and corn of E.C. $625, while pure stand peas provided E.C. $435 and pure stand maize E.C. $270 per hectare (Table 3).

DISCUSSIONS AND CONCLUSIONS

The results clearly indicate that the question of multiple cropping in the tropics deserves greater in depth study before pronouncements are made on them. It is also clear that different crop species possess different intercropping tolerances, which need to be identified by systematic investigation of different crop genera, plant densities and spatial arrangements. Soil fertility, moisture and nutrient adequacy, as well as effective weed and insect pest control will be important considerations.

It is obvious that both crops, maize and pigeon,peas, suffered as a result of intercropping. This was particularly true of the pigeon peas, which in the traditional mixed stand yielded only 60.7% of the crop produced in pure stand. This was apparently due to serious competi- tion among plants. The peas, growing at a slower rate than maize, were clearly surpressed. Maize,on the other hand, was more aggressive, com- pleting its elongation in eight weeks, despite the presence of the peas.

In the final analysis the most important consideration for the farmer is the net income on his investment. Any system which tends to increase his real income on a continuing basis must of necessity be - 8 - - 9 - preferred. The alternating holes method clearly did this. The system caused no serious yield depressions. In any event the combined yields from maize and pigeon peas more than compensated for the slight yield short falls experienced.

It could be concluded that:-

(1) Intercropping of maize and pigeon peas leads to depressed yields of both crops.

(2) The method of alternating holes resulted in the smallest yield depressions, hence the combined cropping provided the largest net return per unit area per unit of time.

(3) The traditional method should be discouraged in the interest of an expanded pigeon pea industry, since Grenada and the Caribbean are protein short, and pigeon peas provide an important, though seasonal supply of this essential food.

(4) Since farmers are expected to be reluctant to abandon intercropping, the method of alternating holes might with advantage be introduced.

(5) There is a great need to understand the multiple cropping systems indigenous in tropical agriculture with the view towards improving their contribution to production. Further work is required with a range of plant genera, in a range of plant densities and spatial arrangements.

SUMMARY

Two methods of intercropping Pigeon Peas (Ca.j anus indicus. Spreng) and Maize were compared with pure stands of both crops, on a "Red Earth" in Grenada.

The traditional method of seeding both crops at the same time in the same planting site, resulted in a large reduction in dry pea yields when compared with the pure stand. Maize yields were, however, not materially affected, although the short fall in yield amounted to 0.5 metric tons dry (15.5% moisture) grain, per hectare.

In terms of cash income, a system of alternating Maize planting sites with Pigeon Pea sites in the same row appeared to provide the highest net income per unit area.

ACKNOWLEDGEMENTS

Thanks are due to Mr. D. Noel, Senior Agricultural Officer, Ministry of Agriculture, Grenada, who discussed the problem with the author. Acknow- ledgement is also made of the valuable contribution rendered by the Field Staff of the R.F.E.P., Grenada, who managed the experiment on a day to day basis. - 10 -

REFERENCES

Norman, D.W. (1968). Why Practice Intercropping. Samaru Agr. Newsletter in Trop. Abstr. Vol. 25. March 1970.

Rouillard, G. (1967). Mauritius Sugar Industry Research Institute Ann. Rep.

Vernon, K.C., Payne, Hugh and Spector, J. Soil and Land Use Surveys #9, Grenada. I.C.T.A., U.W.I., Trinidad.

Ying, N.G., Sheung, R. (1964). The Taiwan Sugar Industry and its Experi- ment Station in Mauritius Sugar Industry Research Inst. Ann. Rep. - 11 -

Trial of Phytohormones to Improve Tomato Fruitset in Guadeloupe

G. Anais & F. Kaani^

INTRODUCTION

In the French Caribbean, tomato production is rather limited the year around. The main period of production is the dry season (November to May); in the rainy season there is very little production. Because of this fact, the results are high prices, (which fluctuate from about 05 US dollar per kilogram in the dry season, to 1.5 US dollar in the wet season), and imported tomatoes to supply the local market. There- fore, tomato production demands improvement in tropical countries.

In local areas where diseases are controlled, tomato yields are still low due to poor formation of flower clusters, the low level of fruit set, and insufficient development of fruits.

One of our objectives is to improve fruitset by various means. In countries in the temperate zone, phytohormones are used to improve tomato fruitset in adverse conditions. The present trial was to test such a method under our tropical environment.

MATERIALS AND METHODS

This trial was conducted at our main station at Duclos on a ferralitic soil. The tomato variety used was Floradel grafted on to CRA 66 a bacterial wilt resistant line, in order to avoid occurrence of this disease. These plants were set out in the field, on April 2nd after they had been grafted in the greenhouse.

The experiment consisted of blocks with 4 replicates of 5 plants each. The plants were staked and pruned up to 4 clusters of flowers. The phytohormones tested were: Beta Napthoxy Acetic Acid (Blossom-Set) and N-meta-Tolylphthalamic Acid (Tomaset). These two plant hormones are also known as Duraset and BNOA, respectively. The treatments consisted in spraying flower clusters at the recommended rates, three times a week with a hand sprayer beginning when the first flower was fully open. These treatments were as follows:

a) Unsprayed (control b) Blossomset c) Tomaset d) Blossomset and Tomaset

1/ The authors are greatful, and wish to express their thanks for the technical aid rendered by C. Vincent and J. Manyri. - 12 -

After setting of fruit, they were counted to determine percentage of fruitset. The meteorological data for the 60 day experiment period following planting was 429mm of precipitation and a temperature average minimum of 20 deg. C., and an average maximum of 27.5 deg. C.

RESULTS

The data indicates that there are no significant differences in the treatments (see tables 1, 2 & 3).

DISCUSSION

The use of phytohormones was demonstrated to be ineffective on improving fruitset under the conditions of this experiment. Also it was observed that the hormone sprays did not increase the formation of flowers. - 13 -

Table 1 - Fruit setting

Bloc 1 Bloc 2 Bloc 3 Bloc 4 Mean

Control 62.4 51.8 56.3 58.1 57.2

Blossomset 53.1 •",4.7 50.0 56.3 53.5

Tomatoset 56.7 60.3 54.0 57.1 57.0

Blossomset + Tomatoset 66.7 54.7 60.0 58.8 60.0

- Percentage of fruitset for 3 clusters.

Table 2 - Statistical data

Origine Square LD Variance F F5Z

Total 4,909 15

Treatment 2,926 3 975,33 1,78 3,29 NS

Blocs 1,983 3 661,00 1,21 3,29 NS

Error 3,979 9 545,44 - 14 -

Table 3 - Number of flowers per treatment

Bloc 1 Bloc 2 Bloc 3 Bloc 4 Total

Control 93 85 71 86 335

Blossomset 81 75 78 64 298

Tomatoset 67 63 76 77 283

Blossomset + Tomatoset 75 75 80 68 298

F = 0,33 - F5% = 3,29 SOME PROBLEMS INVOLVED IN THE PRODUCTION OF VEGETABLES IN THE COMMONWEALTH CARIBBEAN

W. deCourcey Jeffers—

This paper attempts to identify some of the more serious problems affecting Vegetable Production in the Commonwealth Caribbean.

The Caribbean Free Trade Association (Carifta) came into being during 1968. Provision was made for an Agricultural Marketing Protocol designed to stimulate, encourage and permit a greater volume of trade in agricultural commodities, including vegetables within the Commonwealth Caribbean area.

In some of the Commonwealth Caribbean territories one-crop economies existed e.g. Montserrat, Cotton; St. Kitts, Sugar Cane; Barbados, Sugar Cane St. Vicent, Bananas. In those islands growing sugar cane and cotton in particular, it became obvious that because of marketing and other problems it was very necessary to diversify their agriculture. With just about all of the Commonwealth Caribbean territories concentrating on developing a tourist industry, it was also seen fit to produce much more local products and therefore import less. It is seen therefore that most, if not all, of the Commonwealth Caribbean territories had more or less the same motives for diversifying their agriculture, and later they tended to have identical objectives of import substitution.

One of the problems encountered in the production of vegetables in the Commonwealth Caribbean is the fact that growing seasons tend to be more or less identical. It is not uncommon therefore to find when there is a glut in one territory of a particular crop, the same is very often true in may of the other territories. This inevitably frustates marketing particularly since vegetable crops by and large are highly perishable and storage facilities could hardly be considered as ideal or adequate in many territories. What is snid of gluts is also true of scarcities, and very often produce has to be imported from the U.S.A. and Canada.

Agricultural Research is expensive. It is very often felt that Research work can be carried out at a central place within the area and the results applied throughout. This might be theoretically true but does not work out in practice, and therefore leads to repetition and duplication. Many of the Commonwealth Caribbean territories are not adequately staffed to do the volume and type of Research on Vegetable Crops that is necessary, Some territories therefore have considerable advantage over others from a research standpoint.

Ministry of Agriculture, Science & Technology Bridgetown, Barbados, W. I. - 16 -

In Barbados over the past four years or so where a vigorous research programme on Vegetable Production has got underway, our experience has shown that without Entomologists and Plant Pathologists on the staff our progranmes would not have succeeded. It Is questiona&le, therefore, how far a territory can get without what may be considered as basic staff.

In many of the Commonwealth Caribbean territories the labour force is somewhat Inadequate and to further diversify will inevitably involve far greater use of mechanical equipment. In many of the territories, particularly the smaller ones, most of the terrain is unsuited to mechanisation. In the near future, territories that cannot mechanize are likely therefore to be at a considerable disadvantage.

The climate is generally the same with only slight variations between some territories. Basically they all tend to have a rainy or wet season and a dry season. In some territories the wet season might be slightly Ion ger and wetter, and in others the dry season might be longer and drier. In the most of them, the wet season presents identical problems i.e. the incidence of pests and diseases are higher and difficulties are experience in controlling them. Where a heavy or sticky soil exists, land preparation and cultivation presents a tremendous problem during the wet season. In most of f:h

Planting material for vegetable crops is generally available throughout the area. Private enterprise as well as Governmental Establishments in some territories are importers of planting material. In some territories, however the importation of planting material is left almost exclusively to private enterprise. In such cases, planting material tends to be ordered from Cata- logues rather than as a result of local trials. This practice can present problems since in some cases factors such as day length and photoperiodism are not taken into account upon ordering.

Recently in Barbados our experience has been that Cabbage Seed imported from reputable seed companies are affected by bacterial diseases. It has been necessary to pretreat Cabbage Seeds before planting. This has been practical in Barbados because a qualified staff is available, together with the fact that the necessary equipment is available. Since Government through the Ministry of Agriculture is probably the largest importer of vegetable planting material also ensures that a fair amount of treated planting material is readily available. With the expansion of vegetable crops throughout the Commonwealth Caribbean, problems of this nature are sure to multiply and some territories will hardly be in a position to cope with such problems. - 17 -

The production of vegetables can generally be regarded as not only a costly business but a particularly risky one, mainly as a result of perishability of the marketable product, and the fact that insects, diseases and even weather conditions can so easily affect the outcome.

Financing vegetable enterprises is probably one of the problems common to all the Commonwealth territories. It is true to say that the problem of finance is generally accepted and efforts are being made to overcome this obstacle by both comnercial banks and Governments.

Marketing is one of the serious problems which has probably been most neglected. In most of the territories both private and government marketing institutions undertake marketing of agricultural produce. In most cases staff has not been trained in Agricultural Marketing. It has been difficult to set up meaningful grades and standards which can be understood by the producer, and in most cases storage facilities are totally inadequate. Market Intelligence Services are virtually nonexistent and transportation within and between territories appears to be totally inadequate. If the trade in vegetables is to develop to significant proportions within the area, it is going to be necessary for a far more sophisticated approach to be made toward solving the entire marketing complex. In some territories harvesting equipment is being used, and some growers have established pauling houses, while others have constructed limited cold store facilities. Standards and grades which are meaningful to all the trading partners will have to be established.

This paper has identified several problems associated with the production of vegetables throughout the Commonwealth Caribbean. It can be seen that some territories appear at present to lack adequate facilities, staff, etc. and these naturally adversely affect systematic and reliable production of vegetables. It should be mentioned, however, that due to some inherent factors such as soils, climate, topography, rainfall pattern, large areas of level land, availability of irrigation facilities etc. some territories appear to have some comparative advantage over others for the production of some vegetable crops. It would appear as though serious consideration must be given to the rationalization of vegetable production within the Commonwealth Caribbean so that those areas best suited to the production of certain crops could be encouraged to produce some crops and supply other territories. Similarly, those same territories should be required to pur- chase vegetables not produced by them from the other territories. It is recognised, however, that this concept is much more easily advocated than implemented. However, if meaningful expansion is to take place within the area each territory competing with the other will probably do far more harm than good. - 18 -

SUMMARY

The Caribbean Free Trade Association was launched in 1968 and one of its functions was to stimulate and encourage agricultural production in the Commonwealth Caribbean area.

There are several factors operating against the systematic and orderly production of vegetables in the area. Some of these include identical policies of import substitution, more or less identical periods of production and seasonal gluts. The fact that Research is desirable and expensive, together with the fact that many areas are not endowed with a topography conducive to mechanized systems of production imposes certain restrictions on production.

Irrigation is virtually non-existent in some territories, while others lack adequately qualified staff and facilities. Financing is generally difficult. - 19 -

OBSERVATIONS ON THE CAUSES OF THE POOR COCONUT YIELD IN THE POMEROON, GUYANA

N. D. Singh!/

Coconuts are very important in Guyana for the production of vegetable oil, margarine, soap and waternuts. Unfortunately, coconut production not only in Guyana (1) but also in tropical America is severely restricted by diseases and pests (2). There is a high mortality of coconut palms before they attain the age of ten years in the Pomeroon riverian area. Economic losses and disruption in the past have been observed but in all instances the precise nature and extent of damage remained unknown.

This investigation was, therefore, undertaken to find out the causes for the low yield of coconut palms in this region. The information hitherto unabailable would, hopefully, provide the basis for research and control programmes.

MATERIALS AND METHODS

The coconut cultivation in the Pomeroon River extends to about 25 miles on both river banks. Twenty coconut trees were randomly selected for every one to one half mile on either river bank. Individual trees were then examined in the crown, stem and roots for disease symptoms, insect damage or presence of the palm weevil, Rhynochophorus palmarum L., which is a vector of the red ring nematode, Rhadinaphelenchus cocophilus Cobb. A core sample was taken at different heights of the coconut stem with a 3/4" auger and a power motor saw and examined for red ring symptoms.

Soils samples taken from around the roots of each red ring infected tree were processed and examined for R. cocophilus by Cobb's technique (4).

Free soil water level was taken at two positions per site at two different times, one at low tide and the other at high tide. The general condition of the site was also recorded including tree density, average age of trees and average production per tree per year.

RESULTS

Of the 320 trees examined, about 7.3 per cent were infected with red ring disease, 30 per cent with bud rot, caused by the fungus Phytophthora palmivora Butler and 6 per cent infected with other insects (Table 1).

The palm weevil was associated with red ring, seventeen out of the twenty-two cases. Only in one case was R. cocophilus found in the soil sample taken from a tree infected only in the root. Infected trees were

1/ University of the West Indies, Trinidad. - 20 - often found in groups in low-lying areas. Red ring disease incidence was almost absent in high sand reef and better drained areas (Table 1). Both root and top infection were observed together in only three trees out ot the twenty-two red ring infected trees.

About 30 per cent of the coconut trees between 3-15 years old were infected with bud rot. Bud rot infected coconut trees were found most frequently in poorly drained areas.

Several species of insects, (Strategus coleus F.) the large moth borer, (Castnia daedalus Cram.) and the rhinoceros beetle (Oryctes rhinoceros Linn.) were found in about 6 per cent of the coconut palms (Table 1). The Rhinoceros beetles were found to attack young palms 3-6 years old, whereas the other two insects also attacked older and larger trees.

Free soil water level varied between 4-18" and this level fluctuated by 0-16" with the rise and fall of the river.

DISCUSSION

The observations were made on growing plants randomly selected. Since dead plants were not examined, the cause of death cannot be stated with certainty. The observations primarily showed the proportion of coconut trees associated with the various diseases and pests.

Bud rot was observed in 30 per cent of the coconut palms examined. It seems the long hours of morning mist together with poor estate management created an ideal situation for disease spread.

Toxic soil conditions may be another factor contributing to the high death in coconut palm3. This area is known to have poorly drained organic soils with substrata of 'caty' material (5). The coconut palm requires well-drained soils Tor best growth (3). Poor drainage, as evidenced by the relatively high level of the free soil water, is undoubtedly a factor responsible for low nut production (45-55 nuts per tree per year) of the entire region on the left bank of the river. This is to be compared with the nearby well-drained, sandy reef areas where production is over 100 nuts per tree per year and disease and pest incidence is lower.

Management practices were found to be generally poor. Dead and severely diseased trees are not removed and certainly serve as sources of inoculum for the spread of red ring, bud rot and as attractants for pests.

There was evidence also of the lack of proper weed control and fertilizer programmes.

It can be concluded that red ring, bud rot, insect pests, poor drainage and poor management together contributed to the low coconut yield in the Pomeroon area. Table 1.—Number of coconut trees attacked by various pests and diseases in the Pomeroon River area

Red Ring, Red Ring Red Ring Red Ring Bud Rot Bud Rot Infected Kind of and and and and Bud Rot Insects Location Trees Infection Bud Rot Insects Insects Insects

1 - - 4 - - - - - 2 4 3 3 2 crown* 7 3 - - 1 - 4 - - 6 - - - - - 5 3 crown*5 9 3 1 1 1 1 Low lying c 6 1 root 9 - - - - - 7 - - 6 1 - - - - 8 3 2 crown'' 7 1 1 - 1 - 9 4 3 crown*5 1 root 9 3 1 1 2 1 Low Lying 5 0 3 crown' 9 1 1 1 - - Poorly drained 5 1 2 crown* 7 2 _ 1 Poorly drained 2 - - 2 1 _ _ _ Sandy reef 3 - - 6 _ _ _ 5 _ _ 4 4 3 crown* 7 4 1 2 2 1 Low lying 5 - - 4 - _ _ _ Sand reef 6 - - 3 - * _ _ _ _

22 97 19 a - 20 coconut trees were examined per site. b - weevil present in crown of coconut tree. c - Rhadinaphelenchus cocophilus present in soil sample. - 22 -

SUMMARY

The general low yield and crop failures of coconuts in the Pomeroon River region were found to be due to the combined damage from high water table accompanied with poor drainage, insect pests (Strategus coleus F., Oryctes rhinoceros Linn., Castnia daedalus (Cram.); bud rot (Phytophthora palmivora Butler) and red ring (Rhadinaphelenchus cocophilus Cobb.) diseases. Insect pests, bud rot and red ring diseases were present in 6, 30 and 7 per cent of the coconut palms respectively.

REFERENCES

1. Bissessar, S. Red Ring Disease in Guyana. Personal Communication, 1969.

2. Blair, G. P. Studies on Red Ring Disease of the Coconut Palm. Symposium on Tropical Nematology. Univ. of Puerto Rico. Nov. 29, 1967.

3. Child, R. Coconuts. London, Longmans, 1964.

4. Cobbs, N. A. Estimating the Nema Population of the Soil. Circ. Agric. Technol., Bur. PI. Ind. U.S. Dept. Agric. 1:47 p.

5. Ramdin, H. Technical Communication in File. "Development of Pomeroon River". Ministry of Agriculture, Guyana.

Department of Crop Science 28th May, 1971. Distribution of dry matter and mineral nutrients in tubers of two cultivars of Dioscorea alata L.

X. U. Ferguson, P. H. Haynes and J. A. Spencei'

The distribution of dry matter, energy, N, P, Ca, K, Mg and crude

protein were examined in the pulp and peel of two cultivars ('White

Lisbon' and 'Oriental') of D. alata L. Positive physiological gra-

dients in nutrient concentrations were observed. The concentrations

of dry matter, energy, N, P, Ca, Mg and crude protein decreased from

head to tail end of tubers; K was the only determinant to increase in

concentration from head to tail end of tubers. The concentrations of

K and Ca were higher while those of dry matter and N were lower in the

peel than in the pulp. The pulp and peel of bulbils were higher in

N, P and K and lower in Ca than the pulp and peel of whole tubers of

similar size. Crude protein content on a dry weight basis decreased

from head to tail end of tubers and was higher in the peel.

INTRODUCTION

The tubers of yams (Dioscorea spp.) are believed to be of stem origin and develop by the plagiotropic lobing of a degenerate rhizome (Burkill, 1960;

Martin and Ortiz, 1962). The region of growth of the tuber is distal to the aerial stem or vine. The part of the tuber proximal to the vine is therefore older and thus physiologically more mature than the distal region.

—' Faculty of Agriculture, University of the West Indies, St. Augustine, Trinidad, W. I. - 21* -

Physiological gradients have been demonstrated in tubers of the potato

Macklon and DeKock, 1967; Johnston et al., 1968), and the cocoyam (Xanthosoma sagittlfollum Schott) (Enyi, 1967). There is, however, little information on physiological gradients in yam tubers. Coursey (1967) noted that the head end of the tuber of yams is usually hard, woody and unpalatable. Miege (1957) found that the head and tail regions contain smaller starch grains than the middle region. Coursey et al. (1960) reported that the tail region of D. rotundata Poir. contains a markedly higher moisture content than the head end.

Martin and Thompson (1971) examined the crude protein (N x 6.25) content of

40 yam cultivars belonging to five species, and found that crude protein content varied 'rom 6.3 to 13.4 per cent on a dry weight basis. These authors reported crude protein values of 8.25 and 7.72 per cent from the unpeeled midsections of the D. alata L. cvs 'Farm Lisbon' ('White Lisbon') and 'Oriental', respectively. In the D. alata L. cv., 'Morado', it was found that crude protein content was highest in the upper (head) and inner portions of the tuber. The peel of the yam tuber consists of a corky bark and an immediately underlying cortex (Coursey, 1967). Oyenuga (1959) found that the peels of D. alata, D. rotundata, D. esculenta (Lour.) and D. cayenensis Lam. contain more crude and true protein, and thus nitrogen, than the rest of the tuber or pulp. Martin and Thompson (1971) also found a higher crude protein content in the peel of

D. alata (cv. 'Morado').

It was the purpose of this study to determine the content and distribution of dry matter, energy and nutrients in the tuber of D. alata using cvs

'White Lisbon' and 'Oriental'. - 25 -

MATERIALS AND METHODS

Three mature and dormant tubers weighing between 0.5 and 1.0 kg were selected from each cultlvar. They were divided into head, middle, and tail sections.

The sections were peeled with a sharp knife to a depth of about 2 mm. The portion so removed is hereafter called the peel. Samples of about 50 g were taken from the peeled portion (hereafter called the pulp). The peel from each section was taken as a sample. Samples from three small underground tubers and three bulbils (aerial tubers) of cv. 'White Lisbon', each weighing about 75 g, were similarly prepared. The peel from the small underground tubers and the bulbils were bulked as a single sample.

The samples were dried to a constant weight at 100°C and then ground.

A sample of 100 mg of the ground material was digested with sulphuric acid and hydrogen peroxide. Total N was determined on this digest by micro-Kjeldahl distillation, and total P by the chlorostannous-molybdate method in a sulphuric acid system (Jackson, 1958). For K, Mg and Ca determinations, a sample of 500 mg of the ground material was ashed in a muffle furnace at 450°C for several hours and the residue dissolved in weak hydrochloric acid. Ca and Mg were determined by atomic absorption and K by flame photometry. Energy values were determined on the pulp of the head, middle and tail sections only; they were determined by bomb calorimetry.

RESULTS

The data presented in Table 1 show that very large differences exist among individual tubers for some determinations. The error variances for these determinations were high and significant variance ratios were not always recorded although definite trends were observed. The differences between - 26 - tubers were sometimes higher than within tubers. Ca and P contents were the most variable determinants among tubers.

The distribution of dry matter, energy value and nutrients in the pulp and peel are presented in Tables 2 and 3, respectively. Dry matter percentage decreased from head end to tall end in the pulp of both cultivars. The head end had a significantly greater percentage dry matter than the middle and tail sections. There were small but Insignificant differences between the cultivars for percentage dry matter in the pulp. The peel had a lower percentage dry matter and differences between the head and middle sections were not as marked as those in the pulp. Compared with 'Oriental', the various sections of the peel of 'White Lisbon' had a more uniform and lower percentage dry matter content.

Table 1. Dry matter, energy and nutrient contents of three individual tubers of 'White Lisbon' and 'Oriental' yams. Mean values of head, middle and tall sections expressed on a fresh weight basis

'White Lisbon' 'Oriental'

Pulp:

Dry matter (7.) 24.9 25.3 20.4 25.2 23.2 24.2 Energy (J/g) 3587 3818 3022 3755 3437 3541 N (mg/100 g) 283 448 227 420 256 360 P (mg/100 g) 35.3 38.4 28.3 49.5 12.4 28.3 K (mg/100 g) 312 317 384 356 165 280 Ca (mg/100 g) 9.5 34.9 15.4 13.7 32.5 27.6 Mg (mg/100 g) 23.0 24.6 18.7 16.9 16.6 16.7

Peel:

Dry matter (%) 18.4 16.3 15.1 21.4 19.2 16.5 N (mg/100 g) 257 301 208 409 297 349 P (mg/100 g) 32.4 31.7 23.1 38.7 26.9 23.8 K (mg/100 g) 365 329 370 432 302 434 Ca (mg/100 g) 90.5 205.9 96.1 63.3 131.0 100.0 Mg (mg/100 g) 28.7 24.4 28.6 23.9 24.9 19.7 - 27 -

Table 2. Distribution of dry matter, energy and nutrients in the pulp of tubers of 'White Lisbon' and 'Oriental' yams (means of three tubers)

Dry Fresh Dry Section (7.) Cultivar wt. wt. N P K Ca Mr

'White Head 30.5 4584 14990 520 44.. 3 238 36.9 31.0 Lisbon' Middle 20.3 2997 14831 251 28.. 5 277 14.3 22.3 Tail 19.7 2846 14458 190 29.. 2 308 8.5 13.0

'Oriental' Head 33.3 4981 14978 517 33.. 6 251 47.5 21.5 Middle 21.3 3098 14538 271 27.. 0 286 17.8 17.0 Tail 18.0 2654 14701 215 27,. 0 297 8.6 11.7

SB 2.33 352 197 75 9.. 5 40 10.9 4.4 CV(7.) 16.9 17.2 2.2 39.7 51.. 4 25.1 32.5 39.2

Table 3. Distribution of dry matter and nutrients in the peel of tubers of 'White Lisbon' and 'Oriental' yams (means of three tubers)

Dry Nutrient (mg/100 g fresh wt.) Cultivar Section matter (7.) N P K Ca Mg

'White Head 16.5 316 30.9 323 167.4 30.5 Lisbon' Middle 16.3 236 28.0 358 130.0 27.2 Tall 16.9 215 28.3 383 95.2 24.0

'Oriental' Head 20.7 412 35.1 364 106.7 25.2 Middle 18.5 352 27.9 410 89.3 18.9 Tail 18.6 312 26.4 394 98.3 23.5 SB 1.44 34 4.5 38 33.6 2.5 CV (7.) 14.0 19.3 26.4 17.5 50.9 17X5

Like dry matter, the energy content of the fresh tuber decreased from

head end to tall end (Table 2). When expressed on a dry weight basis the

energy content was also highest in the head section but differences were not

significant. Similar energy contents were recorded for both cultivars. - 28 -

The contents of N, P, Ca and Mg decreased while the content of K In- creased from head to tail in the pulp and peel of both cultivars. N content of the pulp was 2.7 and 2.4 times higher in the head than in the tail sections of 'White Lisbon1 and 'Oriental* respectively, indicating that a definite N gradient exists in the yam tubers studied. There was a similar

N gradient in the peel but differences between sections were not as great.

The gradient for P was not as marked as that observed for N, the P concentration In the pulp of the head section being only about 1.5 and 1.2 times higher than those in the tail sections of 'White Lisbon' and 'Oriental', respectively.

Ca content had the most marked gradient along the tubers. In the pulp of

'White Lisbon' it was 4.3 times higher in the head than in the tail section and in 'Oriental' it was 5.5 times higher. The Ca content of the peel was very much higher than that of the pulp. The Ca content of the peel in the tail section of both cultivars was more than 11 times greater than in the pulp of the tail section in both cultivars; but in the head section the Ca content was only 4.2 and 2.2 times greater in the peel of 'White Lisbon' and 'Oriental', respectively. Mg content in the pulp of the head section of 'White Lisbon' was 2.4 times higher and in 'Oriental' was 1.8 times higher than the tail sections. In the peel the Mg gradients were not as marked. Similar Mg contents were recorded in the pulp and peel of head and middle sections In both cultivars, but in the tail section Mg content was much higher in the peel.

K was the only nutrient to increase in content from head end to tall end. In the pulp of 'White Lisbon' it was 1.3 times greater in the tall than in the head section and in 'Oriental' it was 1.2 times greater. The K content was higher in the peel than in the pulp and the gradient in the peel was similar to that described for the pulp. - 29 -

The dry matter and chemical composition of bulbils and small tubers of

'White Lisbon' are given in Table 4. The dry matter content and chemical

composition of the small tubers were very similar to those observed in the

middle section of the larger 'White Lisbon' tubers. The pulp and peel of

Table 4. Mean dry matter and nutrient content in the pulp and peel of three small whole tubers and three bulbils of 'White Lisbon' yam

Dry Nutrient (mg/100 g fres'n wt.) Tissue matter (%) N P K Ca Mg_

Small whole tubers:

Pulp 21.9 282 26.5 281 19.8 17.0 Peel 17.8 283 19.4 365 148.3 23.9

Bulbils:

Pulp 30.9 360 33.9 342 9.5 17.6 Peel 21.2 456 30.5 498 39.0 33.5

bulbils had higher N, P and K contents than small tubers. The greatest dif-

ference between bulbils and small tubers was in Ca content, which was very much lower in bulbils. Ca content in the pulp of small tubers was more than

twice as high as in the pulp of bulbils and in the peel it was almost four

times greater.

Crude protein contents were calculated from the N values and are presented

in Table 5 on a fresh and dry weight basis. The trends for crude protein on

a fresh weight basis are similar to those discussed for N above. On a dry weight basis the crude protein content of the pulp in the head section was

1.7 and 1.3 times greater than that of the tail section in 'White Lisbon' and

'Oriental' respectively. The peel had higher crude protein on a dry weight -'30 *

basis than the pulp In all three sections of both cultivars. Bulbils had a

very high crude protein content on a dry weight basis in both the pulp and

peel.

Table 5. Percentage crude protein content (N x 6.25) of the pulp and peel in head, middle and tail sections of tubers, and of whole small tubers and bulbils of yam cvs 'White Lisbon' and 'Oriental'

'White Lisbon' 'Oriental'

Pulp Peel Pulp Peel

Dry weight basis

Tuber section:

Head 10.19 12.00 9..6 9 12.50 Middle 8.06 9.12 8,.9 4 12.06 Tall 6.06 8.00 7..3 1 10.81 Small whole tubers 7.93 9.87 — — Bulbils 11.25 13.44 — —

Fresh weight basis

Tuber section:

Head 3.25 1.97 3,.2 3 2.57 Middle 1.57 1.47 1..6 9 2.20 Tail 1.19 1.34 1..3 4 1.95 Small whole tubers 1.76 1.77 — — Bulbils 2.25 2.85 —

DISCUSSION

The higher dry matter content of the head section over middle and tail sec-

tions of tubers from both cultivars of I). alata studied matches observations made by Coursey et al. (1960), who noted that the head end of tubers of D.

rotundata contained a lower moisture content.

The tail end of the tuber is the region of greatest growth during tuber

development, and tissue in this region can be considered to be physiologically - 31 - leas mature than tissue from the head end. Lower dry matter content has been observed In the physiologically younger sections of the corm of the cocoyara (Enyi, 1967) and the tuber of the potato (Johnston et al., 1968).

The difference In percentage dry matter between the mature and younger sections, however, appears to be greater for yams than for either cocoyam or the potato. Enyi (1967) observed a difference of seven per cent for coco- yams and Johnston et al. two per cent for the potato, whereas we found that the difference for 'White Lisbon' is about 11 per cent and for 'Oriental' about 15 per cent. This may also indicate that the yam tuber has greater physiological differences between mature and young sections than either the corm of the cocoyam or the tuber of the potato.

The results indicate that definite nutrient gradients exist in the tuber for the five nutrients determined. The content of N, P, Ca and Mg decreased from head to tail whereas K content appears to be highest in the tail section. Setts taken from the head section thus have a greater reserve of N and P which are important for root and shoot development in the early stages of growth. Furthermore, the higher dry matter and energy contents indicate a greater potential for the supply of carbohydrates from setts of the head section for the development of the young plant.

The higher concentration of K in the tall section is interesting from the point of view of K as a nutrient for mobilizing assimilates. Fujise and

Tsuno (1967) demonstrated that high levels of K in the young tubers of sweet potato are necessary for good yields. These two workers put forward the hypothesis that K acts to Increase the E^ON ratio in the tuber. This leads to an increase in the water content of the tuber, a faster respiratory rate and increased relative growth rate. The outcome is speedier translocation - 32 - of photosynthates from the leaves. In the tail section of the yam tuber high K and low N ensure a high K/N ratio. Also, in this section the moisture content is higher. These factors could be related to the mobilization of assimilates into the tail section which is the region of growth of the tuber.

In the cocoyam where the region of growth is the top of the corm (proximal to the leaves) , the data of Enyi (1967) indicate that the K/N ratio decreases from the youngest to the oldest section (Table 6). The data of Johnston et al. (1968) indicate that the K/N ratio decreases from bud to stem end in the

Table 6. Effect of age of sections on the K/N ratios and percentage moisture content in the tubers of yam and potato and the corm of cocoyam

Yam* CocoyanH- Potatot 'White Lisbon* 'Oriental' Section Moisture Moisture Moisture Moisture K/N content K/N content K/N content K/N content

Oldest 0.46 69.5 0.48 66.7 1.31 80.0 0.90 77.8 Youngest 1.62 80.3 1.38 82.0 1.35 87.2 1.16 79.8

* Data from the pulp of the two cultivars of D. alata studied herein. + From Enyi (1967). + From Johnston et al. (1968). potato tuber. Macklon and DeKock (1967) found no gradient for nitrate in the potato but observed that K was much higher in the bud end. This can be inter- preted to mean that in the potato the K/nitrate ratio was higher in the bud end which is the region of growth of the tuber during the early stages of tuber development and physiologically the youngest section. Moisture content was also higher in the youngest section of both the cocoyam corm and the potato tuber (Table 6). There thus seems to be a common pattern in the tubers or corms - 33 - of these root crops with high K/N ratios occurring in the youngest section; this pattern lends support to the suggestion of Fujise and Tsuno (1967) that a high K/N ratio may help in the movement of assimilates to a developing area.

The value of 8.25 per cent crude protein (on a dry weight basis) reported by Martin and Thompson (1971) for the unpeeled sections of 'White Lisbon' tubers in Puerto Rico compares favorably with the 8.06 per cent we found in the middle section of peeled 'White Lisbon' tubers. The peel, which constitutes only a very small part of the tuber, has a higher crude protein content (dry weight basis) and the value of 8.06 per cent would have been slightly higher had the middle section not been peeled. The crude protein content of

8.94 per cent (dry weight basis) in 'Oriental' was, however, higher than the value of 7.72 per cent reported by Martin and Thompson (1971). The crude protein content (dry weight basis) in tubers was higher in the peel and decreased from head to tail and confirms indications noted by Martin and

Thompson (1971) in tubers of JD. alata cv. 'Morado' . The high crude protein content of bulbils suggests that where they are produced in large quantities they may be considered for use in livestock rations.

ACKNOWLEDGEMENTS

The authors wish to acknowledge the help of the Department of Soil Science,

U.W.I, and Miss Ingrid Ammon in the analysis of samples. This work was sup- ported by a grant from the Rockefeller Foundation. - 34 -

REFERENCES

Burkill, I. H. (1960). 'The organography and the evolution of Dioscoreaceae, the family of yams'. F. Linn. Soc. London (Bot.) 56, 319-412.

Coursey, D. G. (1967). Yams. Longmans, Green, London.

Coursey, D. G., Nwankwo, F. I. and Enyenlti, L. V. (1960). 'The distribution of moisture in yams'. Rep. West Afr. Stored Prod. Res. Unit, Lagos.

Enyi, B. A. C. (1967). 'The effects of age on establishment and yield of cocoyam setts (Xanthosoma saRittlfolium Schott)'. Exp. Agric. 3, 121-127.

Fujise, K. and Tsuno, Y. (1967). 'Effect of potassium on dry matter production of sweet potato'. Proc. 1st. Int. Symp. Trop. Root Crops 1, 11-20, 29.

Jackson, M. L. (1958). Soil Chemical Analysis. Prentice Hall, Englewood Cliffs, N.J.

Johnston, F. B., Hoffman, I. and Petrasovits, A. (1968). 'Distribution of mineral constituents and dry matter in the potato tuber'. Am. Potato J. 45, 287-292.

Mncklon, A. E. S. and DeKock, P. C. (1967). 'Physiological gradients in the potato tuber'. Physiol. Plant. 20, 421-429.

Martin, F. W. and Ortiz, S. (1962). 'Origin and anatomy of tubers of Dioscorea florlbunda and D. spicullflora'. Bot. Gaz. 124, 416-421.

Martin, F. W. and Thompson, A. E. (1971). 'Crude protein content of yams'. Hortic. Sci. 6, 545-546.

Miege, J. (1957). 'Influence de quelques caracteres des tubercules semences sur la lev6e et le rendement des ignames cultlvges. F. Agric. Trop. Bol. Appl. 4, 315-342.

Oyenuga, V. A. (1959). Nigeria Feeding Stuffs. Ibadan University Press, Ibadan, Nigeria. - 35 -

SOME PROBLEMS INVOLVED IN THE PRODUCTION OF VEGETABLES IN THE COMMONWEALTH CARIBBEAN

W. deCourcey Jeffer3±'

This paper attempts to identify some of the more serious problems affecting Vegetable Production in the Commonwealth Caribbean.

The Caribbean Free Trade Association (Carifta) come into being during 1968. Provision was made for an Agricultural Marketing Protocol designed to stimulate, encourage and permit a greater volume of trade in agricultural commodities, including vegetables within the Commonwealth Caribbean area.

In some of the Commonwealth Caribbean territories one-crop economies existed e.g., Montserrat, Cotton; St. Kitts, Sugar Cane; Barbados, Sugar Cane; St. Vincent, Bananas. In those islands growing sugar cane and cotton in particular, it became obvious that because of marketing and other problems it was very necessary to diversify their agriculture. With just about all of the Commonwealth Caribbean territories concentrating on developing a tourist industry, it was also seen fit to produce much more local products and therefore import less. It is seen therefore that most, if not all, of the Commonwealth Caribbean territories had more or less the same motives for diversifying their agriculture^ and later they tended to have identical objectives of import substitution.

One of the problems encountered in the production of vegetables in the Commonwealth Caribbean is the fact that growing seasons tend to be more or less identical. It is not uncommon therefore to find when there is a glut in one territory of a particular crop, the same is very often true in many of the other territories. This inevitably frustrates marketing particularly since vegetable crops by and large are highly perishable and storage facilities could hardly be considered as ideal or adequate in many territories. What is snid of gluts is also true of scarcities, and very often produce has to be imported from the U.S.A. and Canada.

Agricultural Research is expensive. It is very often felt that Research work can be carried out at a central place within the area and the results applied throughout. This might be theoretically true but does not work out in practice, and therefore leads to repetition and duplication. Many of the Commonwealth Caribbean territories are not adequately staffed to do the volume and type of Research on Vegetable Crops that is necessary. Some territories, therefore, have considerable advantage over others from a research standpoint.

1/ Ministry of Agriculture, Science & Technology, Bridgetown, Barbados, W. I. - 36 -

SOME INFORMATION ABOUT PEASANT RICE FARMING IN NICKERIE (SURINAME)

R. E. DumasU

INTRODUCTION

Rice is the most important crop of Surinam in terms of both area and export value. In 1968 of the total area under cultivation, about 47,000 ha, nearly 75% was occupied by rice.

The rice-growing area is situated on the coastal plain consisting of young and therefore fertile clay soils (60-90% clay). Under natural circumstances this area is characterized by the presence of swamps.

The totai value of agricultural produce in 1968 amounted to Sf 37.6 million, rice contributing Sf 17.7 million of which Sf 9.9 million were obtained from export (31,858 tons).

In 1968 a total area of 35,273 ha produced 115,626 tons of paddy which amounts to an average yield of 3,280 kg/ha. Of the area 71% waa situated in Nickerie, the most Western district of the country, supplying 76% of the total output.

General

Since 1965 peasant farming in the Nickerie district produces more paddy than all other districts together. In 1968 the contribution of the peasant farmers in this district to the total production was about 30%, while that of the other districts amounted to about 24%. The contribution of the Wageningen rice scheme was 36%. The following table shows the distribution of the Nickerie rice area and the productions in 1968.

About 45% of the number of peasant holdings is smaller than 2 ha, while 30% and 20% of the farms are in the class of 2-4 and 4-8 ha, respectively. These farms are owned by Hindustans (62%), Javanese (30%) and Creoles (8%).

The area has a reasonably satisfactory irrigation system, which obtains its water from the Nanni swamp. During the major season (April/May - Aug/Oct) there is sufficient water for all farmers. During the minor season (November- April), however, the water supply is inadequate to enable every farmer to grow a crop.

Tillage

Xhe Nickerie farmer tends to pay much attention to the cultivation of his land. Dry-tillage is highly valued. The field is usually dry-cultivated

1/ Rice agronomist at the Agricultural Experiment Station, Paramaribo, Surinam. Area (ha) Production Major Minor Major season Minor season Total Average season season Total tons kg/ha tons kg/ha tons kg/ha

Peasant farming 8.722 2.035 10.757 28,521 3,270 6,614 3,250 35,135 3,270

Large-scale farming* 7,705 6,622 14,327 28,662 3,720 23,692 3,580 52,354 ^,650

Total 16,427 8,657 25,084 57,183 3,480 30,306 3,500 87,48? 3,490

* including medium-sized (24ha) farms. - 38 -

twice, after which puddling is adopted as a last operation. The disc-plough and disc-harrow are the most used implements. The weather, however, is decisive as to the number of dry-cultivations possible, especially when two crops are grown per year. Up to now the farmers have paid little attention t'j the levelling of the field, which is important in the case of direct sowing.

Rice varieties

The assortment of rice varieties in Surinam consists of a number of traditional varieties and of SML*-varieties, the latter especially developed for mechanized cultivation. The old rice varieties such as Skrivimankoti, which are transplanted, have a growth duration of over 160 days. They have drooping leaves and are very susceptible to lodging. The grains are medium or long sized and have a good milling quality. When sown directly, most SML-varieties have a growth duration of 135-145 days, but when transplanted it takes 150-160 days for them to mature. They are characterized by erect leaves and extra-long grains. The SML-varieties are very high yielding and do not lodge easily. Their extra-long grains, however, break easily when not carefully treated. In order to be able to carry out a satisfactory land preparation, a growth duration of about 140 days is too long for Surinam conditions if two crops are to be grown per year. A further disadvantage of these SML-varieties is their plant height, not only affecting lodging but also the disposal of the straw after harvesting. At the rice breeding station of the SML, in the Prins Bernhard polder, several years work has been done on the development of varieties with a shorter growth duration and shorter straw. Recent three early maturing (105-120 days) varieties with short sturdy stems have been released. The extra long grain and the good yielding capacity of the "old" SML-varieties have been retained. Although the necessary experience with these varieties still has to be gained, it can already be stated that when growing these varieties, certain cultivation measures will require extra attention.

Transplanting - direct sowing

Following the example of the Wageningen rice scheme an ever increasing number of farmers have changed over to direct sowing. It is estimated that in the major season about 50% of the area cultivated by peasant farmers is sown directly. In case of continuous heavy rains at the beginning of the season the farmers tend to fall back to the transplanting method. The majority of the farmers (60%) grow SML-varieties. For those farmers who transplant, the variety Skrivimankoti is still a favourite. The rice is •50-jii onto slightly stiffened mud using seed quantities of about 120 kg/ha. On the large mechanized farms 90-100 kg/ha is used. Prior to sowing the seed is pregerminated and subsequently broadcast by hand. At a later stage the empty patchps in the field are filled in with plants from places with too close a stand.

*SML « Foundation for the Development of Mechanized Agriculture in Surinam. - 39 -

Weed control

The need to control weeds i3 more apparent with direct sowing than with transplanting. Many fanners who have changed over direct sowing still are not sufficiently aware of this. Though the noticeable recent increase in the sales of herbicides and spraying equipment is an indication that the farmers are going in the right direction, the importance of this cultural measure needs constant emphasis. Field trials have shown that a correct weed control results in average yield increased of about 20%. Most weeds can be controlled with 2,4-D and propanil.

Fertilizer use

The rice in Nickerie is fertilized exclusively with nitrogen (urea). Though there are indications that there is some need for phosphate, further research will have to confirm this.

Fertilizing with nitrogen was quickly adopted by the farmers in Nickerie. According to the fertilizing schedule used until recently at the Wageningen rice scheme, nitrogen was to be applied at three stages:

during tillering (40-45 days after sowing) during panicle initiation (60-65 days after sowing) during flower differentiation (80-85 days after sowing)

The total quantity amounts to 120-180 kg urea/ha, split about equally over the three dressings. Now the fertilizing schedule is more detailed. Field trials in the peasant rice polders have shown that the "old" fertilizing schedule may result in yield increases of 500-1000 kg/ha for the first two dressings and about 400 kg/ha for the third. The third dressing was only introduced in 1968 but so far has not been adopted by many farmers. Most farmers fertilize twice, and some only once. There is considerable variation as to the quantity and division of the total amount of the fertilizer as well as to the stages at which it is applied. Fertilizer management can still be improved on. Urea is being broadcast by hand onto a drained field.

Pests and diseases

Until now Helminthosporium oryzae is the most widespread disease. Since this fungus is generally considered as a weak-parasite optimal cultural measures are being recommended as a preventive control.

Snails (Pomacea lineata, Pomacea glauca), caterpillars (Laphygma frugiperda) and seedbugs (Oebalus poecilus) are pests which appear season after season and are the main threat to the farmer's rice crop. In general, farmers are willing to control pests because they cause visible damage. It appears, however, that there is some need to stress proper timing as well as the importance of co-ordinated control measures. The realization of the last point will not be easy since the Nickerie rice farmer is rather individualistic. Another problem is, that following the example of the Wageningen rice scheme and the medium-sized farms, the peasant farmers also have started to use poisonous chemicals. Since the water of the rice fields - 40 -

is sometimes drained into irrigation canals the water of which is being used for laundry (sometimes even for drinkwater), it will be clear that public health might be seriously endangered. Soon, however, a pesticide ordinance is expected to come into force.

Harvesting

Harvesting is done mainly mechanically. As with cultivation operations, contracting machinery for harvesting is an increasing practice. In the Nickerie district there are 47 combines which means that if the harvesting period is 2 1/2 months, during the autumn-harvest each combine must to about 3 ha a day. Still a shortage of combines was noticed during the ^yrurnn-harvefts of 1969 and 1970. The cause of this can be attributed to too small a spread of the harvesting period, the state of repair of the combines, lodging of the crop, heavy weed growth on a number of farms and the quite considerable distances between farms.

It must be stated that the timely harvest and drying of the paddy is essential to obtain a good quality. Many a farmer wants to harvest early because at that time the prices are higher than later in the season. In order to achieve this the field is often drained too early which means the crop is forced to ripen. It is clear that this unfavourably affects yield and quality.

At the moment the available drying-capacity in Nickerie is 43 tons/ hour. Under the present conditions this is insufficient, which is once more attributed to the small spread of the harvesting period. The buying-up of the paddy and the drying equipment are mainly in private hands. For a number of reasons many farmers are selling a considerable part of their crop before harvest to such a merchant.

Water management

With the present system of farming, where direct sowing is used, the water management is fairly complicated. During the growing season the fields have to be flooded and drained several times, which means a waste of water since the drainage is not pumped back into the irrigation canal. Other causes of the waste of water can be attributed to a lack of a clear supervision of the water use. In order to use the irrigation water as efficiently as possible serious attention will have to be paid in the near future to the cultural methods and to the supervision of the irrigation system. At present water shortage is restricted mainly to the minor season so that not every farmer can grow a second crop. Since the interest in a second crop is on the increase the need for sufficient water becomes more urgent. At the moment the water level in the irrigation canals during the minor season is brought to about 10 cm below ground level so that a water- pump is virtually essential to the farmer.

Other aspects

The income of the smallholders is low because it is largely determined by the size of the firm. Moreover it fluctuates with yields and prices. - 41 -

Many youngsters, therefore, are leaving the farms whilst most of the Nickerie farmers are looking for off-farm work in order to increase their income. Part-time farming probably also promoted by the increasing mechanization, is an important aspect of peasant rice farming in Nickerie. Also because of the considerable population growth unemployment is quite a thorny problem.

A further point is that the peasant farmer is presently very dependent on the private rice buyer, who normally owns the drying and processing equipment. With their method of buying there is no incentive for the farmer to improve on the quality of this product.

Although at the moment the total output of peasant farming still does not cover home consumption, it is to be expected that in the future one has to reckon with an increasing quantity for export. In this connection it is interesting to note that presently, in cooperation with Dutch experts, a plan is being prepared to efficiently transmit to the farmers all that is known about rice growing in Surinam.

SUMMARY

Nickerie is the most important rice district of Surinam. The majority of the rice growers have small farms which provide an insufficient income so that part-time farming is widely practiced. The progress in peasant rice farming, due to the presence of medium-sized and of large rice farms and the existence of a reasonably satisfactory irrigation system, is marked by the use of improved varieties, the switch to direct sowing, the increasing interest in growing two crops per year and the degree of mechanization. Several cultural practices can still be improved on. Extension work is being stepped up. Several other measures should be taken to promote a sound development of the rice industry.

Du/JS - 42 -

VEGETABLE CULTIVAR SCREENING TRIALS 1970 - 1971, A PROGRESS REPORT

F. L. Roach, R. M. Hoad, W. Headley, M. T. Burke and B. W. Eavisi/

Cultivar selection is the most promising means of rapidly improving yields and quality of vegetables grown in the Caribbean. In Barbados during 1970-1971 a large number of cultivars of onions, carrots, cabbage, snap beans, beetroot, lettuce and radish were screened as part of the joint Ministry of Agriculture, O.A.S. Vegetable Research and Development Programme. Certain cultivars were selected for further trials in larger plots under semi-commercial conditions, and the most outstanding ones will be finally stocked by the Ministry of Agriculture seed store. Only initial screening trials are described in this paper since the final selections from second stage trials are not yet complete.

In the preliminary screening trials cultivars were evaluated chiefly on physical characteristics, though in some cases yield was also determined. Many of the trials will be repeated at different times of the year so that seasonal effects may be examined.

Onions;

Two trials were carried out; the first was planted on 11th - 12th June 1970 and the second on 7th - 8th January 1971.

The following cultivars were used:

Dessert Seed Co: Granex, Henry's Special, Dessex, Early Premium, Golden, Y 28, Early Harvest, Spano, White Alamo Hybrid, Robust, Majesty, Peerless, Red Granex, Tropicana, Early Grano, Early Top, Texas Early Grano 502, San Joaquin Excel 986, Yellow Creole, Yellow Bermuda, Stockton Yfllow Globe, Imperial 48, Early Crystal 281, White Mexican, White Creole, White Queen, Red Creole C5, Burgundy, Calred, California Early Red, Red Grano, Colorado It6, Dehydrator #3, Dehydrator l?4, Dehydrator #6, Dehydrator #8.

Niagara Seed Company: Early Texas White Grano, Excel 986 Yellow, Red Creole C5, Granex Yellow Hybrid.

Keystone Seed Company: Crystal Wax, Excel 986, Red Creole C5, Texas Early Grano 502, Fiesta, Granex Yellow PRR F1 Hybrid, Sweet Spanish Utah Jumbo Yellow.

X randomized block design with three replications was used and the plot size was 192 sq. ft.

1/ Ministry of Agriculture, Science & Technology, Bridgetown, Barbados, W. I. - A3 -

The cultivars were evaluated on 21st August when most of the "pickling" types were maturing, and again for the remaining cultivars at the end of September. Characteristics assesses were shoot and bulb development, bulb size, shape and colour and average weight of bulbs.

It was decided that all cultivars would be tried again at different times of the year because of the effects of daylength and temperature on bulb formation. The best selections from this trial were:

Best full size Yellow: Granex Yellow PRR F1 Hybrid (Keystone), Granex Yellow Hybrid (Niagara), Granex (Dessert), San Joaquin (Dessert), Early Top (Dessert).

Best full size Red: Red Granex (Dessert), Burgundy (Dessert).

Best full size White: Early Texas White Grano (Niagara)

Best yellow pickling size: Y 28 (Dessert), Golden (Dessert).

Best white pickling size: White Queen (Dessert), White Creole (Dessert).

In the second screening trial, planted in January, the same full size yellow cultivars were selected with Texas Early Grano (3, 5) and Dessex (3) as additions. Four Japanese hybrids f rom the Takii Seed Company, Dragon Eye, Express Yellow, Trial No. 5 and Keep Well were included in this trial. These started to bulb much later than Granex (3) and at the present time are not sufficiently dieveloped to evaluate.

During 1970-1971, Granex Yellow PRR F1 Hybrid (5), and Yellow Granex F1 Hybrid (3) were the main cultivars used in the 153 acres of onions planted during September to November. Although the yields are excellent, skin retention is very poor and it crushes easily on pallets during ship- ment. Losses due to reshooting during storage have also been a problem. It is now planned to compare Dessex, Early Top and San Joaquin with Granex in commercial trials. Dessex forms smaller bulbs than Granex when planted in June or January but may be suitable for early planting in September. It may have beeter skin retention and seems to be more uniform with less loss through thick necks. Early Top and San Joaquin are similar in appearance and shape to Texas Early Grano but plant to plant uniformity is better. Crushability, storage characteristics and disease resistance will be considered in the second stage trials.

Excellent pickling cultivars are now available as a result of these trials, and June seems a favourable month for planting; bulbs are mature within eight weeks.

Carrots:

This trial was planted on 25 th June 1970. Planting at this time of the year does not give the quality and yield of carrots which can be expected from September to January plantings and the characteristics of cultivars may vary with season. It will therefore be necessary to repeat this trial at different times of the year. The following cultivars were used:

Burpee Seed Company: Popsicle

Asgrow Seed Company: Highlight

Dessert Seed Company: Hybrid F1 Gold, Hybrid F1 Imperator 286, Hybrid F1 Chantenay 9532, Wisconsin It5, Hybrid F1 Early Cross.

Vaughan Seed Company: Sweethear

Sutton & Sons: Champion Scarlet Horn, Early Gem, Concord, Favourite New Red Intermediate.

Northrup King Seed Company: Pacesetter, Danvers Half Long Red Cored Touchon.

Ferry Norse Seed Company: Gold Pale, Chantenay Red

Ohlsens Enke: Nantes Empire Osena, Amsterdam 378 Osena, Nantes Express Osena, Amager Osena, Flakkeer Giant, Autumn Giant, Berlicum, Fancy Osena Novelty, James Scarlet Intermediate, London Market, Nantes Ny Munkegaard 11 Osena, Paris Market, Red Giant, Red Winter, St. Valery, Nantes No. 1003, Scarlet Horn, Regal Osena.

Niagara Seed Company: Industry, Nantes, Scarlet St Sr.

Keystone Seed Company: ' Chantenay Red Core No. 5, Chantenay Long No. 403, Chantenay Royal No. 13, Danvers 126, Eureka, Gold Pak 61, Imperator 58, Imperator Extra Long, Nugget, Touchon, Waltham Hicolor, Touchon.

A randomized Block design with 3 replications was used, and the plot size was 50 sq. ft.

The cultivars were evaluated at harvest at the end of October (four months after planting). Characteristics assessed were length, shape and colour, flavour and internal characteristics of the tissues, condition of the crown, plant to plant variability, susceptibility to infield rotting, and yield.

The best cultivars from June planting were: Chantenay Red Core No. (Keystone), Favourite (Suttons), Danvers Half Long Red Cored (Northrup Ring), Concord (Suttons), Early Gem (Suttons).

'Due to late delivery of seed, it was not possible to include Japanes cultivars from the Takii Seed Company. These will be included in future trials.

The same cultivars obtained from different seed companies varied considerably and it may prove necessary to examine in more detail strains within cultivars. - 45 -

All the above cultivars were medium long types with the exception of Early Gem which is a stump rooted type. Since the stump rooted cultivars are better suited to mechanical harvesting, it would be more convenient to grow them, provided that they are acceptable to the consumer.

To grow the long rooted carrots, special attention must be given to deep cultivations. The length of medium long carrots also is greatly improved by deep tillage.

Cabbage:

Seedlings were raised in boxes from 27th August sowing, and were transplanted in the field on 19th October 1970.

The following cultivars were used:

Asgrow Seed Company: Copenhagen Market, Headstart, Savoy Perfection Frumhead.

Ferry Morse Seed Company: Dutchman, Great Dane Y.R., Headmaster, King Cole, Little Rock, Roundup, Superette, Resistant Golden Acre, Bonanza, Ferry's Round Dutch, Globelle TBR, Ferry's Hollander, Oakview Ballhead, Wisconsin Ballhead Improved, Savoy Chieftain.

Burpee Seed Company: Earliana, Emerald Cross Hybrid, All Head Early Burpee, 0-S Cross, Succession.

Vaughan's Seed Company: C-C Cross, Stonehead Hybrid, Harvester Queen.

Northrup King Seed Company: American Drumhead Savoy, Hollander Short Stem.

Sutton S^ Sons: May express, Earliest, Favourite, Pride of the Market, April, Harbinger, Flower of Spring, Imperial.

Dessert Seed Company: Hybrid F1 Early Cross, Hybrid F1 Early Shipper, Dessert's 126, Green Acre, Badger Belle.

Niagara Seed Company: Badger Market Y.R., Copenhagen Market Eariy, Jersey Queen Y.R., Jersey Wakefield Early, Louisiana All Year, Brunswick, Penn State Ballhead, Wisconsin Golden Acre.

Keystone Seed Company: Badger Ballhead, Charleston Wakefield, Copenhagen Market II53, Dark Green Savoy, Early Glory, Early Round Dutch, Globe 62 MYR, Glory of Enkhuizen, Golden Acre, Greenback YR, Wisconsin Golden Acre, Marion Market YR, Premium Late Flat Dutch, Ventura, Stein's Flat Dutch, Wisconsin Hollander 98 YR.

Takii Seed Company: C-M Cross, C-G Cross, Express 50, C-0 Cross 69, C-M Cross 70, K-K Cross, Express Cross 60. - 46 -

A randomized Block design with 3 replications was used, and the plot size was 50 sq. ft.

The cultivars were evaluated on 15th December 1970, two months after transplanting and 3 1/2 months after sowing. Characteristics judged were size, colour, shape and compactnesss of head, plant to plant variability and characteristics of wrapper leaves.

The following cultivars were outstanding: Emerald Cross Hybrid (Burpee), Stonehead Hybrid (Vaughan), Express Cross 50 (Takii), C-0 Cross 69 (Takii), C-M Cross 70 (Takii), K-K- Cross (Takii), Express Cross 60 (Takii).

K-K Cross is also sold as Summer Stride, and C-M Cross as Emerald Cross Hybrid. In commercial plantings K-G Cross (Summer Pride) has also given good results.

Many of the cultivars which were not hybrids, were very variable. Bursting of the heads was also a problem, e.g. Early Jersey Wakefield. Size and shpae of head varied considerably between the different hybrids and further trials are necessary to assess yield, market acceptability, disense resistance and ability to store.

Introduction of some of the above cultivars through the Ministry Seedstore should greatly improve the quality of cabbage sold in Barbados.

Snap Beans:

This trial was planted on 4th and 5th November 1970. The following i'.ultivars were used:

Ferry Morse Seed Company: Burpee's Improved Bush, Fordhook Bush 242, Henderson's Bush, Jackson Wonder Bush, Thorogreen Early, Avalanche, Broad Improved Long Pod, Bush Romano 14, Green Lakes 5A, Processor, Tenderette, Fordhook Cone. 242.

Keystone Seed Company: Bountiful, Bush Blue Lake 274, Cascada, Catskill RB 4, Commodor Improved, Contender, Corneli 14, Earliwax, Extender, Gallatin 50, Harvester, Mountaineer, Olympia, Provider, Resistant Cherokee Wax, Resistant Kingshorn Wax, Slenderwhite, Slimgreen, Taylor Horticultural, Tendercrop, Tenderwhite, Tennessee Green Pod, Top Crop, Blue Lake, All Green, Burpee Improved Bush, Dixie Butterpea White, Fordhook 242, Henderson, Jackson Wonder.

Burpee Seed Company: Baby Fordhook.

Sutton & Sons: The Prince, Masterpiece, Selected Canadian Wonder, Phoenix Claudia.

Vaughan's Seed Company: Landreth Stringless Green Pod. 47 -

A ramdomized 31ock design with three replications was used. The plot size was 75 sa. ft.

The cultivars matured at different times and harvest was carried out over the period from 28th December 1970 to 11th January 1971. Since the cultivars are being tested for suitability to mechanical harvest, each plot was harvested only once.

Records were made of type, straightness, length, stringiness of pod, habit of plant, height at which pods are borne, uniformity of maturity and yield. Uniformity of maturity is of obvious importance if once over mechanical harvesting is to be carried out.

In general, the highest yielding cultivars were also found to be best as regards physical characteristics. The best green, round podded cultivar was Green Lakes 5A, the best green flat podded cultivar was The Prince and the best wax round podded cultivar was Earliwax.

The wax types will be omitted from future trials because of their poor market potential. The following 27 cultivars which yielded over the equivalent of 3,500 lbs./acre will be given further trial: Green Lakes 5A, Olympia, Top Crop, Corneli 14, Catskill RB4, The Prince, Provider, Contender, Bush Blue Lake 274, Avalanche, Slenderwhite, Extender, Cascade, Commodore Improved, Bountiful, Gallatin 50, Bush Romano 14, Processor, Mountaineer, Sutton's Selected Canadian Wonder, Tenderwhite, Tendercrop, Landreth Stringless Green Pod, Tenderette, Phoenix Claudia, Sutton's Masterpiece.

The cultivar Taylor Horticultural appears promising as a dry seed type and will be tried again.

Lettuce:

Three trials were carried out. The first was planted on 20th May 1970. This trial was direct seeded with a Stanhay Precision Planter but had to be abandoned because only very few of the seeds geminated. It is believed that this was due to dormancy in the lettuce seed induced by the high temperatures in the field. Good germination was achieved in subsequent sowings in seedboxes using the same batch of seed.

The cultivars used were:

Ferry Morse Seed Company: Great Lakes 54, Great Lakes 366, Great Lakes 6238, Green Bay 14731, Greenland.

Dessert Seed Company: Great Lakes 407, Great Lakes 659-G, Great Lakes 660, Great Lakes 101-G.

Niagara Seed Company: Golden State D, Great Lakes Standard, Great Lakes 65, Great Lakes 66, Great Lakes Shipper 212, Great Lakes Mesa 659, Great Lakes 659 MI, Great Lakes 6238, Vanguard MI, New York #12, Bellaverde. - 48 -

Keystone Seed Company: Bellaverde MC, Calmar MC, Climax MC, Climax 84 MC, Great Lakes R 200-95 MC, Great Lakes 118 MC, Great Lakes 659 MC, Iceberg, Minetto MC, Primaverde MC, Vanguard MC.

Standard Variety sold at Min. ot_ Agric. Seedstore: Mignonette Bronze.

In the second trial, the seed was sown in seedboxes on 10th June 1970, and the seedlings were transplanted on 3rd of July.

A randomized Block design with three replications was used. Plot size was 50 sq. ft. The trial was inspected on 19th August 1970.

A third trial was carried out in November 1970, using a similar experimental design and plot size to that used in the second trial. The cultivars were evaluated on 5th January 1971. In both trials the cultivars were evaluated on size and compactness of head, texture, taste and degree of bolting.

At present only Minetto and Mignonette Bronze can be recommended for commercial used. However, the following cultivars gave indications of heading and it is felt that better results may be obtained with these cultivars at higher elevations.

Greenbay 14731, Great Lakes 65, Great Lakes Mesa 659, Great Lakes 6238. Belleverde MC, Iceberg, Great Lakes 659 MI, Bellaverde, Great Lakes R 200-95 MC, Vanguard MC.

Red Beet:

Two trials were carried out, the first being planted on 12th and 13th May 1970 and the second on 23rd June 1970.

The cultivars used were:

Asgrow Seed Company: Asgrow Wonder, Redpack

Ferry Morse Seed Company: Detroit Dark Red, Morse's Strain, Fire- chief .

Burpee Seed Company: Improved Blood, Extra Early, Red Ball.

Vaughan's Seed Company: Winterkeeper.

Ohlsens Enke Seed Company: Crimson Globe, Cylindra 504, Osena, Cylindra 0176 Osena, 'Cylindra 0303 Osena, Improved Original, Fireball, Sigma Osena.

Northrup King Seed Company: Early Wonder Stays Green, King Red, Mono King Explorer, Royal Red, Special Crosby.

Sutton Sons: Early Bunch, Globe. - 49 -

Dessert Seed Company: Hybrid F1 Pacemaker.

Niagara Seed Company: Early Wonder Improved, Detroit Medium Top, Detroit Dark Red, Short Top, Early Wonder, Tall Top.

Keystone Seed Company: Detroit Dark Red, Detroit Dark Red, Medium Top, Detroit Dark Red, Canner Strain, Detroit #12, Detroit Perfected, Early Wonder, Ruby Queen.

A randomized block design with 3 replications was used. Plot size was 50 sq. ft. The first trial was evaluated and the second was harvested on 10th September 1970.

The cultivars were judged on shape, size, skin texture, size of top and tissue colour. The most promising cultivar selected from both trials was Hybrid F1 Pacemaker. This cultivar as well as the following 9 cultivars will be tested in semi-commercial sized plots in the near future: Redpack, Firechief, King Red, Ruby Queen, Royal Red, Detroit Dark Red, Detroit Perfected, Mono King Explorer, Special Crosby.

Radish:

This trial was planted on 2nd February 1971. The cultivars were grouped as follows: Red rooted cultivars, Red and White rooted cultivars, and White rooted cultivars.

The Red rooted cultivars were as follows:

Ferry Morse Seed Company: Cincinnati Market, Red Devil.

Ohlsens Enke Seed Company: Non Plus Ultra, Long Red, Round Red Winter, Saxa 455 Extra Short Top Osena, Wurzburgh.

Northrup King Seed Company: Firecracker, Stoplite.

Dessert Seed Company: Mexican Bartender, Red Boy, Rojo Grande.

Asgrow Seed Company: Globe Master.

Keystone Seed Company: Champion, Cherry Belle, Chinese Rose Winter, Comet, Red Prince, Scarlet Globe, Medium Top.

Burpee Seed Company: Burpee's Earliest Scarlet Button, Rapid Red, Red Giant, Scarlet Globe.

Vaughan's Seed Company: Cavalier.

The Red and White rooted cultivars were:

Ohlsens Enke Seed Company: Gaudry, Pernot, Rovi Osena Novelty, Scarlet Gem. - 50 -

Keystone Seed Company: French Breakfast, Long Brightest Scarlet, Sparkler.

The White rooted cultivars were:

Ohlsens Enke Seed Company: Sezanne

Northrup King Seed Company: Giant White Globe.

Keystone Seed Company: California Mammoth White, Icicle.

Burpee Seed Company: Burpee White, White Straasburg.

A randomized block design with three replications was used. Plot size was 50 sq. ft. The trial was harvested on 3rd March 1971.

The characters which were used to evaluate the cultivars were shape, size of root, colour and size of top. The best of the red and white rooted cultivars was Gaudry. Rovi Osena Novelty was promising and is very early maturing. Of the red rooted cultivars, Champion was found to be excellent. Other cultivars selected for re-trial are: Comet, Burpee's Earliest Scarlet Button, Red Devil, Non Plus Ultra, Wurzburgh, Round Red Winter, Burpee's Rapid Red, Stop Lite, Saxa 455 Extra Short Top Osena, Red Prince.

CONCLUSIONS

In all the crops examined, with the possible exception of onions and bpanri, cultivars which are better than those currently used have been found. To keep up to date with cultivar improvement, it will be necessary to examine new cultivars as they come on the market each year. This has to be done systematically as it was not generally found possible to select the best cultivars for Barbados merely by consulting catalogue descriptions. Ulti- mately it may be profitable to carry out more breeding work for certain crops within the Caribbean area, paying particular attention to such characteristics as high temperature tolerance, disease resistance and daylength requirement.

SUMMARY

During 1970-1971 a large number of cultivars of the following vegetables was screened: onions, carrots, cabbage, snap beans, beetroot and lettuce. The following cultivars were selected for further trial:

Onions: (selected from 54 cultivars) Granex F1 Hybrid (different strains), San Joaquin, Dessex, Early Top for June planting; Granex F1 Hybrid, Texas Early Grano (various strains), Early Top, San Joaquin, Dessex for October to January planting.

Carrots: (selected from 50 cultivars) Chantenay Red Core #5 (Keystone), Sutton's Favourite, Danvers Half Long Red Cored, (Northrup King), Sutton's Concord, Sutton's Early Gem, Hybrid F1 Gold (Dessert), Japanese Hybrids for June, July planting. - 51 -

Cabbage: (selected from 72 cultivars) Express Cross 50, Express Cross 60, Summer Stride, Summer Pride, C-0 Cross 69, C-M Cross 70, Stonehead Hybrid, Emerald Cross Hybrid (Burpee).

Snap Beans: (selected from 34 cultivars) 28 cultivars which yielded more than the equivalent of 3,000 lbs/acre will be re-tested.

Beetroot: (selected from 34 cultivars) Hybrid F1 Pacemaker, Redpack, Firechief, King Red, Ruby Queen, Royal Red, Detroit Dark Red, Detroit Perfected, Mono King Explorer, Special Crosby.

Lettuce: (selected from 32 cultivars) Minetto, which was the most promising although the heads were small. None of the Great Lakes selections gave hard heads when planted in either June or October. At a cooler site the following cultivars will be re-tested: Greenbay 1473, Great Lakes 65, Great Lakes Mesa 659, Great Lakes 6238, Bellaverde, Bellaverde MC, Great Lakes R 200-95 MC, Iceberg, Vanguard MC.

Radish: (selected from 37 cultivars) Champion and Red Prince most promising. 13 cultivars selected for re-trial. - 52 -

FUNGICIDE FIELD TRIAL AGAINST EGGFRUIT ANTHRACNOSIS

J. Fournetii/

In a former paper (FOURNET 1970), we studied the causal organism of Eggfruit anthracnosis, one of the most destructive diseases of this crop in the Caribbean. This parasite proved to belong to the Colletotrichum gloeosporioides group, but all our isolates were specialized, and attacked only Eggfruit, Pepper fruits and Solanum torvum berries, the latter probably being the natural source of inoculum.

The present paper deals with a fungicide trial which was carried out in the field from December 1970 to February 1971.

Experimental design

The variety was "Violette longue", grafted on Solanum torvum, to avoid too strong mortality by Southern bacterial wilt, the soil being highly infested by Pseudomonas solanacearum. In a latin square design (4 x 4 - 20 plants/plot) three chemicals were tested.

Benomyl (Benlate) 50% (100 g/hl) Mancozeb (Dithane M 45) 80% (300 g/hl) Propineb (Antracol) 70% (300 g/hl)

The whole being compared with a non-treated control.

The plants were placed in the field by the first day of October.

An equalizing Mancozeb spray (November 24) followed by an equalizing harvest (November 26) were done.

The inoculum (in vitro inoculated twig fragments of Solanum torvum) was placed above each plant (December 1). Fifteen treatments were done from December 8 until February 19 (73 days).

The mean frequency was about a treatment every 5 days; a weekly treatment proved insufficient on account of the very heavy rainfallas during December (510 mm).

Eight harvests were done during the notation period. On 10 plants per plot, chosen for their regularity, we noted:

The total weight harvested. The total number of fruits harvested.

\J INSTITUT NATIONAL DE LA RECHERCHE AGRONOMIQUE GRAAG - Domaine Duclos - Petit-Bourg - Guadeloupe. - 53 -

The commercial weight (healthy fruits). The number of salable fruits (healthy fruits). The mean number of spots per fruit (noted on the 3 first harvests).

RESULTS

The results are summarized in Table I, and their statistical significance (tested by the DUNCAN test) is showed in Table II. The considerable amount of primary inoculum and the heavy rainfalls of December may explain the low harvests.

TABLE I

Control Benomyl Mancozeb Propineb

Total weight (kg/plant) 0,659 0,937 1,083 1,667 harvested

Total number of fruits harvested per plant 7,75 9,27 10,20 13,77

Commercial weight (kg/plant) 0,085 0,179 0,431 0,969

Number of salable fruits per plant 0,80 1,65 3,47 7,60

Mean infection rate (spots/fruit) (3 first harvests) 16,75 12,26 3,03 1,31

Number of spots/plot (3 first harvests) 318,25 361,67 107,56 56,75

TABLE II

Control Benomyl Mancozeb Propineb

Total weight harvested c be b a

Total number of fruits harvested b b ab a

Commercial weight/plant c be b a

Number of salable fruits per plant c c b a - 54 -

The numbers of spots/plot were studied by covariance analysis, because the number of fruits harvested were different. Highly significant difer- ences were found.

The total number of fruits harvested varies according to the more or less important young fruits' abortion. These very severe attacks mainly occur in the control plots. Furthermore, it may be said from the results that the more effective the treatment is, the bigger the fruits can grow.

The results show that the best chemical we tested was undoubtedly Propineb (Antracol); Mancozeb has a weaker effect, and Benomyl has but a very poor action. Tfiie weak effectiveness of Benomyl may be explained by the fact that this systemic fungicide is not transported into non- perspirating organs, as was shown by PETERSON AND EDGINTON (1971). Egg- fruit is known to be such an organ; we can therefore trust only the super- ficial preventive action of Benomyl, which proved to be very poor in our trial.

Other diseases

We observed the other diseases which occasionally occurred in the plots. The main disorfers were leaf necrotic spots, twig brown spots and twig wilt. Isolation showed that leaf spots were caused mainly by Corynespora sp., twig spots and wilb by Phomopsis vexans Sacc. & Syd., sometimes associated with the same Corynespora. We noted the importance of these symptoms in each plot. The results are summarized in Table III and their statistical significance is shown in Table IV.

TABLE III

Control Mancozeb Propineb Benomyl

Twig spots/plant 7,05 1,32 0,92 0,45

Spots per leaf 23,95 4,22 3,92 0,92

TABLE IV

Control Mancozeb Propineb Benomyl

Twig spots/plant b a a a

Spots per leaf b a a a - 55 -

The three chemicals tested showed a very good effectiveness against leaf and twig spots; Benomyl seems to be better (which appears strikingly by a mere observation of the plots), but no significant differences could be shown between Mancozeb, Propineb and Benomyl. In this case, Benomyl probably exerts a systemic activity. On a few out-of-trial plants, we observed the same action of Benomyl by soil-drench.

LITERATURE CITED

1. Fournet J., 1970. First indications on a rot of Eggplant fruits (anthracnosis) caused by a Colletotrichum. VIII th Annual Meeting of CFCS, Santo Domingo, 1970.

2. Peterson-, Carol A. and Edginton, L. V. 1971. Transport of Benomyl into various plant organs. Phytopathology, 61(1):91-92. - 56 -

Influence of air temperature and humidity during the vegetative growth on some structural characteristics of the leaf of Capsicum annuum L.1/

P. G. SCHOOCH^

ABSTRACT

The growth of leaves is presented with an analysis of the epidermic cells divisions and expansion of the limb. The influence of the air temperature and humidity on the growth of the leaf is also exposed.

A particularly attention is accorded to the number of stomata of the growth-leaf as also the percentage of stomata in relation with the cells in different climatic conditions.

INTRODUCTION

The size of a leaf is determined both by the size and the number of its cells. According to plant species cell division and cell growth occur simultaneously or during two successive stages. For Lupinus albus and Helianthus annus, for tixample, cell division does not stop until the leaf has the half ot its maximal size (SUNDERLAND, 1960). On the contrary with several varieties of Lactuca sativa (BENSINK, 1958) shows with evidence a succession of two periods, a primordial stage during occur only cell divisions, and another stage of cell expansion. Stomatal initiation occurs just before the mitosis stop, by a dissymetrical cell division (BUNKING, 1956). Actually it seems likely that the respective length not only amongst plant species, but also amongst the leaves of the same plant.

The speed of cell divisions is strongly influenced by climatic conditions. It appears (BENSINK, 1958; DALE & MURRAY, 1968) that the number of cells in a leaf generally increases when conditions favourable to photosynthesis by the leaf are realized. The primordial stage is very important since the potential expansion of a leaf is determinated by the number of its cells.

Most of the results cited were obtained with epidermic cells. It is obvious that the evolution of different tissues in a leaf is not always

XJ The data presented in this paper were included in a thesis submitted to the University of Marseille-Luminy (France) for the "Doctorat de specia-lite".

2/ Present address: Institut National de la Recherche Agronomique, Station de Bioclimatologie, Centre de Recherches Agronomiques des Antilles et de la Guyane, Petit-Bourg, Guadeloupe (French West Indies). - 57 -

similar. In tobacco leaf primordia, for example, (AVERY, L933) the mid- rib is differentiated first. Cell divisions stops first in epiderm, then in mesophyll, and at last in the palisade tissue. On the contrary, epidermic cells are still elongating when mesophyll cells have stopped. Furthermore, cell divisions stop first at leaf tip, then in the other lobes.

Optimal climatic conditions for these transformations are not very well known, especially as these studies are often done without an exact knowledge of the level of water supply. WAGENMANN 91961) alone points that the leaf area increases with soil moisture, either by the number of cells, or by their size, or by both of them.

It appears therefore interesting to study the influence of different transpiration conditions (caused principally by differences in relative humidity of the air) on cell divisions and cell expansion in the leaves of pepper (Capsicum annuum) seedlings. We have also studied the influence of a constant temperature during day and night compared with alternated temperatures. This problem, is very important indeed for mid season greenhouse crops in Southern France, and for tropical areas under trade winds, when night temperatures are high during the rainy season. This circum- stance perhaps explains the low yields obtained with vegetable crops during this period.

MATERIALS AND METHODS

Growing substrate for the plants

Pepper seeds (C.V. YOLO WONDER) are germinated on wet blotting-paper during 4-5 days at 20"C, then placed in square seed pans (31 x 31 x 7 cm) filled with commercial enriched peat substrate (TKS2). The mineral'nutrition of the plants can be considered at the same in the various treatments. The plant-stand at the beginning is of 50 by seed-pan, i.e., approximately 520 plants m^. The systematic samplings during the experiments are done in a way as uniform as possible in order to decrease this density approxi- matively in the same way for each seed-pan. The plants are watered once a day in order to compensate evapotranspiration. Four experiments were realized in the following climatic conditions:

Climatic conditions

During the whole experimental period, the plants are kept in air conditioned rooms. Climatic conditions similar for the 4 treatments are summarized in table 1.

Artificial illumination during the day is obtained with fluorescent lamps (Power groove), the radiation of which is very strong in the spectral bed 550 - 700 nm, especially active for photosynthesis. A glass ceiling, between the lamps and the airconditioned room reduces considerably the transmission of infrared radiations. For this reason, although the liminous radiation above the plants is about 20,000 lux, energetic - 58 -

Table 1.—Climatic condition similar for the 4 treatments

Total radiation: air:temperature above the plants Conditions Length Luminous Energetic

Day 14 hours 20.000 lux 58 W. m-2 25,5'>C

Night 10 hours 0 0 Varies with the treatments.

_2 radiation is no more than 58 W.m . The distance between the lamps and the plants is progressively reduced as the lamps become older, but it is always more than 1,5m. The mass of air of the air conditioned room and of its regulating annexes (25 m^) passes approximately 200 times during one hour through a potent air flower, so that the linear speed of the air is about 1 m. sec--'- in the room. Air from outside is introduced, so that air in the room is changed about 3 times during one hour. Since carbon dioxide is consumed by photosynthesis at a rate of 16 mg. dnT^.h-*-, for a leaf area index equal to 1, the need for air renewal would be of one third/one hour. We can therefore consider that in the air conditioned room the carbca dioxide amount in the air remains constant and normal (0,03%).

In the different treatments, relative humidity and night temperature are not the same (Table 2) with the same of air renewal, and increase of relative humidity leads to a decrease of transpiration by the plants. A slight difference in leaf temperature is therefore measured with several thermocouples pricked in the secondary veins of the leaves. Measuring the water loss of some pots (evaporation by the soil is avoided by covering it with an aluminum foil), and the corresponding leaf areas (for one side of the leaf only) allows to compute leaf transpiration for periods of several days.

Table 2.—Differences in climatic conditions between the treatments

_ Night „ . Leaf tempera- Leaf trans- reft_ tempe- , e.j"vf5% ture during piration ments r humidity- » » rature _ the da y mg.cm_ 2^.m n -1

1 19.0 °C 40% 25.0 °C 0.13

2 19.0 °C 72% 25.3 °C 0.05

3 25.5 °C 40% 25.0 "C 0.13

4 25.5 "C 72% 25.3 "C 0.05 - 59 -

Measured realized

Sampling. Three leaves (3rd, 5th and 7th leaves following the coty- ledons) chosen for their uniform repartition along, the main stem are regularly taken from 20 plants. These three leaves are characteristic of the juvenile stage of the pepper plant. Samplings are done go from the apparition of the 3rd leaf, till the complete differentiation of the 7th leaf. Each figurative point on the graphs is the mean of 20 samples.

Leaf area. The limb of a very young leaf is folded on its mid-rib, the predominant part of such a leaf. It is therefore very difficult to estimate a leaf area reduced to this mid-rib. For leaves smaller than 3 cm2, it is possible to measure the leaf area with a graphic planimeter with an approximate of 0,1 cm . For leaves larger than 3 cm3 the leaf area can be measured more quickly.

RESULTS

Leaf growth

The general shape of the curves expressing the growth in leaf area (for the 3 leaves sampled, 3rd, 5th and 7th) in terms of time is in good agreement with generally accepted results, especially for plants growing alone, some leaves of which go on growing during the whole time of the experiments. The maximal growth-speed increases with the leaf-rank. As a consequence at the same physiologic age, (during the vegetative stage) a leaf of the rank n is larger than a leaf of the rank (n - 1).

The climatic conditions of treatment 1 and 3 differ from those of the treatments 2 and 4 only by the relative humidity of the air. The decrease of air saturation deficit reduces appreciably transpiration, and induces only a slight increase of leaf temperature. The difference in temperature cannot explain the differences observed for growth. Leaf area is greater under high humidity and this increase is yet greater when the rank of the leaf higher.

The effect of air saturation deficit is especially important when the night temperature is high (treatment 3 compared to 4). As a result the influence of air moisture on leaf development will be especially determinant in tropical areas, where air temperatures during the night remain high. On the 60th day after sowing, the increase in leaf area is very important (140%) and the plants are approximately five days earlier with strong relative humidity.

Climatic conditions in treatments 1 and 2, compared to 3 and 4 differ only by night temperature (19,0 or 25,5°C). Low night temperatures are clearly favorable to leaf growth, which is 100% superior in dry atmosphere, 25% in wet atmosphere. - 60 -

Table 3.—Leaf areas on the 60th day after sowing (cm2)

Total area Treatments 3rd leaf 5th leaf 7th leaf of the 3 leaves

1 (402,25/19) 55 90 95 240

2 (722,25/19) 95 120 150 365

3 (40%,25/25) 30 40 50 120.

4 (72%,25/25) 60 105 125 290

Growth in area of the epidermic cells of the leaf

The mean area of the cells does not reach a distinct maximal value during the life of a leaf in our experimental conditions. The mean area of the cells decreases with the leaf-rank. For the same treatment these curves cannot be inferred from each other by a translation of the time- scale (fig. 5).

In the same way that for macroscopic leaf growth, the growth in area of epidermic cells is accelerated under wet conditions (fig. 6, 7, 8). Low night temperatures favour cell expansion, especially in dry conditions.

Table 4.—Mean areas (in pm2) of epidermic cells on the 60th day after sowing (precision + 50 pm2)

Treatments 3rd leaf 5th leaf 7th leaf

1 (40%, 25/19) 3900 3300 2800

2 (72%, 25/19) 4600 4000 3500

3 (40%, 25/25) 9800 2300 2100

4 (72%, 25/25) 4200 3500 3100 - 61 -

Number of cells in the leaf epidermis

The number of cells in the epidermis of a leaf (in Pepper plants during the juvenile stage) increases with leaf rank (table 5). In constant climatic experimental conditions the area of leaves of an higher rank is always greater since the cells are more numerous, although they are smaller. With an approximation of + 2 days for the length of the primordial stage we can state that it does not change with air relative humidity or with night temperature. On the contrary, the cell division intensity is accelerated in wet conditions. High night temperature increases also leaf earliness: the end of cell division occurs 3 days earlier in dry conditions, 8 days earlier in wet conditions. Low night temperature (or large differences in temperatures between night and day) favor cell divisions intensity, especially in dry conditions. This increase is more important in high-rank leaves.

Table 5.—Mean number of cells in the upper epidermis of a pepper leaf (millions of ceils)

Treatments 3rd leaf 5th leaf 7th leaf

1 (40%, 25/19) 1,5 3,3 4,2

2 (72%, 25/19) 1,6 3,5 5,2

3 (40%, 25/25) 1,4 2,1 2,5

4 N C M 25/25) 1,6 3,0 3,3

Variations in stomatal density

Owing to cell growth, stomatal density for 1 mm^ of leaf is not constant, it increases very quickly at the end of cell division, then decreases to a limiting value which could be reached if the cell decreases to a limiting value which could be reached if the cell expansion would stop. On the contrary, the percentage of stomata to the total number of cells, in given climatip conditions, does not vary any more with time after stomatal differentiation.

The percentage of stomata to the total number of cells is therefore increased of more than 60% in wet atmosphere, with low night temperatures (comparison of 1 and 2) of more than 20% with high night temperatures (3 and 4). Stomatal differentiation seem to be less influenced by a - 62 -

Table 6.—Percentage of stomata to the total number of cells (upper epidermis pf the leaf; with an approximation of + 0,5%)

Treatments 3rd leaf 5th leaf 7th leaf Mean

1 (40%, 25/19) 7,1% 5,6% 6,5% 6,4%

2 (72%, 25/19) 11,0% 10,6% 9,4% 10,3%

3 (40%, 25/25) 6,3 % 6,8% 7,7% 6,9%

4 (72%, 25/25) 6,6% 9,5% 9,1% 8,4%

variation of night temperature. However, in wet conditions•the percentage of stomata is slightly higher under low night temperatures.

Owing to the difference in leaf growth in the two conditions, the stomatal density for 1 mm2 reaches more rapidly its limiting value under high night temperatures (fig. 9 and 10).

DISCUSSION

Leaf growth dynamics

In the experimental conditions of our air-conditioned rooms, the experiments did not last a time long enough to reach a complete stop of leaf growth. Other observations allow us to think that a stop in leaf growth in natural conditions for a plant population is amongst other causes a consequence of a shortage of light. On the contrary in our experiments the plants could be considered as alone. Further more the leaves are radially disposed without overlapping (In trials realized now in Guadeloupe the experiments are kept a longer time to reach a final stop in growth).

The growth of a pepper leaf proceeds therefore in two distinct successive steps: the primordial stage during which cell divisions occur and the cell expansion stage, the expansion potential of a leaf being strongly linked with rate of cell division during the first stage.

It will be interesting to verify if the systematic decrease of cell area is always linked with leaf-rank, and that in any instance these curves will not be deductible from each other by a translation of the time-scale. - 63 -

It ia generally accepted that each plant species has a characteristic stomatal density. It is true in given climatic conditions, when the leaf has reached its mature stage, when cell expansion stops. We have demonstrated again that this density varies with leaf-age, a maximal density being reached when the cell divisions stop.

Influence of air moisture on the structural characteristics of a leaf

Although numerous authors (SUNDERLAND, 1960; DALE, 1964; MILTHORDE, 1959; NEWTON, 1963; MILTHORPE (. NEWTON, 1963) have studied the growth of leaves under various environmental conditions one of them was concerned with sweet peppers, nor with influenced of the relative humidity of the air. From our studies it appears that pepper is very susceptible to water and transpiration conditions, since in spite of the supply low transpiration rates reached in our experiments, we can observe that a variation in relative humidity from 40% to 72% has a strong influence on global growth and stomatal differentiation. The stomatal density varies during leaf differentiation, but also with climatic conditions.

Influence of night temperature on the structural characteristics of a^ leaf

The night temperature effects are numerous. We know that respiration during the night decreases with temperature. If night temperature is kept the same as day temperature, consequently plant respiration increases, and of course losses in dry matter. Furthermore, for the same photosynthetic rate, the leaf, root ratio can be different. A compensation phenomenon can also occur between leaf thickness and leaf area.

As stated above, leaf area depends also on night temperature which, when high, restrains leaf expansion. Finally we have noted general times and interaction between moisture and night temperature effects on leaf development. Probably a similar interaction occurs with other climatic factors.

ACKNOWLEDGEMENT

Our thanks are due to Mr. G. THOUY for technical assistance. - 64 -

A Coraparat ive Trial of Cucumber Varieties and Hybrids in Guadeloupe

F. Kaaan et G. Anais^

In the French West Indies, cucumber is eaten boiled or in salad. We are presently interested only in this latter use. Production of salad cucumber is developing rather rapidly.

IRAT Agency in Martinique showed that varieties adapted to southern United States conditions were often satisfactory in the French West Indies. Therefore, variety Ashley was recommended for some years.

However, varietal choice was recently rapidly modified, new cultivars with original characters of disease resistance or sexual type were introduced.

We intend to study some of these new introductions with emphasis on disease reaction and fruit quality.

This trial was realized in our main station, Domaine Duclos, on a ferralitic soil. It followed a sweet potato crop on a limed soil.

Organic manure (60 metric onts/ha) was added, as well as mineral ferti-

lizer (150 kg N/ha, 60 kg P20g/ha, 120 kg K^O/ha). Nitrogen applications were fractionated.

The trial was directly field sowed Dec. 2, 1970 and harvested for the last time February 11, 1971. Plants were trellised and pruned; density 17,000/ha.

Meteorological data

Temperature °C Daily Daily Av. Mag. Av; Mm.

December 510 mm 26,9 20,7

January 185 mm 26,7 19,2

Some irrigation was given since middle of January. No phytosanitary treatment was made before the end of January in order to observe the development of diseases. However, we made a treatment of the seedlings against Pythium by using chloroneb.

1/ Station d'Amelioration des Plantes. Centre de Recherches Agronomiques des Antilles et de la Guyane, I.N.R.A. (France), PETIT-BOURG (Guadeloupe). The technical aid of J. Manyri, G. Gelabalt, and C. Vincent is greatly appreciated by the authors. - 65 -

RESULTS

I. Sexual type

All pure line varieties tried are monoecious but 6 hybrids manifest some gynoecy with variable degrees of intensity: F^ Ashley, F, Cherokee, F^ Cherokee 7, F^ Gemini, F^ Gemini 7, F^ Z^A. Fj^ Ashley was heterogeneous for gynoecy. Some samples of gynoecious commercial hybrids were mixed by the breeders with small proportions of seed of monoecious varieties which were sometimes differently colored.

II. Disease resistance (See table 1)

We had first downy mildew (Pseudoperonospora cubensis) then powdery mildew (Erysiphe cichoraceanum) and Gummy stem blight (Mycosphaerella citrulina) on leaves.

We noted the abundance of spores of the mildews on older leaves (Jan. 25th) no spores observed on 0 noted plants. Plants noted 1-2 were considered tolerant, the other susceptible.

Conversely, we noted the proportion of leaves manifesting some necrosis to the total of expanded leaves.

We note that Cvs resistant to the 2 mildews (F^ Cherokee, F^ Cherokee 7, Poinsett) manifest abundant necrosis on leaves.

On the contrary, some tolerant Cvs: F-^ Gemini, F^ Gemini 7, Hawaii 70 C 78 had a more persistent vegegation.

III. Yield (See table 2)

Fruits were harvested from January 18th till February 11th. They were picked at time of easy spine removing.

The end of the crop was characterized by intense defoliation, possibly due to diseases and excessive pruning.

Yields were low with a maximum of 2 kg/plant (34 metric tons/ha).

IV. Fruit characters

Weight (table 3)

Color (table 3). Only F, Cherokee, F^ Cherokee 7, F^ Gemini, F^ Gemini 7 and Poinsett were well colored (Note 5). Note 0 corresponds to yellowish fruits.

Length to diameter ratio (table 4). This is important for a possible export market to Europe where consumers presently prefer large and elongated fruits with tapered ends and dark green color. American Cvs are unadapted for this market. On the contrary europena Cvs as Vert Long Maraicher, Vert long de Chine, Rollisons Telegraph and F^ Z^A produce elongated fruits with tapered ends, unhappily very often distorded, with irregular fecundation. - 66 -

CONCLUSION

Some of Che best yielding selections cannot be recommended for various reasons.

Hawaii 70 C 78, an experimental breeding line, is heterogeneous for powdery mildew tolerance and fruit characters (shape, color, size).

F^ Z^A, an experimental hybrid between an american selection and a gynoecious european line, is susceptible to the mildews and bears many distorted fruits.

F]_ Ashley is heterogeneous for sexual type.

Therefore, the best commercial CVS in this trial appear to be F^ Gemini 7, F^ Saticoy, F-^ Lehua 1, Fj, Gemini. - 67. -

Table 1.—Tolerance to diseases

Notation: 25-1

Cvs Downy mildew Powdery mildew Necrosis

F-^ Admirable 7 T S 0,15

Ashley S S 0,14

F^ Challenger T T 0,21

F^ Cherokee R .R 0,14

Fj^ Cherokee 7 R R 0,19

F^ Gemini T T 0,05

F^ Gemini 7 T T 0,07

Hawaii 70 C 78 T H 0,06

F]_ Lehua 1 T T 0,14

Marketer S S 0,19

Marketmore S S 0,20

F^ Palomar T T 0,14

Poinsett R R 0,20

PR 39 H S 0,20

Rollisons Telegraph S T 0,26

F-^ Saticoy T T 0,14

F^ Triumph T T 0,21

Vert long de Chine S S 0,29

Vert long Maraicher S S 0,15

FL Z4A S S 0,18

T: Tolerant S: Susceptible H: Heterogeneous - 68 -

Table 2.—Yield

Cvs Kg/pl Duncan test 5%

Hawaii 70 C 78 1,95 a

F-^ Gemini 7 1,60 a b

F1 V 1,50 a b c d

F-^ Saticoy 1,35 a b c d

Fj^ Lehua 1 1,35 a b c d

Fj^ Ashley 1,35 a b c d

F^ Gemini 1,30 a b c d e

F^ Triumph 1,15 b c d e f

F^ Cherokee 7 1,10 b c d e f

Fjl Challenger 1,05 b c d e f

F^ Palomar 1,00 b c d e f

Marketer 0,90 c d e f

F-^ Admirable 7 0,85 c d e f

Fj^ Cherokee 0,85 c d e f

Poinsett 0,75 d e f e

Vert long Maraicher 0,75

Legeneraux 0,75 *

Tablegreen 0,75 *

Marketmore 0,65 e f g

PR 39 0,65 e f g

Long .Marketer 0,60 *

Vert long de Chine 0,50 f g

Vert tres long de Chine 0,50 *

Rollisons Telegraph 0,20 g

Cvs sharing the same letter are not significantly different (Duncan test 5%) * no statistical data available - 69 -

Table 3.—Weight/fruit and coloration

Weight/fruit Duncan test Cvs Coloration (grams) 5%

Hawaii 70 C 78 380 a 1

F^ Gemini 7 320 a b 5

Fx Z4A 320 a b 4

F;l Lehua 1 310 b c 3

Vert long Maraicher 310 b c 0

F^ Admirable 7 300 bed 3

F^ Gemini 300 bed 5

Fj^ Palomar 300 bed 2

F^ Saticoy 300 bed 4

Vert long de Chine 290 bed 1

Vert tres long de Chine 280 * -

F-^ Triumph 270 bed 4

Rollisons Telegraph 270 * -

Fj^ Ashley 260 bed 2

Fj^ Challenger 260 bed 4

Fj Cherokee 7 260 bed 5

Marketer 250 bed -

Legenereux 250 * 4

Tablegreen 65 250 * -

Long Marketer 240 * 4

Fj Cherokee 230 c d 5

Market more 230 c d 4

Poinsett 220 d 5

PR 39 140 e 2

Cvs sharing the same letter are not significantly different (Duncan test 5%) * no statistical data available - 70 -

Table 4.—Length/diameter ratio

Length/diameter _ „ _ ,„ Cvs . Duncan test 5%

Vert long de chine 4,9 a

F1 Z4A 4,5 a b

Hawaii 70 C 78 4,3 b c

Vert long maraicher 4,3 *

Long Marketer 3,9 c d

Fj^ Ashley 3,8 c d e

Vert tres long de Chine 3,8 *

Challenger 3,7 c d e

F^ Gemini 3,7 c d e

Marketmore 3,7 c d e

Fj_ Palomar 3,7 c d e

Triumph 3,7 c d e

F^ Admirable 7 3,6 d e

F-^ Lehua 1 3,6 d e

Legenereux 3,6 *

Poinsett 3,6 d e

F-^ Gemini 7 3,5 d e

F^ Saticoy 3,5 d e

F^ Cherokee 7 3,4 d e

F^ tablegreen 65 3,3 *

Marketer 3,2 e f

F-^ Cherokee 3,1 *

PR 39 2,7 f

Cvs sharing the same letter are not significantly different (Duncan test 5%) * no statistical data available - 71 -

THE CHOICE OF A CITRUS ROOTSTOCK, RESISTANT TO

TRISTEZA FOR GUYANA

C.S. BAICHOO!/

The Ministry of Agriculture recognizes the desirability of expanding the citrus industry, and plans to establish citrus plantations in areas such as

Matthew's Ridge, the North Wast District, the Tumatumari area and other cooperative land development schemes.

Apart from fresh fruits and juices, a variety of citrus marmalades and preserves can also be produced. The refuse, comprising of peel, pulp and seeds, can be ground with a small amount of lime and dried to produce stock- feed. This feed is an excellent carbohydrate conditioning food for beef and dairy cattle. Citrus molasses and press liquor resulting from the manufacture of stock feed is used in the manufacture of mixed stockfeeds and alcohol.

Citrus peel oils are highly prized for their flavouring qualities. Ethyl alcohol is produced from waste citrus juices, and table wines are made from citrus j uices (2). Thus it is evident that a good citrus industry can lead to the development of auxiliary industries.

Although oranges and grape fruits have been produced in several areas for many years there are a number of citrus diseases recorded in Guyana.

1. Foot rot caused by Phytophthora gummosis is one of the main

diseases and in older trees it is followed by heart rot. The situation

is worsened by termite, condition of high humidity and excessive growth

of weeds.

2. In 1962 vein clearing and stem pitting symptoms of tristeza

were observed on West Indian Lime C. aurantifolia. In 1968 S. Bisessar

—' Central Horticultural Station, Guyana. - 72 -

found that West Indian Lime (C. aurantifolial and sweet orange sinensis,

growing on sour orange rootstock were infected with a mild strain of

TRISTEZA.

In 1970 the presence of tristeza on citrus was confirmed at Ho. 63 Sub

Station-Corentyne, Mara-Berbice River area, the Pomeroon, area and

Hosororo-North West District. The citrus raphid, Toxoptera citricidus a

potent vector of TRISTEZA. is recorded in Guyana since 1956. Until 1968

about 90 percent of the citrus rootstock used was sour orange C^ aurantium

which is well known to be susceptible to Tristeza. (1).

3. Recent tests indicate that among the other viruses, at least

Xyloporosis is present.

Rootstocks exert a significant influence on the growth and production of citrus trees. The choice of a rootstock could be the most important single factor responsible for the success or failure of the citrus industry. During the early thirties a root disease attacked the lime groves of the West Indies and killed lime trees on their own roots. With the use of appropriate citrus rootstocks the lime industry has been rehabilitated. Similarly, the citrus industry of Brazil and Argentina was almost destroyed by a virus disease-

Tristeza. Here again with the use of Tristeza tolerant rootstocks, the citrus industries in these two countries have been rehabilitated and expanded beyond that of the pre-TRISTEZA period. (6).

In view of the fact that:

(.1) Tristeza is present in Guyana.

(II) Tristeza has wiped out citrus industries in other countries.

(Ill) We are using Tristeza susceptible rootstock.

(XV) Rootstocks resistant to Tristeza are available. It is felt that possibilities of replacement of the Tristeza suscep-

tible rootstock with a resistant rootstock should be explored.

Studies on the performance of different citrus rootstocks were carried

out in Trinidad By I. Hosein and his data ara presented in Table I.

TABLE I

Toler- Resis- Length Toler- ance tance to to ance to foot- Suit- period of to Exo- rot or able commer- Root tris- cor- Gum- Fruit Vi- soil cial stock teza tis mosis Quality gour type quality Yield

Sour No Yes Good Excellent Good Clayey Long Good Orange to loam

Rough Yes Yes Poor Poor Excel- Sandy Short Very Lemon lent Good

Cleo- Yes Yes Good Excellent Fair Clayey Long Good patra to Manda- Sandy rin

Troyer Yes No Good Excellent Good Clayey Long Good Cit" to range loam

Rang- Yes No Good Fair Excel- Clayey Average Very pur lent to Good Lime loam

Sweet Yes Yes Poor Good Fair Sandy Long Good Orange to Loam

The perfomance of different rootstocks in Trinidad suggests that -

1. Rangpur lime could be used as a rootstock where the soil is heavy.

This rootstock is resistant to tristeza but is susceptible to Exocortis. This

exocortis can however, be easily controlled by using disease free budwood, -T4 - which is possible to ohtain form trees that are tested. It is a very vigorous rottstock and produces fruits of acceptable quality. It is resistant to Phytopthora gummosis in the same order as sour orange. Thus it is felt that it can easily replace the sour orange on heavy clay soils.

2. Three different rootstocks, iie*,. Rough lemon C. jambhiri, Cleopatra mandarin, C. reticulata and Sweet orange CL sinensis are poor in relation to

Phytopthora gummosis. At any rate gunmosis is not too much of a problem ort the sandy soils and this disease can ba controlled if the plants are treated as soon as they show signs of gummosis. Rough lemon C. jambhiri is most vigorous, it produces high yield, but quality of fruit3 produced is poor.

Production of Cleopatra mandarin C. reticulata on sandy soil is Ion and it is also slow growing.

Sweet orange C. sinensis produces good quality fruits. Some moia detailed studies on the suitability of sweet orange and rough lemon as a citrus rootstock needs to be carried out. A programme should be set up to test these various rootstocks in different areas in the country. The possible areas migh be Ebini, Central Horticultural Station, Matthew's Ridge and Wauna.

Program for testing budwood in Guyana -

Parent trees should be selected on the basis of-

(1) General performance

(2) Fruit quality and size

(3) Vigour of tree

(4) Resistance to virus diseases

(5) Resistance to Phytophtera gummosis

These parent trees will be identified and numbered so that proper records will be maintained. Each selected parent tree will be tested for the various - 75 - strains of virus diseases.. The motive will be to have virus free budwood locally so that exocortis will not be a problem. All propagation nurseries will have to ensure that relatively clean budwood is used in all propagation work.

The viruses that would be tested for, are Tristeza, psorosis, Exocortis and Xyloporosis. Different test plants will be used for each virus. The various parts of the plant will be examined for virus symptoms.

Table II will explain this procedure. TABLE II

Virue Teat Plane Operations after bud has taken Parts for examination SyapCODS of Disease Other Hotes

1* TciiCeta Line Seedings Lima seedlings cut back to leave 1. New flushes of the 1. Vein clearing I. Observations to be made on three leaves above the bud insert lime seedling 2. Stunting or seedlings every 3 days for 6 yellowing months 2. Ail other leaves and buda 2. After 6 months, 3. Stem pitting from cut back a tens of the lime exposed steal after seedling with bark 6 months removed

2. Psorosis Sweet orange 1. Sweet orsnge seedlings 1. Nev flushes of 1. Inter vein 1. Observations to be made on Seedlings allowed to grov the sweet orange clearing of nev seedlinga every 3 months for seedlings flushes 3 years

2. Stana of the 2. Characteristic 2. Plants can then be trans- stem orange seedlings scsling of bark ferred for further observa- on stems tions to permanent orchard

3. Xylo- Orlando 1. Orlando Tangelo seedlings 1. The wood of the 1. Gunning in the 1. Observations to be first psorosis Tangelo stock cut back and the bud section just scross bark made after 18 months and then Seedlings allowed to develop the bud unicn pre- after every 6 months for 3 pared by tho removal 2. Discoloured pits years of a piece of the and pegs in the wood bark

4. Kxocortis Rangpur 1. Rangpur line seedlings cut 1» Rangpur lime 1. Yellow stem 1. Observations•to be made Lins bsck to leave four buds stems blotches every 3 months for a year Seedlings above the bud insert 2. Cracking or 2. The bud can then be 2. All other leaves, brsnches lesions of the allowed to develop fully aud and buds removed except the sten the whole plant tranaferreJ bud being tested for further observations to a permanent orchard. - 77 -

The buds taken from selected parent trees will be inserted into the indi-

cators. Huds will be in turn taken from these indicators and budded on

to selected parent trees subsequently. Detection of a simple virus in

a tree, parent or indicator eliminates it from the indexing programme.

This will ensure that budwoods used for future propagation are free of

the virus diseases.

SUMMARY

According to reports and the finding of the Plant Plathologist

there is proof to Believe that there exists some strain of virus disease

in the country. The fact that sour orange as a rootstock has been exclu-

sively used for the past years is a clear indication that the citrus

industry is at stake, if ever the severe strain of Tristeza disease is

to strike Guyana. It is better to start now and set up a programme so

that a suitable rootstock can be used in Guyana to combat the Tristeza disease. A screening and indexing programme is necessary. The test plants to be used are sweet orange (C. sinensis) for Psorosis Virus,

Orlando tangelo for Xyloporosis, Rangpur lime for Exocortis and West

Indian lime (C. aurantifolia) for tristeza.

Rangpur lime a3 a rootstock should be used on the heavier soils, and rough lemon for lighter soils. Rangpur lime is susceptible to exocortis and this is only transmitted by infected budwood, therefore, all budwood must be virus free before it can be used. - 78 -

LITERATURE CITED

1. Bisessar, S. 1965. Review of work in Plant Pathology, Pans. 11: 394

2. Conner, D. Florida, Department of Agriculture, Bulletin No. 177, R. June, 1969.

3. Childs, J.F.L. and L.C. Knorr. 1965. Control of viru3 disease of citrus trees. Phytopathology, 55.677.

4. Fawcett, H.S. and Wallace, J.M. 1946. Evidence of the virus nature of citrus quick decline. Cal. Citrog. 32.50, 88-89.

5. Grant, T.S. 1961. Report on citrus disease in relation to plants for development of citrus plantings in British Guiana. Submitted to the Agricultural Ministry, British Guiana, 26th September, 1966. (Unpublished).

6. Hosein, I. Citrus rootstocks in the Caribbean citrus research, University of the West Indies, St. Augustine, Trinidad. Bulletin No. 15., July, 1969. - 79 -

SOIL RESOURCES OF GUYANA

by J. G. Steele,^ and H.N. Ramdln-/

INTRODUCTION

Guyana is located in the northern coast of South America between 1°10' and

8°32' north latitude, and between 56°31' and 61°20' degrees west longitude and has an area of about 83,000 square miles. Major physiographic divisions are the

coastal plain, the interior alluvial plains, the gently sloping sandy plateaus and plains, the Hilly or rolling uplands of crystalline rocks, and the mountains and high plateaus.

The nearly level coastal plain makes up about 9 percent of the country, and

the nearly level interior flood plains about 8 percent. Sandy or gravelly, gen-

tly sloping plateaus and plains make up about 25 percent; hilly or rolling areas with loamy soils, some of them rocky, 34 percent; and mountains or high rocky

plateaus, 17 percent. Not accounted for in this list is about 7 percent of the country, the parts not yet covered by aerial photographs when these calculations were made.

Average annual rainfall near the coast ranges from 74 to 115 inches (6). In much of the interior the annual average is within these same limits, but is reported to be only 55 inches at Orinduik on the Brazil border south of the

Pakaraima Mountains, and more than 150 inches at Mahdia on the northeastern edge of the mountains. In most part of the country there are two rainy seasons, May

through July, and November through January; and dry seasons in the other months.

In the southwest, however, 60 to 80 percent of the annual rain falls in one rainy

ki F.A.O. Technical Officer, Soil Surveys (1965-1966)

2/ — Soil Scientist, Ministry of Agriculture, Guyana. - 80 -

season from May through August; and at Mahdia there is no true dry season. The average annual temperature is near 80 degrees Farenheit. Actual temperature at

Georgetown 1889-1955, ranged from an extreme low of 72 degrees to an extreme high of not quite 90 degrees.

Types of vegetation cover a wide range. Several types of herbaceous marshes and of swamp forests occupy the coastal plain and the Interior lowlands. Part of the coastal plain in cultivated and part was formerly cultivated. Tropical rain forest covers much of the hilly and rolling areas. Evergreen seasonal forest, dry evergreen forest, and xeromorphic scrub vegetation cover much of the sandy gravelly, gently sloping plateaus and plains. Montane forest, seasonal forest and dry evergreen forest are In many of the mountain areas (9).

Tropical savannahs occupy parts of the gently sloping sandy soils In the northeast near the Berbice River, parts of the Interior lowlands and of the gently sloping sandy or gravelly soils of the southwest, and the southwestern edge of the Pakaraima Mountains. The types of vegetation were described in detail by

Fanshawe (9), and much more briefly by Braun, Derting and Suggett (3).

The general map of soil associations was abstracted and generalised from the reconnaissance soil survey maps made In 1961-64 and especially from tie one by

Braun, Derting and Suggett (3). The approximate area of each soil association shown on the map is given in table 1. More detailed data on the acreage of 10 groups of soils in the two parts of the coastal plain are In tables 2 and 3.

Table 2 was derived from semi-detailed soil surveys of about three fifths of the area covered, and from the reconnaissance soil survey of the remainder. Table 3 was derived from the reconnaissance soil survey. In these two tables the soils have been grouped into Land Capability Classes and Sub-classes.

Physical and chemical data for 10 extensive soils, representing 7 of the general soil associations are given in table 4. Six of these associations - 81 -

contain most of the land likely to be significant in agriculture for some time,

except the southwestern savannahs. Those savannahs, which are in associations

5, 8, and 12, are already used for extensive grazing and have further potential

for production of livestock.

COASTAL PLAIN

The coastal plain and adjacent alluvial areas, shown as associations 1, 2,

3, and 4 on the map, make up 4,613,000 acres or 7,200 square miles, about 8.7

percent of the country. Nearly all the people of the country live in the east-

ern part of this coastal strip, most of them between the Essequibo and the

Corentyne rivers, and nearly all farming is done there. Sugar is grown on

120,000 to 126,000 acres, nearly all in large, well managed estates. Rice is

grown on about 279,000 acres, mostly in farms of 10 to 15 acres, although a few

farms are larger. Approximately 400,000 acres more of the coastal plain are used for pasture.

Association 1, wet clay soils, contains the soils near the coast that consist

of marine sediments and are commonly called "frontland". They are nearly level,

and except on the sandy or loamy ridges they are naturally wet and must be drained before they can be cultivated. Most of the soils are in capability class I,

subject to few limitations.

Native vegetation in most places was water-tolerant forest; in some places

it was herbaceous or grass- like marsh plants. The soils mapped were classified

in 19 soil series. Most of them are Aquic Haplorthents in the new classification, or Low Humic Gley soils in the classification of 1938. Analytical data for

Corentyne clay, a soft, gleyed, somewhat salina soil, are given in table 4. The

two deepest horizons of this soil listed in table 4 contained 1400 and 1500 parts per million, respectively, of soluble salts. - 82 -

Most of the soils in Association 1 make good farm laud if they can be drained and protected from floods. The cost of drainage and of sea defense is high everywhere, and has been described as prohibitive in some places where the strip of good soil to be protected is narrow. Sugar cane and rice are commonly irrigated. Yields of rice could be improved on many farms by good management practices which include water control and use of fertilizer.

About 173,000 acres, mostly on margins of the peat swamps, contain toxic sulphides that are oxidized to acid sulphates if the land is drained. The limitations of these toxic soils need to be considered in any plan for development.

Association 2 consists of wet or moderately we silty soils or clay soils in the coastal plain and adjacent alluvial plains along the rivers. These have been called "riverain" soils. They lie in large areas back of the marine frontlands between the Berbice and the Corentyne Rivers, and also on natural levees aLong the lower courses of the large rivers. They are nearly level; they lie slightly higher than the "frontlands", and can be drained more easily. They are dominantly in capability subclass. If, fairly easy to drain and cultivate but low in fertility. The soils mapped were classified in 17 series. The most extensive soils are Typic Ochraquults; they are mostly Low Humic Gley and some

Humic Gley Soils.

Soils of Association 2 occur on natural levees along the rivers and were used for many of the early plantations. Nearly all of those plantations were later abandoned, probably in part because the systems of fanning did not maintain soil fertility. Although chemical properties of the soils are somewhat variable, most of the soils have lower base-exchange capacity and a much lower content of extractable bases than the wet clay soils of Association 1. Analy- tical data for one profile of De Velde silt loam are given in table 4. With proper drainage, fertilizer, and good management the soils can be made productive for a wide variety of crops. - 83 -

Association 3 consists of peat or much soils in swamps and marshes. The

areas of organic soils lie aback of the frontland clays. They are low and dif-

ficult to drain; and are in capability subclass Illm, severely limited for farm-

ing. Native vegetation is mostly swamp forest, but in some places is fresh-water marsh. The peat is locally called "pegasse". Drained peat or muck soils, as a

rule, have a low content of plant nutrients; a few contain soluble salts. In many places toxic sulphates, aluminium, or both, are present in the peat or muck

or in the underlying clay3. Fire often lowers the land surface, and leaves toxic

amounts of aluminium. Many crops can be grown if the management is intensive

enough although some require large amounts of lime and fertilizer. Flood-fallowing with salt water helps make some of the toxic soils suitable for crops. Because

of their limitations and the difficulties of management, the peat and muck soils have low capability for large-scale developments of farm land. Some successful

farms have been established. Many of the peat swamps are needed and are already

used for water conservancies, to provide water for irrigation and for domestic

and industrial uses.

Association 4, dominated by gently sloping silty soils, is a transition

between the coastal plain and the gently sloping sandy plateau and plains. The

association lies in several separate areas along the inner margin of the coastal

plain in the northeastern section. Slopes, as a rule, range from nearly level to

2 or 3 percent, but in some places are as much as 5 percent. The dominant capa-

bility subclass Is Hf, moderately limited by low fertility. Soil materials are

dominantly silty water-laid terraces of the Coropina geological formation, which

is described as of late Pleistocene age. Native vegetation is partly savannah of

coarse grasses and some shrubs, and partly evergreen tropical forest. The soils were classified in II series. The most extensive soils, which are slightly or

gently sloping, are Oxic Ochraquults and Ochric Plinthaquults. In terms of - 84 - great soil groups, they are Ground-Water Laterites and Low Humic Gley soils, and intergrades between these and other great groups. The moderately well drained soils are Plinithic Normudults; and are also classified as Red-Yellcrw-

Podzolic soils, some grading toward Ground-Water Laterites. The savannahs in this section are used for grazing; very little of the forest has been cleared.

Crops probably can be grown if they are fertilized heavily and managed well; the nearly level soils will need surface drains to remove water, and some of them might even then be too wet in the rainy seasons.

Table 4 shows that a representative soil, one that is somewhat poorly or poorly drained, has a high content of silt and low content of extractable bases, nitrogen, and phosphorus.

Areas of Association 4 shown on the map include some places, between and around the peat swamps, in which the silty soils occur as low silty islands surrounded by wet clays, some of which contain toxic sulphates. The acreage of these silty soils actually available for farming is therefore somewhat less than the amount shown in table 2.

INTERIOR FLOOD PLAINS AND LOW LANDS

Association 5 consists of the soils on interior flood plains and other lowlands. The largest areas form a nearly continuous belt that includes part of the savannahs north of the Kanuku Mountains, lies on both sides of the Lower

Rupununi River, and extends from the mouth of the Rupununi in a broad plain southeastward to the Corentyne River. Smaller areas are long the Burro-Burro

River, along the upper parts of several large rivers, and in basins of the

Pakaraima Plateau. Most of these soils are subject to flooding, some for three months or more each year, capability class III, severely limited for crops.

These soils are nearly level of gently sloping. Vegetation is partly savannah - 85 - and partly luxuriant rain forest. Extensive soils are Aquic Haplorthents

(Alluvial soils). Ochric Pllnthaquults (Ground Water Laterite soils), and some

Typic Thermoquods (Ground Water Podzols). Soils of other great groups are present.

The savannahs furnish grazing for several months each year after the floods- subside. Some farming might be done in places that are above the level of flood waters, but soil fertility is low. Some of the soils are extremely sandy or gravelly, and they are not suitable for any cultivation.

GENTLY SLOPING SANDY PLATEAUS AND PLAINS

Two associations in this group are dominated by sandy soils. The third association has in It a variety of soils that contain ironstone gravel or boulders.

Association 6 consists of deep, white sand. Geologically it corresponds to the Berbice Formation. Large areas lie just south of the coastal plain the northeastern section of the country, and scattered areas are elsewhere. Slopes are mostly gentle, but some on the sides of valleys are steeper than 15 percent.

Vegetation is mostly dry evergreen forest or the xeromophic shrub type. Analy- sis of a representative soil showed 97 or 98 percent white quartz sand and no clay to a depth of 34 inches, and no extractable calcium, magnesium, or potassium.

These soils are Typlc Quartzipsamments, and members or the great soil group of

Regosols. The white sand has little potential for cultivation, (capability class

IV), although some crops could be grown in well-watered places if all the plant nutrients were supplied. Some sites have stands of greenheart, wallaba, and other conmercial timber trees; and Caribbean pine is growing well in plantings near Bartlca. The 6500 square miles of this association, and the areas of white sand in association 7, will furnish some wood products and can be used as extensive parks and wild life refuges, but are not suitable for farming. - 86 -

Association 7, brown sandy soils, contains large areas of gently sloping sands, loamy sands, or sandy loams. Important areas lie between Ituni and

Orpulla, and large but discontinues bodies extend southward from that vicinity nearly to the southern border of the country more than 250 miles away.

Soils were classified in 16 series. The deep, brown sands are classified as Ultic Quartipsamments (Regosols). The soils that contain some clay in the subsoil are Psamnentic Udorthox (Red-Yellow-Latosols) or Oxic Normudults (Red-

Yellow Podzolic soils). Native vegetation is partly savannah grasses with extremely low potential for grazing, but mostly evergreen seasonal forest and rain forest. In the savannah areas, trees grow along drainageways and in wet places, where the soil3 are dark coloured, seasonally wet Aquipsamments,

Ochraquults, and Umbraquults (Low Humic Gley and Humic Gley soils). The well- drained brown soils that are not too sandy have good physical properties, good water holding capacities and if fertilized heavily will produce many annual crops and tree crops, and pastures of high carrying capacity, capability class

II and III.

Analytical data for Kasarama loamy sand are given in table 4. Control of runoff and of erosion are essential, even though many of the slopes are less than

3 percent. Slopes are long, and erosion takes place if water runs downhill in any unprotected channel. The brown loamy soils of this association appear to have good potential for agricultural developments; but settlers must learn to live and overcome the limitations of poor, erodible soils and erratic rainfall. Plant nutrients must be supplied in fertilizer, and mulching and other practices must be followed to conserve the nutrients and hold moisture.

Association 8 is dominated by very sandy or very gravelly soils that are mostly gently or moderately sloping, but are strongly sloping or steep in some places. The largest areas are in the southern part of the country; smaller areas - 87 - adjoin the laterite-capped mountains and hills in the north-central part, and

lie in scattered locations within the Pakaraima Mountains. The dominant soils are sandy or gravelly; skeletal Typic Haplorthents, Typic Udorthox, and Ochric

Plinthaquults are present. Great soil groups are Regosols, laterite gravelly phases, Red and Yellow Latosols, and Ground-Water Laterite soils. Vegetation is part forest and part savannah. Savannah areas of the sandy or gravelly soils

furnish grazing of poor yield and quality. The Red-Yellow Latosols and Ground-

Water laterite soils, if not too steep, can be improved with fertilizer for the growing of crops or pastures. They are in capability class III, severely limited for crops. Some shifting cultivation is practiced, mostly on edges of the

forest near the savannah.

HILLY OR ROLLING SOILS

Three associations of hilly or rolling soils make up about 34 percent of

the country. Bedrock in these areas is mostly igneous ormetamorphic rocks, consisting of granitic rocks, ridges and mountains of dark coloured basic rocks, and a considerable area of weathered phylllte, schist, mudstone, or other fine- grained, foliated rocks. Slopes are mostly hilly or rolling, with some steep hills and mountains. Elevations range from sea level to 1,000 feet, with a few higher ridges. Crusts, boulders, and gravel of ironstone are prominent wherever

the original rock contained much iron, but generally not In the areas of acidic rocks. The original rocks have been deeply weathered, and the soils are acid and low in plant nutrients. In many places the rocks or the soil materials derived from them apparently were covered with the sands and some interbedded clays of the White Sands Formation, and then were re-exposed in a later cycle or geological erosion.

Areas of white sand remain on many of the tablelands between streams, especially in a strip 40 or 50 miles wide, west of the Esaequibo River and north of the Potaro River. - 88 -

Association 9 contains hilly or rolling loarav soils and clay soil, on deeply weathered, mostly light coloured, acidic rocks; many granites and gneisses, and some fine-grained, foliated rocks. Dominant soils probably are Typic or Oxic

N0rmudults, also classified as Red-Yellow Podzolic soils and Red-Yellow Latosols.

Most of the soils are very low in plant nutrients. Dominant capability classes are II, severely limited, depending on the slope. Some contain a small amount of calcium, but all are acid and require fertilizer, lime, and careful management if crops are grown. Analytical data for two soils are given in table 4.

Slopes range from gentle to very steep. The soils are erodible, and control of runoff and erosion are essential wherever land is cleared for cultivation. This association is the dominant one in the northwestern section, north of the Pakaraima

Mountains. It probably contains at least 3,000,000 acres of soils that have gentle or moderate slopes and can be cultivated with proper management. Slopes too steep

for cultivated crops or even for tree crops are mingled with the favourable soils, and careful planning of any proposed farm land, therefore, is essential.

In association 10 are hilly, reddish clay soils that contain ironstone boulders or gravel. These soils generally are on ridges or mountains of dark-coloured, basic rocks. They are scattered throughout the northwestern and central parts of the country, and in the Pakaraima Mountain section. A small but significant area is located along the northern boundary of the Kanuky Mountains in the southwest.

Native vegetation is mostly tropical forest. Dominant soils are Oxic or possibly

Typic Rhodudults; in terms of great soil groups, Reddish-Brown Lateritic soils.

Soil texture, of the material finer than gravel, is generally clay. The amount of laterite gravel ranges from little or none to 75X or more of the soil mass.

Soils that contain more than 707. laterite gravel are classified as Regosols,

laterite gravelly phases, and probably as a clayey skeletal family of Typic

Haplorthents. Stones and boulders of hard laterite or of dark-coloured igneous - 89 - rocks, or both, are common in many of the areas. Steep and rocky soils are common. The moderate slopes that are not too rocky are in capability class II moderately limited, or Class III severely limited or class IV very severely limited

for crops.

Most of the soils have been highly leached, and when analysed contain few or no more plant nutrients than the soils of association 9. In some parts of

the Pakaraima Mountains and near the Kanuku Mountains, however, these soils contain a significant amount of exchangeable calcium and are less acid than the usual soils of the uplands. These few soils of relatively high base status are

the most fertile soils of the Interior, but they are 3teep and rocky, and they are located far from present markets or sources of fertilizer. The more extensive, more acid, low-base soils of this association produce good fruits of many kinds, but they are too steep and rocky to permit much cultivation except by hand methods. Fertilizer, lime and management to control erosion are needed to maintain production of crops with acceptable yields and quality.

Association II consists of steep or shallow soils of low fertility. They make up a large part of the southeastern tip of the country. Soils are chiefly steep, shallow, or gravelly Red-Yellow Latosols, probably Inceptic or Lithic

Udorthox, and Llthosols on granite, gneiss, or schist. These soils belong to

Land Capability Class III severely limited, Class IV very severely limited.

Vegetation is high forest, with undergrowth thick on the fine-textured soils and more sparse on the gravelly or the shallow soils. These soils have not been cul

tivated, they are infertile, and have little capability for farming.

SHALLOW OR ROCKY SOILS OF MOUNTAINS

Association 12 consists of steep, shallow, or rocky soils of the mountains and high plateaus; mostly land capability class IV. The main areas are the - 90 -

Pakaraima Mountains and Plateau in the West-central part of the country, the

Kanuku Mountains in the southwest and small mountains in the southern and central parts. Major soils are Llthosols, probably Lithic Dystrochrepts.

The most extensive kind of bedrock in the Pakaraima Plateau is thick, white sandstone of the Roraima formation. The Kanuku Mountains are mostly granite and gnelsa, with some intrusive basic rocks. Vegetation on the9e soils is variable, and probably depends greatly on the supply of moisture. Rain forest (in Fanshawe's terminology), and savannah are some of the main types. The areas have low potential for farming, but. might yield timber and other wood products, when transpprtationrbecomes available. The savannahs are suitable for extensive grazing.

The best soils of the coastal plain are limited by the need for expensive drainage. All soils of. the country, and especially those of the Interior, must have fertilizer.if crops are to be grown on the same land for several years, most of them must have lime, also. Irrigation Is needed for some crops, but the amount of water is limited and the cost of Irrigation is high. As a result, many farmers must produce the crops that can be grown with natural rainfall.

This demands careful timing of work, expert water conservation on all the sloping soils, and the risk that some crops will fail. These climatic hazards are not unique to this country, but are faced in one way or another by farmers in every part of the world.

Further development of fanning is possible and is practically certain to take place in soil association 1, 2, 4, 7, 9 and 10. Developments in the other six soil associations will of necessity be restricted to those situations in which high Inputs are practicable to overcome the natural limitations and mini- mize the risk of failure. Association 6 is unsulted for commercial farming. A few successful farms are operated on the peat or muck soils of association 3, by persons who can afford the level of management that is required and the risk that - 91 - must be taken. Land settlements and co-operative development projects are expected on associations 5, 8, 11 and 12 with the completion of the proposed hinterland road connecting the Coastlands to Brazil.

Savannahs of associations 5, 8, and 11 furnish significant grazing, and can be maintained and improved through range management that encourages the good forage plants. Forested areas of these associations should not be considered for farming developments, but might furnish timber when transportation becomes available.

Great possibilities exist for increased production of crops and livestock

In the coastal plain. Tables 1 and 2 suggest that as many as 1,000,000 acres of good or fairly good soil might be available for farming. These soils need drainage and flood control, and water might not be available to irrigate all the acreage. Cost of development, even for main drains and minimum flood control, will be substantial. The technology of producing crops on the nearly level, naturally wet or somewhat wet soils is fairly well understood by many people, but enormous improvements are still needed in use of fertilizers, in cultural prac-

tices, and In choice of high quality seed or planting stock for many of the lesser crops.

The Mabaruma - Wauna - Yarakita - Kaituma area offers exciting prospects for production of crops, but also Impressive problems in soil management. Water transportation is already available to carry produce to Georgetown and also to bring fertilizer or other supplies from Trinidad. Soils, although far from

Ideal, appear to be capable of producing many crops and pasture plants. Citrus fruits are already being produced on some of the hills of soil association 10 at Hosororo and Mabaruma.

Farming is likely to Increase south of Ituni now that the Atkinson-Mckenzie road Is connected with the existing company road to put that section within reach - 92 - of the coast. The better soils of association 7 east of the Mckenzie-Ituni road will produce many crops, but fertilizer must be used. Supplemental irrigation is desirable and might be essential for some crops. Diversified farming, with annual crops, fruit trees, and livestock therefore is required, at least within communities and preferably on individual farms. Soils too steep or otherwise not suitable for crops, fruit trees, or pasture should not be cleared. Strict control of erosion is needed, along with cover crops, green-manure crops, and mulches to shade the soil and conserve both nutrients and moisture.

The savannahs of association 7 can be prepared for the first crop more easily than the forested soils, but they lack the initial supply of plant nutrients that is obtained when the logs and branches are burned or allowed to decay.

The possibilities for expansion of agriculture In Guyana are enormous; but the technology is Intricate, and the level of management must be high. The early developers, whether they are Government agencies, cooperatives, or indi- viduals, must be openminded, flexible, willing to take risks, and willing to profit by their early mistakes. Above all, they must be willing to invest in the technical guidance that is needed. - 93 -

LITERATURE CITED

1. Applewhite, Clyde C. 1964, Soil Survey, Mahaica-Mahaicony-Abary Area. Report oil the Soil Survey project in Guyana, Volume IV, Food and Agriculture Organization of the United Nations, Rome.

2. Boldwin, Mark, Charles E. Kellog, and James Thorp. Soil Classification. In Soils and Men, Yearbook of Agriculture, 1938, United States Department of Agriculture, pps. 979-1001.

3. Braun, Eitel H.G., John Derting, and G.R. Suggett, 1964. A General Soil Map of Guyana. Report on the Soil Survey project in Guyana, Volume VII, Food and Agriculture Organization of the United Nations, Rome. Map at 1:1,000,000 scale.

4. Brinkman, Robert, 1964. Soil Survey, Canje Area. Report on the Soil Survey Project in Guyana, Volume V. Food and Agriculture Organi- zation of the United Nations, Rome.

5. Brinkman, Robert, 1964. Soil Survey, Ebini-Ituni-Kwakwani Area. Report on the Soil Survey Project in Guyana, Volume VI. Food and Agricul- ture Organization of the United Nations, Rome.

6. Cleare, L.D. 1961. The Climate of Guyana, I. Coastlands and Near Inlands Areas. Rice Storage Investigations, Publications No. I. Department of Agriculture, Guyana.

7. Crocker, C.D. 1956. Boerasirle West Soil Survey Report. Guyana, Department of Agriculture in co-operation with the University of Maryland, contractor for International Co-operation Administration, United States.

8. Derting, John F., Eital H. Gross-Braun, and G.R. Suggett 1964. Reconnais- sance Soil Survey of Guyana, (1:500,000 scale). Report on the soil survey project in Guyana, Volumes III and Ilia, Food and Agriculture Organization of the United Nations, Rome. Volume III, Part I, Northwest, by Derting and Gross-Braun, Part 2, Northwest by Derting and Gross-Braun, Part 3, Pakaraima Mountains, by Derting and Gross- Braun; Part 4, Southwest, by Suggett and Gross-Braun, and Part 5, Southwest, by Suggett and Gross-Braun.

9. Fanshawe, D.B. 1952. The Vegetation of Guyana. A Preliminary Review. Imp. for Inst. Paper No. 29, Oxford Univ.

10. Harris, S. 1961. Detailed Soil Survey of the Tapakuma Project Area. Guyana Department of Agriculture.

11. International Bank for Reconstruction and Development, 1953. The economic Development of Guyana. John Hopkins Press, Baltimore, Md. U.S.A. - 94 -

12. Kellog, Charles E, Soil Interpretation in the Soil Survey. Procesed by the Soil Conservation Service, United States Department of Agriculture, 1961. 27 pages.

13. Loxton, R.J., G.K. Rutherford and J. Spector 1958. Soil and Land Use Surveys No. 2, Guyana, the Rupununi Savannahs. Regional Research Centre of the British Caribbean at the Imperial College of Tropical Agriculture, Trinidad W.I.

14. Ramdin, Harold N. 1969. Soil Survey, Barima-Kaituma Area. Ministry of Agriculture, Guyana.

15. Ramdin, Harold N. 1964. Soil Survey, Aliki Area, Ministry of Agriculture, Forest and Lands, Guyana.

16. Ramdin, Harold N. 1964. Soil Survey, Potosi-Kamuni Area. Ministry of Agriculture, Forest and Lands, Guyana.

17. Ramdin, Harold N. and Clyde C. Applewhite 1964. Soil Survey, Tapakuma Brown Sands Area. Ministry of Agriculture, Forests and Lands, Guyana.

18. Ramdin, Harold N. and Clyde C. Applewhite, 1964. Soil Survey, Wauna- Yarakita Area. Ministry of Agriculture, Forest and Lands, Guyana.

19. Simonson, Clifford H. 1958. Reconnaissance Soil Survey of the Coastal Plain of Guyana. Processed by University of Maryland, U.S.A. and U.S. International Co-operation Administration for the Department of Agriculture, Guyana.

20. Simonson, Clifford H. 1957. Soil Survey, Blocks I and II Corentyne, Guyana. Processed by University of Maryland, U.S.A. for the Department of Agriculture, Guyana.

21. Soil Survey Staff, United States Department of Agriculture. Soil Survey Mannual. U.S. Depatment of Agriculture Handbook No. 18, 1951. 502 pp. Illus. (pages 173-188, revised, were issued as a printed supplement, May 1962) .

22. Soil Survey Staff, Soil Conservation Service. Soil Classification, A Comprehensive System, 7th Approximation. United States Department of Agriculture, 1960.

23. Stark, J., Hill, G.K. Rutherford, J. Spector, and T.A. Jones, 1959.

Soil and Land Use Surveys N0.5, Guyana 1. The Mahdla Valley, 2, The Bartica Triangle, 3, The Kamarang and Kakui Valleys; 4; A part of the Upper Mazaruni Valley, Regional Research Centre of the British Caribbean at the Imperial College of Tropical Agriculture, Trinidad,W.I.

24. Stark, J., G.K. Rutherford, J. Spector, and T.A. Jones, 1959. Soil and Land Use Surveys No. 6, Guyana; 1. The Rupununi Savannahs (continued); 2, The Intermediate Savannahs; 3, General Remarks. Regional Research Centre of the British Caribbean at the Imperial College of Tropical Agriculture, Trinidad, W.I. - 95 -

Table 1: Approximate area of general soil associations

Map Area Symbol Name square miles Percent

SOILS OF THE COASTAL PLAIN

1 Clay soils, wet 1,910 2.3 2 Silty or clay soils, moderately wet 1,670 2.0 3 Peat or muck (Pegasse) 3,220 3.9 4 Silty soils, gently sloping 410 0.1

SOILS OF THE INTERIOR FLOOD PLAINS AND LOWLANDS

5 Interior lowlands, mostly subject to flooding 6,600 8.0

SANDY SOILS. GENTLY SLOPING

6 White sand 6,500 7.9 7 Brown sandy soils, gently sloping 6,850 8.3 8 Very sandy or gravelly soils, some with clay subsoil 7,425 9.0

HILLY OR ROLLING SOILS

9 Hilly or rolling loamy soils 13,115 16.0 10 Hilly, reddish clay soils with ironstone 4,490 5.5 11 Steep sandy or gravelly soils 10,685 13.0

SHALLOW OR ROCKY SOILS OF MOUNTAINS

12 Steep, shallow or rocky soils of mountains 13.825 16,8 Total area mapped 76,700 92.8

unmapped area (no aerial photographs) 5.955 7.2 Total area 82.655 100.0 - 96 -

Table 2: General Soil groups of the Northeastern Coastal Plain.

Acres

Class I land: Few limitations if drained tm: Clay soils of moderate fertility (frontland) 575,000 If: Silty and clay soils at moderate fertility (riverain soils, large areas) 794,000

Class II Land: Moderate limitations if drained lis: Saline soils, frontland and riverain 75,000 Ilm: Clay soils, low fertility (riverain) 110,000 IIw: Silty and clay soils of moderate fertility, (riverain soils, strips along rivers) 127,000 Ilf: Silty gently sloping 3oils 260,000 IIf: Frontland clay, low fertility 57,000

Class III land: Severe limitations if drained Illm: Mostly deep pegasse (peat or muck) 338,000 Hit: Clay containing toxic sulphates 173,000

Class IV land: Tidal flats and distributed areas 21.000

Total 2.530.000

Table 3: General soil groups of the Northwestern Coastal Plain

Class I and Class II land: Few or moderate limitations I - Ilm: Clay soils of moderate fertility (frontland) Area 1 323,000 IIw: Silty soils of moderate fertility, along rivers Area 2 38,400

Class III land: Severe limitations If drained Illm: Deep pegasse (peat or muck) Area 3 1.721.600

Total 2,083,000 - 97 -

Response to Phosphorus and Potassium Fertilizers on Soybeans (Glycine max L. Merr.) along Coastal Lands at Guyana

G.C. Shuklal/

INTRODUCTION

Response of nitrogen, phosphorus and potassium on soybeans in Guyana was studied by Chesney (1969) on Arakaka clay loam soil and by Shukla C1969) on

Noverwagt clay and on Inki clay soils. The experiment carried out at C.A.S., in Spring 1969 on Gnverwagt clay soil, showed a moderate though statiscally non-significant yield response to NPK applied at a rate of 22.4 + 44,8 + 44.8 kg (N + P20g + K2O) /ha. Nitrogen or phosphorus alone did not give any- appre- ciable yield response. Response to phosphate was obtained on Arakaka clay loam soil. On the same soil a significant effect due to nitrogen and potassium was not obtained.

The present investigations' were undertaken to find out the main effects of P and K and interaction PK on the yield of two high yielding varieties of

Soybeans (240664 and F62/3977),

MATERIALS AND METHODS

Some of the physical and chemical properties of the top 15 cms. soils collected from the experimental fields of the Central Agricultural Station

(C.A.S.) and the Central Horticultural Station (C.H.S.) are given in Table I.

—t Central Agricultural Station, Mon Repo9, E.C,D, - 98 -

Table 1. Some chemical and physical properties of the top 15 cm. soils of experimental fields

Truog Total Org. Ex. cations m.e AOOg. P 0 Soil N C soil Site type PH % Z (ppm,f2 5 i) Ex. K. ' Ex. Ca. 1 Ex. MR.

C.A.S. Onver- 6.9 0.12 1.1 1.9 0.38 6.1 9.5 wagt clay C:H.S. Inki 5.0 0.20 3.7 5.1 0.46 3.0 3.8 clay

The randomised block design with four replications was used for the purpose of experiments at both the place. The treatments used were as follows:

-(1) Control (2) 34 kg P205/ha (P!> (3) 68 kg P205/ha (P2) (4) 34 kg K20/ha

(Ki) (5) 68 kg K20/ha (K2) (5) 68 kg P205/ha + 34 kg k20/ha (P2K1). Triple superphosphats and muriate of potash were used as sources of phosphorus and potassium respectively. The experiments were done in the season of Spring

1970. At C.H.S,, experiments were carried out both with varieties 240664 and F62/3977, while at C,A,S., experiment with only one variety - F62/3977 could be done.

Before planting pre-emergent weedicide, dacthal was applied at a rate of

2,27 kg per 136 litres of water,

As lime was applied to previous crop, no lijne was applied to the present crop. Inocculated seeds were sown in row widths of 45.7 cms. 018") with 2 seeds per hole, 15.2 cms. (6") apart within the row. All fertilizer was applied in single application, 5,0 cms. (2") below and 7.6 cms, (3'') away from the seed, within the row at the planting time, Seeding was done 1" (2.54 cms.) below the soil, Sevin W,P. was used whenever needs for the control of leaf - 99 - cutting insects. A net area of 49.1 s

RESULTS AND DISCUSSION

The yield of soybean, variety 240664, is reported in Table 2. The analysis of variance is given in Table 3,

Table 2. Yield of soybean variety 240664 in kg/ha at C.ff.S, in Spring, 1970

Treatment Block No. Treatment r II lit IV Treatments means +

1 Control 3241 3066 3504 3395 3301,5 a

2 34kg P205/ha (Pa) 4161 3767 4271 4402 415Q.2 b

3 68kg P205/ha (P2J 3833 3416 3110 3351 3427,5 ac

4 34kg K20/ha CKjlJ 3329 3526 2869 2628 3088.0 a

3066 3170.2 5 68kg K20/ha (K2> 3570 2957 3088 a

6 68kg P205 + 34 kg 3811 3942 3614 3811 3794,5 be

K20/ha (JP^J

+ Treatments followed by the same letter in the column do not differ significantly at 5% according to Duncan's multiple range test. - 100 -

Table 3. Analysis of variance of data in Table 2

Source of variation d.f, SS MS Observed F

Treatments 5 3327688,8 665537,7 7,95**

Block 3 136600,66 45533,55

Error 15 1255719,9 83714,66

Total 23 4720009,4

••Significant , at IX C.V, - 8,29% Standard error ("means) =• 144.66

The result show the significant effect of phosphate added at a rate of

34 kg P205/ha (P^), and of 68 kg P205/ha (P2) together with 34 kg K20/ha (K1)

on soybean yield. It is important to note here, that, treatment differences

between Pj and P2K^ themselves were not found significant.

Table 4; Yield of soybean variety F 62^3977 in kg/ha at C.H.S, in Spring, 1970

Treatment Blocks Treatment Mo. Treatment r IT nr IV means + 1 1 Control 2190 2278 2519 2738 2431,2 a

2 34kg P205/ha (Pj) 2081 31979. 3657 3570 3126.2 b

3 68kg P205/ha (P2) 2453 2628 2891 3176 2787.0 ab

4 34kg K20/ha (JCi) 2847 2212 2628 2847 2633.5 ab

5 68kg K20/ha (K2J 2935 2343 2519 2819 2654,a ab

6 68kg P205/ha + 34 3066 2957 3241 3416 3170,Q b

kg K20/ha CP-jK^)

+Treatments followed by the same letter in the column do not differ

significantly at 5% according to Duncan's multiple range test. - 101 -

Table 3. Analysis of variance of data in Table 2

Source of variation d.f. SS MS Observed F

Treatments 5 1714088 9 342817.78 3,22*

Block 3 1076662 3 358887.4

Error 15 1593688 0 106245.86

Total 23 4384439 2

* Significant at 5% C,V, - 11.6% Standard error (means) =• 162.97

The yield of dried soybean, variety F 62A3977, as found at C.H.S. along

with analysis of variance are reported in tables 4 and 5. The trend of the

treatment effects is the same as noted with the variety 240664 at C.H.S.

Accordingly the treatment means of Pj and P^j were only found to be signifi-

cantly different (at 5%) from control as tested by Duncan's multiple range test.

Table 6. yield of soybean variety F 62/3977 in kg/ha at C,A.S, in Spring, 1970

Treatment Blocks Treatment No. Treatment T IT I'll rv means

1 Control 1638 1953 2259 2385 2Q58.7 a

1 34kg P205/ha (P2) 2250 2385 2538 2610 2445.7 b

3 68kg P205/ha (P2) 2709 2331 2736 2808 2646.0 b 4 34kg I^O/ha 0^7 1710 1836 2385 1926 1964.2 a

5 68kg K20/ha (K2) 1845 2007 2412 2025 2072,2 a

6 68kg P205 + 34kg 2835 2295 2988 2502 2655,0 b KjO/ha (^Kj)

Treatments followed by Che same letter in the column do not differ

significantly at 5% according to Duncan's multiple range test. - 102 -

Table 3. Analysis of variance of data in Table 2

Source of variation d.f. SS MS Observed F 1

Treatments 5 1957959.0 391591.8 10.0**

Block 3 692037.0 230679.0

Error 15 587195.9 39146.39

Total 23 3237191.9

••Significant at 1% C.V. - 8,57% Standard error (means) = 98.92

At C.A.S, Pj, P^ and PjK^ gave significant effect over control (Tables 6 and 7). The main effects of K^ and K^ were found non-significant.

Miyasaka et al. (1964) found response to phosphorus applied to soybean on a poor soil derived from the Botucatu sandstone. No significant response was obtained to N or K. Tewari (1965) reported highest yields of soybean in his experiment from 20 lb,/acre each of N and P2O5. No response was found due to !C.

De Mooy (1965) found soybean varieties to respond significantly to K but not to

P. Small differential effects were observed among varieties. In East Pakistan, triple superphosphate at rates of up to 200 lb. per acre significantly increased dry weight of leaves and stems, and yield of seed (Islam, 1964), Dunphy, Kurtz and Howell (1966) found that more fertilizer responsive varieties tended to be the high yielding ones, Anthony C1967) and, Maples and Keogh (1969) found response to fertilizer P and K. There was no significant interaction between the effects of P and K on yields but P application in some cases intensified K - deficiency symptoms (Maples and Keogh, 1969). At Beaumont in Texas, phosphorus gave no response in comparison to positive effect noted with potash. But, at a higher level of 120 lb, - K^O/acre, bean yields were increased only on supplying additional amount of phosphate (Wood, 1969). - 103 -

SUMMARY

Phosphate applied at rates of 34 kg PjC^/ha (Pj) and/or, 68kg P^/ha (P2) on soybean, varieties 240664 and F62/3977 increased soybean yield significantly.

On further additon of 34 kg K2o/ha to 68 kg PjOg/ha, the yield obtained was not statistically different as compared to P-j or P_,

LITERATURE CITED

1. Anthony, J.L., 1967. Fertilizing soybean in the hill section of Mississippi, Bull. Miss, agric, Exp. Stn. No. 743, P. 27

2. Chesney, H.A.D,, 1969, The effect of fertilizer nitrogen, phosphorus and potassium on yield of soybean, Glycine max., on Arakaka clay loam, Guyana. Agriculture Research, Guyana. 3, 105 - 107,

3. De Mooy, C.J. 1965. Differential responses of soybean varieties to application of phosphorus, potassium and calcium carbonate materials with respect to leaf composition and yield. Iowa State University of Science and Technology. Diss. Abrstr. 26, 13,

4. Dunphy, E.J., Kurtz, L.T, and Howell, R.W., 1966. Responses of different lines of soybeans CGlycime max. L, Merrll to high levels of phosphorus and potassium fertility. Proc. Soil, Sci. Soc. Am. 30, 233 - 236.

5. Islam, A. 1964. The yield and chemical composition of soybeans as affected by three levels of complementary nutrients associated with five levels of phosphorus. Pakistan J. Soil Sci. 1, 32 - 49.

6. Maples, R. and Keogh, J.L., 1969. Soybean fertilization experiments. Rep. Ser. Ark. agric. Exp. Stn. 178, pp.19.

7. Miyasaka, S., Freire, E. S. and Mascarenhas, H.A.A., 1964. Fertilizer trials with soybeans and beans in "arentio Botucatu" soil. Bragantia 23, 44 - 45.

8. Shukla, G.C., 1969. Fertilizer Trials with soybeans. Agriculture Research, Guyana. 3, 99 - 104.

9. Tewari, G.P. 1965. Effects of nitrogen, phosphorus and potassium on flowering and yield of soybeans in Nigeria. Expl. Agric. 1, 185 - 188.

10. Wood, John, R. 1969. Soybeans in Texas Gulf Coast. The Rice Journal. 72, 33 - 34. NEW INFORMATION ABOUT DIOSCOREA TRIFIDA

(CUSH-CUSH YAM) SELECTION

L. DEGRAS, R. ARNOLIN, C. SUGARD, R. POITOUT^

The selection of Dioscorea trifida (Cush-cush yam) presented at the Vllth Meet-

ing of the Caribbean Food Crops Society (DEGRAS, 1969) has been developed. The date

published at this session may be summarized as followad.

D. trifida is the only edible american yam which stands as a staple food crop

in some places. It is also the only edible cultivated yam which give there a signifi-

cant amount of 3eeds.

As utilised once by CAMPBELL and GOODING (1962) seeds from natural hybridization

of two slightly different varieties have been sowm om 1966.

Germination reaches 40 to 50Z on the 55th day after seeding and delivered a

little more than 200 seedlings. From a first planting and a multiplication plot, 49 were retained for a micro-trial in lattice design. The mean yield was about a 30 T metric ton/ha of marketable tubers over 0,003 ha planted without staking.

The well-known prevalence of male clones in Dioscorea progenies (MARTIN, 1966) has been observed in our material. Nevertheless, the non flowering clones amount over 50J of the seedlings.

Examination of the multiplication plot and micro-trial results bring up interest in morphological underground characters and in speediness and duration of growth as clonal specificity.

Growth development duration and lenght of untuberized portion of roots appeared as valuable heriditary parameters. A partial maternal dominance in tuber form seemed obvious in our material.

— Station d' Amelioration des Plantes; Centre de Recherches Agronomiques de Antilles et de la Guyana Institut National de la Recherche Agronomique (France) - 105 -

Selection for yield from yield performance could not be assumed before the

third cultivation of new clones.

VALUABLE CHARACTERS FOR SELECTION

The following indications may be considered as intuitive or deductive pro-

posals but even in this last acceptance limitation of time, localization and varietal experimental basis must no be forgotten.

Sexuality and Yield Biology

The first examination published in 1969 denoted no relation between sexuality and any character. A new examination and more recent datas (Table I) beginning with about half the number of flowering clones make questionable such an independance.

Male clones seem to be either more diversified at first in cycle duration or less early on a mean basis than female clones. A drastic selection could account

for the identical notation in 1970.

The wide fluctuations of gross and not yield let unsatisfied with any assump-

tion from the repeated superiority (8 out of 9 cases) of female clone. At least the question remains unsolved.

Tuber Motphology

Spheroid to clavate tubers with intermediate and fasciate types has been described since the first harvest, and remain reasonable ascribed to each clone up to 1970, slight departures being due to micro or macro-ecological conditions.

Even more interesting in regard of harvesting facilities is the dispersal of tuberized root portion. The relative stability of lenght of the untuberized part

(designed as "peduncle") going from 5 to 25 cm is considered in Table II. Fair correlation coefficients are found between successive years. But the fact that between 1967 and 1969 sugnificance is not reached, supports that immediate conditions of the year before play the highest part in this character. - 106 -

Seasonal Duration of Development

This character is a combines notation of leaf canopy duration and breaking

of dormancy in the field. Its behaviour, as depicted by correlation coefficients,

is identical to that of tuber peduncle (Table II). Early clones may be harvested

within nine months.

Gross yield and Marketable Yield

The Table II give also some correlation estimations of clonal yield relative

stability between years.

The high value for 1966 x 1967 is an effect of size of seed-pieces at plan-

tation. The whole harvest of 1966 standed as seed-pieces and were highly vari-

able according to erratic situation or growth condition of primary cultivation of

the single seedling of each clone.

From these coefficients the employment of yield as a valuable estimation of

clonal productivity seems actually undue in the first culture, at least on a gross

yield basis.

Marketable yield permits a more confident approach of clonal productivity.

Indeed, the constant positive value of correlation coefficients and the fact that

each culture may be considered a new (though not entirely distinct) estimation of

the same genetical population behaviour gives an opportunity of combining the

coefficients for an accurate evaluation of the general stability of marketable yield through several years.

nsHra VESSEREAU, 1948) lead Combined estimation through z - A2 lo, gJLLl 1 - r- <

to following values: r1 1967 - 1970 » + o,22 of which probability stands between

0,05 and 0,10 (N' - 67) r' 1968 - 1970 - + 0,45 of which probability stands

between o,22 and 0.05 (N' - 18) - 107 -

Table I. - Sexuality and yield biology

Cycle duration Gross yield in Net yield in Number (mean notation) % control Z con :rol YEAR 0 o 0 o 0 o 0 o + + + +

1966 6 20 60 40

1967 6 20 1.5 3,0 55 55 92 74

1968 6 20 1,0 2,0 50 28 46 20

1969 6 10 1,0 2,0 104 95 66 46

1970 5 3 1,5 1,5 72 53 54 32

Table II. - Statiscal evaluation of relative stability of four characters through five years of I), trifida hybrid clones selective multiplication.

Cycle Tuber Gross Net X y N duration Peduncle yield yield r r r r

J966 1967 49 +0,70**

1967 1968 49 +0,37** +0,29* +0,17 +0,12

1968 1969 17 +0,69 +0,62** -0,09 +0,43(*)

1969 1970 7 -0,03 +0,53

1970 1969 17 +0,33 +0,35

(*) Probability between 0,10 and 0,05 * Probability under 0,05

** Probability under 0,02

These significative estimations are in accordance with the wall known princi-

ple that in steady selection, low value of heritability does not preclude the utilization of characters that may seem too erratic in a short time evaluation.

Two graphics (Fig. 1 and 2) give a visual scheme of the very slow shifting

of mean clonal populations yield gained in our selection. The definite progress - 108 - has been done between 1968 and 1969 cultures. The apparent shifting in popula-

tion mean for gross yield between 1967 and 1968 may be a fluctuative position of the expression of this some what versatile character.

OTHER CHARACTERS

Among other observations it must be indicated that the speediness of initial growth of vine which were considered in 1969 did not give a correlative classification of clone in successive years.

Last year, cooking quality and taste prefeeence were investigated among twelve clones. Flesh texture, coloration and firmness were included in a statiscal design operating with five tasters. In most cases clonal note dispersion were convenient. The best agronomical hybrid clone, INRA 25, found as one of the most generally appreciated.

Deseasoning ability of clone must be investigated. Indeed; a recently introduced material from French Guyana exhibited a seasonal development quite different from the usual spring to winter one. Flowering took place in March and cycle appears to be from autumn to sunnier.

The pluriannual and ecological stability of all these traits must be ascertained for their use in selection.

PROSPECT FOR D^ TRIFIDA BREEDING

The breeding of D. trifida must now take a new departure..

The hereditary nature of several traits has been observed at the second multiplication planting.

Several characters have proved a fair stability through a number of years.

Marketable yield can be considered around the third culture as a valuable estimate of clonal productivity. - 109 -

Floral biology has been investigated (DEGRAS, 1970) and though at a poor score, controlled hybrization has been obtained in 1970.

Isolated culture will bring data on genetical markers and more controlled hybrid progenies.

Nevertheless a very wide task in biological approach of this yam is always needed apart from these pragmatic efforts. What about the developmental phases of this species in regard of the schemes previously describe for a number of other species (DEGRAS, 1967, FERGUSON and HAYNES, 1970, ENYI, 1970 for instance)? What about its cytogenetical situation? We hope that in collaboration with trinidadian and puerto-rican research workers much could be added on these important lines.

SUMMARY

Seeds from two D. trifida clones give about 200 seedlings in 1966. Male clones were prevalent out of the minor number of flowering ones. 49 were selected in 1968, 17 in 1969 ahd 7 in 1970. Relations between sexuality and earliness or yield remain questionable but appeal to finer investigation. Tuber form, lengbh of untuberized portion of root (peduncle) and cycle of development exhibited a reasonable relative stability in successive years. Marketable yield took value for selection on account of 1967 to 1970 or, better, of 1968 to 1970 integrated estimates. Thus confirmed the assumption that this character could not be evaluated before the third multiplication of seedlings through tuber planting.

Cooking quality and taste preference are now considered as well as deseasoning ability of clones.

Need of thorough studies in cytogenetic and growth biology of D^ trifida is underlined. - 110 -

LITERATURE CITED

CAMPELL J.S. & GOODING H.J. 1962. Recent developments in the production of food crops in Trinidad, Trop. Agric. Trin. 39, 4, 261 - 7.

DEGRAS L.M. 1967. Growth and storage in tropical root drops. Int. Symp. Trop. Root crops. Trinidad.

DEGRAS L.M. 1969. Quelques donnees sur la varia ilite de descendance d'lgname Cousse-couche (D. trifida L.). 7th Annual Meeting of Caribbean Food Crop Society (Guadeloupe).

DEGRAS L.'M. 1970. Morphology, phisology and selection in three tropical tuber crops. Proc. of the second inter. Sympos. on tropical root and tuber crops, Hawaii.

ENYI B.A.C. 1970. Growth studies in Chinese yam (Dioscorea esculenta). Idem.

FERGUSON T.U. & HAYNES P.H. 1970. The response of yams (Dioscorea spp) to nitrogen, phosphorus, potassium, and organic fertilizers. Idem.

MARTIN F.W., 1966. Sex ratio and sex determination in Dioscorea. J. of Hereditary, 57,3,95 - 99.

VESSEREAU A. 1948. Reserches et experimentation en Agriculture, T. 2 - Methodes 3tatistiques en biologie et en agronomie. 377 pages. Baillere. Paris. - Ill -

A SEW LOOK AT PIGEON PEAS S.J.A. WILLIAMS AND J,A. SPENCfi-'

INTRODUCTION

Green pigeon peas, Cajanus cajan (t,J Millsp. has always been a favourite pea among the people of the Caribbean, traditionally planted in May-June at a spacing of 3 ft. x 5 ft,, and harvested between December and February of each year. High harvest cost, however, has tended to cripple large scale production because of • the need to harvest green pods, as they mature, over a prolonged period of time.

Within recent years a considerable amount of research at the University of the

West Indies has been conducted to alter the habit of the pigeon pea plant from one that grows to a height of 12 - 15 ft, with indeterminate podding habit, to a dwarf or semi-dwarf type (3 - 5 ft. in height) that produces determinate inflorescences with all the pods maturing more or less at the same time. These aims have been achieved by breeding C3,5J, In addition, pigeon peas are photo periodic and more specifically, short day plants, hence the later they are planted in the year, the shorter is the period from planting to flowering and the smaller the plant.

MATERIALS AND METHODS

In an attempt to facilite the mechanical production of pigeon peas, a dwarf type (variety GI 27/4A) was planted in December 1970 - January 1971 at the Field

Station U.W.I., Trinidad, after a preliminary trial in 1969 CSpence & Williams -

In press) had shown the possibility of developing such a system. The aims were to determine;

a) the feasibility of mechanical planting and harvesting;

b) the yield obtainable when pigeon peas are planted as a row crop and the entire crop is harvested all at once;

— Faculty of Agriculture, U.W.I., Trinidad. - 112 -

c) the fruiting period with planting in late DecemberrJanuary Ci.e,

the period of the year when the day length ia lengthening rather

than shortening).

In addition, through the kind cooporation of the management of International

Foods Ltd, (the company that financed the major portion of this work) portions of the crop, both in the form of plant tops plus pods, as well as pods alone were put through the viner which removes the pea from the pods.

Pigeon pea seed was sown on the 28th and 31st December 1970 and 12th and 20th

January 1971 on River Estate loam soil at distances of approximately 5 to 23 inches in the row and 18 inches between rows by means of a Massey-Ferguson row crop planter, the resulting plant population densities varying from 55,400 to 15,100 plants/acre.

This row crop spacing was used because it was standard for other row crops and in addition available inter-row cultivation equipment could be conveniently used at this setting. The different spacings within rows were used to determine the effect if varying density on yield (per plant and per acre).

Planting was on 12 ft. wide cambered beds to facilitate proper drainage, since the pigeon pea is very susceptible to water logging.

In the preliminary trial in 1969 four rows were successfully cultivated when the plants were approximately 9 inches tall with duck foot harrows mounted on a row-crop tractor. There was no damage to the crop. A pre-emergence weedicide,

Atrazine (Gesaprim 80) was applied at the rate of 2-i lb. per acre to most of the area planted in 1970/71 with good results. The latest planting in December 1970 had no pre-emergence applied, it would appear that growth, at that time and at the high densities used, was sufficiently rapid to control all weed growth.

Pod borer (Ancylostomia stercorca) was controlled with 3 applications of

Tetrachlorvwphos (Gardona) at the rate of y lb. active ingredient per acre during early pod development. This insecticide was applied with a low volume mistblower sprayer. - 113 -

Sampling for stage of maturity was determined by assessing 60 plant samples

100 days after planting and at 4 - 7 day intervals thereafter. Pods were sorted into immature, mature and dry. Fresh and dry weights were determined from these samples. Yields were determined by cutting and collecting all the pods from 1/60 of an acre plots.

Harvesting was done by the following three nethods:

1) Cutting the plants 6-10 inches above ground level

with a reciprocating mower.

2) Stripping all the pods by hand directly from the standing plants

in the field,

3) Cutting the tops of the plants with a sickle knife,

RESULTS

Table 1 shows the percentage immature, mature and dry pods for three planting dates (28 December 1970, and 12, 20 January 1971), Highest yields of mature pods occur some where between 107 and 111 days of age. At the highest yield points a mean of 63.1% of pods are mature, 2,2% of the pods are dry,

In December 1970 - January 1971 four planting dates (28 and 31 December 1970 and 12, 20 January 1971) were used and flower buds were noted in each case 60 days after planting, i. e. peak maturity occurred at 107 - 111 days after each respective planting. This now establishes that:

1) Flower buds are initiated in Trinidad on both decreasing

(Hammertan - personal comnunication)

2) Harvesting can be spread by planting at convenient intervals

during December and January, and the processing plant can

predict and regulate the flow of peas to its plant during

March, April and May. - 114 -

A comparison of yields, one computed from a 60 plant sample the other by harvesting 1/60 of an acre is shown in Table XI, The purpose of the two yield

figures was to determine the reliability of yield data from the 6Q plant sample

taken.

Table III gives an approximate indication of the time taken, and the cost

involved in harvesting, at one picking, all the pods from an acre at a plant population of 55,400 plants per acre.

The viner at International Foods Ltd, normally handles the removal of peas

from pods. The viner successfully removed peas from pod9 on the plant. This system however, is not practical because the long stem (15 - 24 inches in length) necessitated the slowing down of the elevator feeding the viner, and in addition the stems caused some damage to the canvas conveying this material through the viner. It would seem therefore, that picking will have to be restricted to stripping pods or cutting the end of branches with a sickle knife (as is done in rice) until design and construction of a mechanical harvester/elevator is completed.

Cross & Thomas (1) have shown that the total pre-harvest cost of a commercial crop of pigeon peas is $86,00 TT per acre. The pre-harvest cost of pigeon peas as a row crop is estimated to be $109,00/acre using the same rates as Cross & Thomas,

Using the values in Table 111 a comparison of the harvest cost can be made between the traditional system (at a 3 ft. x 5 ft, plant spacing) and pigeon peas grown as a row crop. While the most economical system of harvest is moving and passing the plant through the viner, cutting with a sickle knife is the most practical in view of the damage done to the vining equipment. Table IV shows that harvest cost can be greatly reduced by growing pigeon peas as a row crop (from

$147.00 to $32,00).

The gross profit, at a plant population of /55,400 plants/acre, is $270.00 with yields of 4110 lb. pod/acre as compared to $167.00 when grown in the traditional - 115 - system. A yield of 4110 lb. pod per acre yields some 2Q00 lh, of green peas per acre. Itf is possible that the profitability may be increased further as a result of a second flowering.

DISCUSSION

The above work demonstrates a new concept in pigeon pea production, and ror the first time opens new avenues for large scale, out of season production, with the following advantages:

1) It establishes, at least as far as Trinidad and Tobago is

concerned, that a dwarf cultivar developed by research workers

at St. Augustine, can be planted both in December and January

and produce yields (4000 lb. pod/acre) equal to the traditional

system, if yields at a single harvest are considered,

2) While pre-harvest cost are higher by 21% in row crop planting

system the harves costs have been reduced by some 70%,

3) Late planting allows for better land use, since planting may

be carried out during the dry season; other crops might require

irrigation.

4) Pigeon pea cropping can be extended into April and May, and

the processing plant can predict and regulate the flow of

peas to the plant at this time of the year by Che adoption of

different planting dates,

5) Regrowth of plants will allow for collection of seed for the

. following December planting.

6) Due to the shorter time to cropping the yield per acre per day

of the cropping period for pigeon peas as a row crop is 36 lbs.

as compared to 19 lbs. per acre per day for the traditional

system. - 116 -

7) The regrowth could be used as fodder if pod yields appear

uneconomical to harvest.

There is of course, much research still to be done in order to maximise yield in the row crop system. One study of interest is the development of cultivars that will produce 100% mature pods at the same time instead of only 60% as shown in this study. Table 1 shows that there is 36% immature and 4% dry pods when plants are 107 days old. It is interesting to note that if all the pods were allowed to mature, or matured all at once, the yield would be in the neighborhood of 6850 lb. pods per acre, a yield that is 2850 lb. greater than that reported by

Cross & Thomas (1).

Salette & Coubois (6) have shown that the yield from the second flowering, of a Trinidad dwarf (GI 54/3), was approximately half that obtained from the first flowering, and while we await the second flowering from our trials, it is quite likely that these yields will be about 1000 lb. pod per acre. Nevertheless, the yields herein are better than those for commercial production as reported by

Henderson (2) in Trinidad, Salette and Courbois (6) in Marie Gelante or Riollano et al (4) in Puerto Rico and compare favourably with other experimental results for a single harvest.

ACKNOWLEDGEMENTS

The authors wish to acknowledge the help given by Messrs, Ramkisson and M,

Benny in collecting and measuring samples,

REFERENCES

1. Cross, L.G, and Thomas, S.M, - Pigeon Peas, Texaco Food Crop Demonstration Farm, University of the West Indies, Trinidad. Bulletin No, 5 (1968),

2. Henderson, T,0. - 'Some Aspects of Pigeon Pea Farming in Trinidad', Occasional Series No. 3 (1965), Faculty of Agriculture, U,W,I, Trinidad,

3. Purseglove, J.W. - Tropical Crops, Dicotyledons 1, 236, (Longmans, London, 1968). - 117 -

4) Riollano, A, PSrez, A and Ramos, C, (1962) 'Effects of planting Date, Variety and Plant Population on the Flowering and Yield of Pigeon Peas', Journal of Agriculture, University of Puerto Rico, XLVI, 2 127-134,

5) Royes, W.V. In Annual Report Faculty of Agriculture 1967-68, University of the West Indies, Trinidad (1968).

6) Salette, J.E. and Courbois, J.M, 1968 - 'Agronomical Aspects of Pigeon Peas (Cajanus cajan) in Marie Gelante'. Proc. Caribbean Pood Crops Soc., TABLE 1 SAMPLE HARVEST FOR STATE OK MATURITY AS A PERCENTAGE December 1970 - January 1971 Planting

Planting Grade of Plant Age in Days Date 100 107 111 114

December Immature 8 3. 7% 33.3% 27.8% 9.5% 28, 1970 Mature 16.3% 61.1% 69.7% 62.7% Dry NIL 5.6% 2.5% 27.8%

January Immature 52.2% 35.8% 4.8% 12.9% 12, 1971 Mature 47.8% 61.0% 57.0% 56.1% Dry NIL 3.2% 38.2% 31.0%

January Immature 76.9% 40,7% 7,8% 20, 1971 Mature 23. 1% 58,5% 50.0% Dry NIL 0.8% 42.2% - 119 -

TABLE II

Pigeon pea yields as a row crop

Planting Plant Population Computed yields 1/60 acre date from 60 plant sample sample at a mean wt. of (lb./acre) 4.1 oz./plant (lb./acre)

December 55,400 4840 4110 28, 1970 - 120 -

TABLE III

The approximate time and cost of harvesting Pigeon Peas grown as a row crop with yields of 4100 lb. pod/acre.

Harvesting Operation Harvesting time Cost/acre (per acre) $TT la. Cutting the crop with a reciprocating mower 3 hours 5.40 lb. Collecting and loading plants after mowing 4 man days 16.00 2. Cutting plant tops with sickle knife 8 man days 32.00 3. Stripping all pods from plants standing in 12 man days 48.00 the field

Note on Costings

For the purpose of this paper costings are as per Cross and Thomas (1).

Labour costs: At the commercial rate of 50 cents TT per hour for

unskilled labour and 55 cents TT per hour for tractor

operators. These figures are considerably lower than

those paid at the University Field Station where Goverment

rates apply.

Tractor costs: The rates used for the tractor are $1.80 TT per hour,

and for the rotovator $1.00 TT per hour.

Materials: All materials are charged at cost. TABLE IV

Comparison of cost of product ion per acre of pigeon peas Operation Traditional system at a 3 ft. x 5 ft. spacing j , Row crop system at 18 in. x 5 in. spacing yield/acre 4000 lbs. pod— yield/acre 4110 lb. pod

$ $ 2/ Pre-harvest cost 86.00 109.00=-' 3/ Harvest cost 147.00 32.00^'

Total 233.00 141.00

Value of crop at

$0.10/lb. 400.00 411.00

Gross Profit 167.00 270.00

—^ Reference: Cross and Thomas (1)

2/ — Costings as per Gross and Thomas (1)

Harvest by sickle knife. - 122 -

Studies on coconut caterpillar, Brassolis sophoras Linnaeus and moth borer, Castnia daedalus Cramer, two major pests of coconut palm, in Guyana

B.K. Rai—^

INTRODUCTION

Coconut, Cocos nucifera is the third most important crop of Guyana and the

area under its cultivation in 1969, was estimated at 18,700 ha. Studies on two

major pests of coconut palm i.e., coconut caterpillar, Brassolis sophoras Linnaeus

(Brassolidae: Lepidoptera) and moth borer, Castnia daedalus Cramer (Castnidae:

Lepidoptera) have been carried out and are reported herein. Most of the pests of

coconut palm readily attact other species of palm (Lever, 1969) and thus studies on pests of coconut palm are also expected to be useful in cultivation of other economic palms like oil palm.

A. Braesolis sophorae, Linnaeus

B. sophorae is distributed throughout tropical South America and the dis-

tribution of its four forms is: sophorae sophorae Linn., Guianas to Soath

Brazil; B. sophorae larida Stichel, Colombia; B. sophorae vulpecules Stichel,

Paraguay and B. sophorae ardeus Stichel, South Peru (Fruhstorfer, 1924). B. sophorae sophorae i3 also recorded from Trinidad (Kaye, 1921).

Besides coconut palm, the caterpillars also feed on other palms like oil palm (Elaeis guineensis), the royal palm (Roystonea elata) and the cabbage palm

(R. oleracea); bananas; plantains and other large monocotyledons (Van Dinther,

1960).

Severely attacked coconut palms are stripped of their leaves and bare mid ribs are left. Such palms lose an entire crop of nuts and a period of 12-18 months

LI Central Agricultural Station, Mon Repos, Guyana (S.A.). - 123 -

after such attack must elapse before there is another crop, withstanding that

thera is no further infestation.

A coconut estate at De Hoop, East Coast Demerara, average height of palms

7 m., has been repeatedly infested with the coconut caterpillar since early 1969.

No control measures were undertaken. Observations in June, 1971, revealed that

about 20% palms had died and there were no mature or developing nuts on the surviv-

ing palms.

Larger caterpillar make nests up to 45 cm. long by webbing together the leaf-

lets, wherein they hide during the day. Caterpillars feed at night. Sometimes,

specially the smaller caterpillars hide about the bases of the leaves, in fibrous

material. Detailed biology and bionomics of this pest in Guyana, has been worked

out by Cleare and Squire (1934). The adult butterfly lays the eggs in masses of

100 or more, cemented to the leaves, leaf bases and fibrous material at crown.

Incubation period is 20-25 days. There are seven larval intars. Larval duration

is 76-91 days. Gregarious larvae tend to turn solitary near pupation. Pupal stage

lasts 11-14 days. Life cycle is completed in about 120 days and there are three

generations per year, starting in March - April, June - July and October -December.

Though coconut caterpillar is to be found in greater or lesser numbers every

year but now and then outbreaks occur (Cleare and Squire, 1934). An outbreak of

this pest started in 1968 and is continuing through June, 1971. A survey carried

out in June, 1969, revealed that 600 ha. aach were heavily infested in Mahaicony-

Abary and Berbice.

MATERIALS AND METHODS

Comparative toxicity of insecticides: Technical grades of insecticides were formulated as emulsions using benzene as solvent and Ratzloff PNS 737 as

emulsifier. Insecticides not soluble in benzene, were dissolved in other suitable - 124 - solvents. Coconut leaflets were dipped in emulsions for one minute and were slightly shaken to remove excess fluid. The liquid on leaflets was allowed to dry and then the leaflets were placed in glass jars. Field collected, 4th and

5th instar caterpillars were used in tests.

There were three replications of ten insects each for each treatment. Insects were introduced in jars at 4 p.m. Mortality data were recorded 48 hours later.

Corrected percentage kill was worked out by Abbots' formula (Finney, 1964).

Injection of coconut palms: In earlier stages of work, an injection appa- ratus described in Shell Chemical Bulletin BID/L/3, June, 1965 was used for injecting commercial monocrotophos 60£ E.C. into the palms. Subsequently, a hand operated chest brace drill with 0.79 cm. (5/16th inch), 0.95 cm. (3/8th inch) and 1.27 cm.

(If 2 inch) drill bits, was used. 7.6 cm. deep hole at a convenient place on the trunk, say within a metre from ground, was drilled. The hole went down and towards the centre of the trunk. An exact amount of liquid insecticide was pipetted into the hole.

RESULTS AND DISCUSSION

Comparative toxicity of insecticides: Based on the results of comparative toxicity of insecticides to the caterpillars of sophorae, an effort has been made to arrange insecticides in order of toxicity (Table I). Five insecticides which gave more than 907. kill at 0.01% concentration were: methomyl, azinphos- methyl, monocrotophos, trichlorfon and endosulfan. Out of these five insecticides, trichlorfon is suited for spraying of coconut palms in view of its comparatively low cost and greater safety to operators while monocrotophos, the only systemic insecticide, was selected for injection into the palm, for the control of the caterpillar. - 125 -

Spraying of coconut pal ma for control of the caterpillar: Spraying of infes-

ted coconut areas with trichlorfon solution at 1 kg. a.i. in 11 litres of spray

fluif/ha. from fixed wing aircraft, gave excellent control of the caterpillar.

Similarly, spraying of coconut palms with trichlorfon at 1.0 - 1.5 kg. a.i. in 20

to 30 litres of spray fluid/ha. with a tractor mounted sprayer gave an excellent

control of the caterpillar, on palms up to 12 m. high.

The specifications of the sprayer were:

Engine capacity 6.1 H.P. at 5000 r.p.m.

Air capacity 166 m''/minute.

Air speed 159 km/hr.

Nozzle open rotating dis.

Vertical swath 15-20 m.

Under conditions on the coast, with horizontal wind velocity of 5-10 kra./hr.,

the effective vertical swath of the sprayer was found to be 12 m.

Injection of coconut palms for control of the caterpillar: About 9 m. high

coconut palms, infested with the caterpillar were injected with different dosages of monocrotophos 60% E.C. and the results presented in Table III indicate that

2.A to 3.6 gm. a.i. or A to 6 ml. of 60% monocrotophos E.C. in one hole/palm, kill

all the sophorae in A days. - 126 -

Table I. Comparative toxicity of insecticides to the caterpillar of B. sophorae

Corrected percentage kill at conc. of

Insecticide 0.01% 0.003%

Methomyl 100.0 77.3 Azinphos - methyl 100.0 31.8 Monocrotophos 95.5 54.5 Trichlorfon 90.9 54.5

Endosulfan 91.3 30.4 Chlorphenvinphos 82.6 4.3 Dicrotophos 68.2 13.6 Amidithion 45.5 31.8

Fenitrothion 43.5 0.0 Aldrin 30.4 8.7 Mecarbum 31.8 4.5 Unden 18.2 0.0

Folimat 13.6 0.0 Fensulfothion 13.6 0.0 Carbaryl 9.1 4.5 Disyston 4.5 4.5

Cyolane 9.1 0.0 Heptachlor 9.1 0.0 Lindane 0.0 4.3 Phorate 0.0 0.0

Cyanamid 47470 0.0 0.0 D.D.T. 0.0 0.0 Malathion 0.0 0.0 Iodfenphos 0.0 0.0

Caynamid 47470 » 2 - (diethoxyphos - phinylimino) - 4 - methyl -

1, 3 - dithiolene. Data presented in table II indicate that out of 816 palms observed in three different typical coconut areas, 31 trees were more than 12m. high. Thus for these 31% trees, control measures alternative to use of tractor mounted sprayer, require to be found.

Table II. Data on height of coconut palms and infestation by daedalus.

Height of coconut palms (metres) Area 3-6 6-9 9-12 12 - 15 15 i i a b c a b c a b c a b c a b c

Unity 25 4.0 5.5 81 6.2 8.8 118 8.0 11.6 106 7.1 14 0 0 -

Handvelth 14 4.1 5.2 64 5.5 7.6 75 6.2 10.7 77 5.8 B 1 0 -

Grove 48 4.0 5.5 71 5.7 8.5 67 7.0 10.7 61 6.3 10 1 9 7.3 9.B

Total/mean* 87 4.0* 216 5.8 260 7.1 244 6.4 9

a « No. of palms observed b c Average height of galleries, c = Maximum height of galleries. - 128 -

Table III. Control of B. sophorae by injection of infested palms with monocrotophos.

Dos age No. of injections ' No of infested No. of palms per palm. palm treated with all caterpillars dead in no. of days after inj ection I 2 4

3.6 1 5 2 3 5

3.0 1 5 4 5 5

2.4 1 5 2 3 5

0.0 1 5 0 0 0

To determine the duration of effectiveness of injected monocrotophos to control the pest, leaflets from palms injected 72 days earlier were provided to 3rd and 4th instar caterpillars in glass jars. Data presented in Table IV indicate that both 4.8 and 3.6 gm. a.i./palm gave 100Z kill of the caterpillars in 9 days and that treatment with 4.8 gm. a.i./palm was slightly superior to that with 3.6 gm. a.i./palm. Injection of 3.6 gm. a.i./palm was effective against adult stick insect, Graeffea crouanii (Le Guillon) up to 16 weeks after tratment (Stelzer,

1970).

In May,- 1971, about 10,000 palms were successfully injected with monocrotophos to control Bj_ sophorae. The treatment was not effective in about ten old palms.

Redrilling of holes in trunks of such palms, revealed that the drilled out wood was reddish and dry in comparision to white and wet of other trees. - 129 -

Table IV. Toxicity of monocrotophos, 72 days after injection into coconut palm, to caterpillar of sophorae.

Dosage No. of injection Corrected* percentage kill No. a.i. per palm of days later. (gm.)/ palm 1 3 4 6 a 9

4.8 1 0*.0* 44.8 69.0 75.9 89.7 100.0

3.6 1 10.3 10.8 44.8 69.0 82.8 100.0

* Mortality in control was 2.5% ** Average of 3 replications of ten insects each

Residues of monocrotophos in milk and meat of mature and inniature nuts from

2 to 70 days after injection of coconut palms, (Table V) were less than 0.01 p.p.m. i.e, the detectable limit. These data were provided by the courtesy of Dr. D. E.

Chandool of the Shell Trinidad Ltd.

In view of the results reported above, injection of 3.6 gm. a.i. or 6 ml. of

60% monocrotophos E.C. in one hole per palm is recommended. 7.6 cm. deep hole made with a 0.95 cm. (3/8 inch) drill bit, in trunk, just holds 6 ml. of fluid. Thus a

7.6 cm. deep hole with a 0.95 cm. drill bit is made. Monocrotophos 60% E.C. is filled in the hole, with the help of a plastic bottle, stoppered with a rubber cork having a metal tube. This bottle is tilted, the metal tube opening is inserted into the hole and the bottle is gently squeezed to fill the hole with the insecticide.

One man can inject 150 to 170 palms per day or can treat about 1.3 ha. per day.

The cost of insecticides is G. $1.00 for 16 palms.

Suitability of the three techniques of control of the coconut caterpillar:

Collection and destruction of nests from palms is not only difficult but those caterpillar which hide in the leaf bases, are left on the palms. - 130 -

Data presented in Table VI indicate that generally the pest is destructive from March to September. At any one time during this period, almost all stages of the pest could be found in field. When aerial or ground spraying is carried out, no doubt caterpillars get killed and there is relief for sometime but the pest reappears because other stages of the pest survive. Two times i.e., in

March and August, 1969 (Table VI), all the infested area was aerially sprayed but yet the pest continued unabated, because of the overlapping generations.

Table V. Data on residues of monocrotophos in coconut' milk and meat .(Provided by Shell Trinidad Ltd).

Quantity of Treatment to Residues in ppm. monocrotophos sampling in- Meat injected/palm terval in Milk (gm.) days Mature Immature

3.6 2 0.01 0.01 0.01 3.6 7 0.01 0.01 0.01 3.6 14 0.01 0.01 0.01

3.6 28 0.01 0.01 0.01

3.6 70 0.01 0.01 0.01

0 2,7,14,28,70 0.01 0.01 0.01

Analysis carried out by G.L.C. flame photometric detector. The detectable limit wa3 0.01 ppm.

Under these circumstances, an effective treatment should be long lasting.

Injected monocrotophos remains toxic to the caterpillars for at least up to 72 days and is thus ideally suited. Excessive height of some palms, horizontal winds of 5 -

10 km./hr., camber bed system of layout of estates and establishment of drop nut palms, make the use tractor mounted sprayer impossible in most of the estates. In estates where it could be used, it can treat only 5 ha./per day with the help of two men, due to the above mentioned difficulties. The sprayer only costs about

G $3,000.00 Four persons can inject 5 ha. per day and four hand drills cost G.

$76.00. - 131 -

Unlike other crop pests, the coconut caterpillar does not come in contact with poison when the palms are sprayed in day time since the caterpillars are hidden in nests or in the fiberous material at leaf bases. The caterpillar comes into contact with poison at night when they come out to feed on foliage: Rains between spraying and feeding time, can wash out the insecticide from palm and reduce the efficacy of treatment. Heavy rains in May-June, restricted the spraying operations.

Table VI. Incidence of coconut caterpillar.

These data are from an estate where about 300 ha. were infested, out of a total of 650 ha.

No. of nests collected MONTH 1968 1969* 1970** 1971***

January 0 0 0 0 February 0 0 0 95 March 2,693 10,032 1,009 April 2,715 11,232 1,050

May 2,310 12,199 1,060 June 3,533 38,575 1,930 July 2,214 5,787 0 August 0 27,783 1,101

September 250 4,765 479 October 0 0 0 November 0 0 0 December 4,335 0 0 In 1969, additionally, 324 ha. each were sprayed aerially with insecticide, in March and August.

** In 1970, additionally, 220 ha. were sprayed with insecticide from tractor mounted sprayer.

*** In 1971, additionally, from March to May; 150 ha. were sprayed from tractor mounted sprayer and in May, about 6000 palms (43 ha.) were injected with monocrotophos. (Injection technique was given out only in May, 1971). - 132 -

The following insect parasites of B. sophorae have been recorded from

Guyana by Cleare and Squire (1934):-

(i) Telenomus nigrocoxalis Ashm. and Anastatus reduvii How, parasitize

the eggs.

(ii) Chaetolyga pyrrhopyga Wied parasitizes the caterpillar,

(iii) Spilochalcis morleyi Ashn., Brachymeria incerta Cress, and B^ annulata

F. parasitize the pupae.

The eggs and pupal parasites are very effective and parasitize the respective hosts up to 70 and 30 percent respectively. According to Cleare and Squire

(1934), these natural enemies play a very important part in determing the prevalence of the pest and to a great extent determine the occurrence of outbreaks of the caterpillar. In view of the importance of natural enemies, injection rather than spraying of palms with insecticides, suggests itself.

13. Castnia daedalus Cramer

C. daedalus is distributed from Amazone valley through the Guianas to Panama

(Van Dinther, 1960). Besides coconut palm, it also infests oil palm (stachel, 1944) and other ornamental palms like royal palm, Maximiliana maripa, Pritchardia pacifica,

Phoenix dactylifera, Livistona sp. and Sabal sp. (Van Dinther, 1960).

Creamy white, young larvae, tunnel rather shallow into the leaf stalks and adjacent part3 of trunk. Gradually, the larvae penetrate deeper into these parts.

Holes and tunnels in the trunk, run horizontally to a depth of 5 - 10 cm. and con- tinue vertically upwards. Tunnels by several larvae may unite. Because of the nature of attack, the lower leaves droop to an almost vertical position and are shed prematurely. Palms attacked year after year, may survive but when larvae bore into growing tip, the palm invariably dies.

The female moths, lay spindle shaped pink eggs, 4.3 to 4.7 m. long, near base of the coconut crown. The eggs are deposited in groups of 2 - 8. The records - 133 -

of rearing of this insect in Guyana, in 1929, by L.D. Cleare indicate the duration

of various stages to be:

Eggs stage 17 days.

Larval stage 10 1/2 months

Pupal 3tage 35 days

According to Reyne (1929), the complete period of larval development is

about one year. Pupation takes place in a 7.0 - 10.5 cm. long, brown cocoon, com-

posed of fibrous wood chips. The cocoon is often found in a shallow excavation on

the inner side of leaf base.

Heights of palm and infestation by C. daedalus: The coconut palm becomes valnerable at the age of 4 - 5 years i.e, when formation of trunk starts. The tree may then be attacked for the rest of the life (Van Dinther, 1960). A survey carried out at East Coast of Demerara (Table II) indicates that in 6 - 9, 9 - 12 and 12 - 15 m. high palms, the average heights of highest Castnia galleries were 5.8, 7.1 and

6.4 m. respectively. These data suggest that Castnia prefers palms up to 7 m. high.

In this survey, the highest gallery of Castnia was observed at a height of 14 m.

Extent of infestation and loss due to C. daedalus: 250 palms each from five coconut areas on East Coast Demerara, were observed for presence or absence of

Castnia holes on trunks and the data collected are presented in Table VII which indicate that 46 % palms were attacked by Castnia at some stage of their life. A similar figure was 85Z at Lesbeholden, Corentyne. - 134 -

Table VII. Extent of infestation of coconut palms due to C. daedalus at East Coast Demerara

No; of palms Percent palms Area observed Infested

De Hoop 250 41

Good Hope 250 42

Handenveldt 250 50

Lancaster 250 46

Unity 250 49

Average - 46

For studying the extent of loss caused by Castnia, number of nuts was counted

from 20 infested and 20 uninfested palms, in proximity of each other and of comparable height. There was an error of 5 - 10% in counting the number of nuts on the palms. The data presented in Table VIII indicate that:

(i) The infested palms bear nuts in button stage about 85% as much as

uninfested ones.

(ii) At East Coast Demerara, the proportion of semi-mature plus mature nuts

to nuts in button stage was 0.92 for uninfested trees against 0.75 for

infested trees. Similar figures for Lesbeholden were 0.73 and 0.54

respectively. These data suggest that a larger proportion of nuts drop

during maturation process in the infested than in uninfested palms,

(iii) Infested plans bear 68% and 54% as much semi-mature plus mature nuts as

the uninfested ones, at East Coast Demerara and Lesbeholden respecti-

vely. Further, the size of nuts is also reduced, due to Castnia

infestation. - 135 -

Control C. caedaj^us: During studies on the control of sophorae by

injecting coconut palins with monocrotophos, some larvas of Castnia were also ob-

served to have died. Detailed experiments were then carried out to find Che dosage

of monocrotophos and number of injeccion required per palm, for control of this

pesc. The technique of injeccion was same as for B. sophorae. Castnia holes/'

galleries jusc below the oldesc leaf indicated thac Che palm was then infested

and was Chus selecced for treaCmenC. Two weeks after treatmenc, cen lower leaves were removed and leaf bases and crunk were observed for live and dead Castnia.

The data collected are presented in Table IX which indicated thac:

(i) 3 or 4 injections per palm result in more kill Chan 1 or 2

injeccions at any one dosage of coxicanc.

(ii) 3.6 to 6.0 gin. monocrotophos in 3 injeccions per palm, give

almosc 100% kill of the Cascnia, located deep in cissues.

Van Dinther (1960) reported spraying of Che crown base with 0.5% emulsion

of DDT, aldrin or dieldrin and Anon. (1959) recommended spraying of centre of

crown wich 1% dieldrin emulsion ac 2.2 litres per palm, for concrol of chis pest.

These creacments only concrol Che newly hatched and young larvae which have not

penetrated deep into the tissues.

In view of Chese resulcs, injection of 4.8 gm. a.i. or 3 ml. of 60% monocro-

cophos E.C. ac three poincs discribuced around the crunk, is recommended. 7.6 cm.

deep hole made with 0.79 cm. (5%16th inch) drill bit, in Crunk, holds 4.5 ml. of

fluid. Three holes will hold 13.5 ml. of fluid. Since, only 8 ml. of 60% monocro-

tophos E.C. is to be applied per palm, chis insecticidal formulation is diluted with waCer in proportion of 16 pares of inseccicide and 11 pares of wacer. The diluted inseccicide is Chen used to fill che chree holes which will give a dosage of 60% monocrocophos or 4.8 gm. a.i./palm. One man can inject 100-120 palms per day. The cost of insecticide is G. $1.00 for 12 palms. - 136 -

About 5,000 palms were successfully injected with monocrotophos to control

daedalus. specially at LesBeholden, Corentyne. During these large scale operations, it was observed that some borer larvas, in bases of leaves which had got partially detached from trunk, did not die. In view of this it is felt that drooping leaves which could be easily pulled off the palms, should be removed and burnt.

SUMMARY

Coconut caterpillar, Brassolis sophorae Linnaeus and moth borer, Castnia daedalus Cramer are two major pests of coconut palm, in Guyana. Continous stripping of leaves by the caterpillar results in death of some palms while the others do not bear any nuts. Laboratory studies on comparative toxicity of 24 insecticides to the caterpillar indicated that methomyl, azinphos-methyl, monocrotophos trichlorfon and endosulfan were more toxic than the rest. Spraying of trichlorfon at 1.0 kg. a.i. in 11 litres and 1.0- 1.5 kg. a.i. in 20-30 litres of spray fluid/ ha. from aircraft, and tractor mounted sprayer respectively, gave immediate control of the caterpillar but the pest infestation continued because of overlapping generations. Injection of 3.6 gm. a.i. or 6 ml. of 60% monocrotophos E.C. in one hole/ palm, gave complete kill of the caterpillar. The treatment was effective for at least 72 days and was thus ideally suited to control overlapping generations of the pest. Further, in view of the natural abundance of insect parasites, injection rather than spraying of palms with insecticide, suggests itself. One man can inject 150-170 palms (1.3 ha.)/ day with the help of a hand operated, chest brace drill. About 10,000 palms were successfully treated for the caterpillar control.

Moth borer, Castnia tunnels the trunk near to leaf bases. As a result the leaves droop almost vertically. Egg, larval and pupal stages last for 17 days,

10 1/2 month and 35 days respectively. It prefers palms up to 7 m. high. It infested 462 and 85% of palms in two different areas. The infested palms bear - 137 - semimature plus mature nuts up to 54£ as much as uninfested palms. Injection of

4.8 gm. a.i. or 8 ml. of 60% monocrotophos E.C. at three points around the trunk, results in kill of the borer, in situ. One man can inject 100-120 palms/day.

5,000 palms we successfully injected for its control.

REFERENCES

Anon. 1959. Two important pests of coconut and their control. Farm J. 20 (2); 10,11 and 15.

Cleare, L.D. and Squire, F.A. 1934. The coconut caterpillar, Brassolxs sophorae

L. (Lep. Brassolidae) in British Guiana. Agric. J. Brit. Guiana, 5: 164-199.

Finney, D.J. 1964. Probit Analysis. A statistical treatment of the sigmoid response curve. Cambridge University Press, pp. 305.

Fruhstorfer, H. 1924. Brassolidae. In Seitz Macrolepidoptera of the World. The American Rhopalocera, 5: 285-332.

Kaye, W.J. 1921. A catalogue of the Trinidad Lepidoptera, Rhopalocera (Butterflies). Memmoirs Dept. Agric., Trinidad and Tobago, No. 2.

Lever, R.J.A.W. 1969. Pests of the coconut palm. F.A.O. Agriculinr.il StnJu-a, No. 77.

Stachel, G. 1944. De nuttige planten van Suriname. Bull. Dept. Landbouwproefsta- tion Suriname, No. 59

Stelzer, M.J. 1970. Preliminary studies on the control of the coconut stick insect, Graeffea crouanii (Le Guillou), with systemic insecticides. Bull. ent Res., 60 (1):49 - 52. - 138 -

CONTRIBUTION OF AGRICULTURE TO GUYANA'S ECONOMY

BASIL A.T. PHILLIPS^

INTRODUCTION

This short paper is intended for agriculturalists rather than for

economists and therefore avoids any serious attempt to examine economic

theories of development and the arguments for and against the importance

of agriculture versus industrialization in the development of a country

such as Guyana. The position is that we Guyanese, recognize our dependance at this stage of our development, upon agriculture and our other primary

resources--minerals and forests--to act as leading strings in the harmony

of progress which we are attempting to compose. Out of these primary products we shall create the industries which we know will accelerate our economic growth and development. We can, for example, use the foreign exchange earned from our exports of agricultural products and other raw materials to finance the importation of capital equipment for the manufac-

turing sector and while we appreciate that the terms of trade are usually unfavourable to primary producing countries, we are in the fortunate posi-

tion that our primary producing enterprises are now being so structured that the main harmful features of resource aspects of development such as the

latifundia, the heavy repatriation of profits and the absence of any signi-

ficant spill-over effects or linkages, which have inhibited development in

1/ Assistant Chief Co-operatives Officer (Agriculture). - 139 - in many parts cf Latin America, are being eliminated here. In Guyana, unlike many other territories in the Caribbean, most of the land still belongs to the State and Guyanese land will be developed by Guyanese for the benefit of Guyanese.

THE POSITION - PAST AND PRESENT

1. THE LAND

Guyana, South America's most recent Republic, has an area of

83,000 square miles and a population of about 750,000, most of whom

occupy a strip of coastland, ten to twenty miles deep, between the

Pomeroon River in Essequibo and the Corentyne River, Guyana's Eastern

boundary with Surinam.

Guyana is therefore, an empty country and even if the unpopulated

hinterland contains considerable areas of old mineral-bearing crystal-

line rocks, non-agricultural silica and very shallow gravelly clays

on steep hillsides, there remain hundreds of thousands of acres of

unoccupied soils of moderate to excellent fertility throughout the

length and breadth of the country.

The extent of agricultural sector in the country is yet to be

ascertained correctly. What are generally considered very conservative

estimates, place the figure at between 1,000,000 and 1,500,000 acres.

Of this it was estimated that less than 500,000 acres were more or

less beneficially cropped at the end of 1970. In other words only

0.7 of an acre was occupied by crops for each head of the population.

2. IMPORTS

The country imports relatively large quantities of food estimated

at about 30 percent of all foods consumed. Imports of some major food

items during 1970 are shown in Table I. - 140 -

TABLE 1. IMPORTS OF SOME SELECTED AGRICULTURAL COMMODITIES, 19701/

COMMODITIES UNIT QUANTITY VALUE

Onions lbs. 4,689,083 $ 795,478

Carrot s II 184,051 54,742

Peanuts It 663,570 260,838

Cabbcges M 281,640 60,804

Orange Juice gals. 60,180 121,312

Tomafoes lbs. 49,745 18,522

Black pepper H 63,343 53,851

Ginger n 16,883 17,136

Tapioca II 224,512 36,106

Cocoa Powder it 87,008 102,251

Turmeric • i 76,546 39,062

Tomato Paste t! 448,105 224,584

Castor Oil I» 5,670 5,435

Blackeye Peas II 90,000 22,725

Split Peas II 6,113,854 918,196

Other peas and beans II 1,466,534 354,993

Corn (Maize unmilled) II 12,074,391 990,721

1/ Source: Ministry of Agriculture - 141 -

It 1s seen therfore that perhaps the first task of agriculture

in Guyana is to feed the Guyanese nation more adequately than it does

at present. All of the commodities listed above can be produced

locally.

3. LABOUR

The 1965 manpower survey revealed that of the working population

of 166,000, 35 percent found employment in agriculture while about 20

percent of the labour force could not find jobs in any sector. The

agricultural sector is the one on which the country must depend, for

the time being, to absorb the large number of persons who want jobs but

can find none.

4. CONTRIBUTION TO THE GROSS DOMESTIC PRODUCT

Agriculture's contribution to the Gross Domestic Product from 1960

to 1969 is shown in Table II and can be compared with the contribution

of the other sectors.

It is true that as a country develops agriculture's contribution

to the Domestic Product declines relative to the contribution of che

industrial sector. But there is invariably an increase, in absolute

terms. Income elasticity of demand for food is usually high in develop-

ing countries and the agricultural sector must be prepared to cater for

its demand as well as for the demand for food of a growing population.

It is obvious from the table II that apart from sugar aria live-

stock, there has been little significant growth since 1960. Production

in the other agricultural sections has been erratic.

Discussing the contribution of agriculture to the growth rate in

1969, the "Economic Survey of Guyana" published by the Ministry of - 142 -

TABLE II. GROSS DOMESTIC PRODUCT 1960-1969'J-^

PRODUCT I960 1961 1962 1963 1964 1965 1966 1967 1968 1969

Sugar *6.3 50.0 5:.: 69.5 44.4 47.8 42.8 52.3 50.5 59.0

Rice 13.9 15.7 15.1 13.1 20.4 20.6 19.5 15.9 17.0 14.0

Livestock 3.4 6.9 9.8 6.9 8.4 8.5 7.5 8.5 9.2 10.0

Other agriculture 8.8 9.2 9.7 7.3 8.4 9.4 10.0 10.7 11.6 13.0

"ishin? 4.2 • p 6.: 5.8 6.5 7.8 8.8 9.1 8.5 7.0

Total agriculture 76.6 S7.6 93.0 102.6 88.1 94.1 88.6 96.5 96.8 103.0

Forestry 6.6 6.9 6.4 4.3 4.9 5.2 6.8 5.4 6.5 9.0

Mining and Ouarrvlng 29.1 37.3 49.9 35.8 53.5 54.0 58.9 66.5 79.6 90.0 rood ft Tobacco 5.7 6.6 7.1 8.3 11.1 12.8 13.5 14.5 15.7 17.0

Other manu- facturer 8.2 8.3 9.5 7.S 8.9 12.1 12.7 H. 1 16.3 17.0

Distribution 37.: 39.2 36.6 36.7 39.1 39.4 42.1 44.7 45.2 47.0

Transport & Conroun Ica- tions 19. 8 21.8 20.1 18.1 19.9 21.3 23.7 24.6 26.6 28.0

Engineering • Construc- tion 25.0 20.8 20.8 13.8 15.1 17.1 21.8 25.3 30.4 34.0

Reot & Dwellings 8.2 8.4 8.5 8.7 8.3 8.5 9.0 9.5 9.8 10.0

"irmncia 1 Services 5.5 9.1 9.0 8.7 9.0 9.6 11.1 11.6 11.8 12.0

"'ther services 13.1 13.2 13.7 12.3 12.7 13.9 15.1 15.7 16.1 16.0

Government 25.6 30.5 30.5 28.1 32.8 40.2 43.7 50.1 51.9 57.0

G.D.P. at Factor Cost 263.5 289.8 307.: 275." 392.9 328.3 347.0 378.5 406.7 440.0

Agriculture as a of G.D.P. 29.1 30.2 30.3 37.3 29.1 28.7 25.e 25.5 23.8 23.4

1/ The 1967 figures are revised; 1968 and 1969 estimates are first approximations.

2/ Source: Bank of Guyana Econoaic Bulletin - No. U - 1970. - 143 -

Economic Development stated: "The contribution of the Agricultural

Sector to Gross Domestic Product increased in 1969. The indications

are that the sector expanded by at least 11 percent since 1968, though

there was evidence of relative stagnation in the sector if sugarcane

is excluded. Sugarcane experienced a good year—congenial weather con-

ditions, and a year free of any major industrial relations conflict.

There was therefore a substantial increase in sugarcane harvested.

Rice, however, had another disappointing year, with low output. Live-

stock rearing, particularly poultry was still expanding in response to

a steadily increasing local demand. As the component parts of the sector

made only small gains growth in Agriculture was disappointing compared

with other productive sectors".

5. ECONOMIC CHARACTERISTICS:

The main economic characteristics of agriculture in Guyana are:

(i) Agriculture is dominated by two crops - sugar and rice which

together occupy about 86.2 percent of the crop-land and com-

prise the only significant agricultural exports.

(11) Per acre productivity is low. In the case of sugar the per

acre productivity has been considerably greater than that

of rice.

The position in 1969 Is shown In Table III.

TABLE III. COMPARATIVE PRODUCTIVITY OF LAND UNDER SUGAR AND RICE - 1969

7. of Crop- Average Yield Estimated land per Acre Value

Sugar 23.7 29.0 tons canes $ 290.001/ Rice 62.5 0.6 tons paddy 60.00l2/

1/ Yield and value calculated for small farmers only.

2/ Based on the price of Grade C paddy. Source: Ministry of Agriculture - 144 -

(111) Per capita productivity Is also low.

In 1965 the persons employed in the agricultural sec-

tor contributed G $94.1 m to the gross domestic product

with a per capita contribution of G $1,600: compared with

about $2,000.00 per capita for the total working population.

It is not surprising that per capita contribution should

be lower in the case of agriculture than In the case of the

other sectors since industry is normally assisted by a con-

siderable amount of capital but what'is important to note

is that the Guyanese economy at present hinges firmly on

primary products derived mainly from agriculture, mining

and forestry. Of these, agriculture is the dominant sector

and weakness in agriculture will depress the per capita,

income of the population as a whole,

(iv) Processing of agricultural crops is limited almost exclusively

to the milling of sugarcane and of paddy and of copra. Only

a little bit Is done in other fields, e.g., fruit canning,

the making of jams and Jellies and of livestock feeds and

corn meal.

The characteristics of the agricultural sector have resulted from his- torical rather than ecological factors. The country has been a former colony of the British Empire and the dominant agricultural crop, sugarcane, has been mainly in the hands of the expatriate plantation owners interested in little else than the profitable exploitation of their sugar estates and in fact so jealous of their monopsonistic position in the labour market that they actively stifled efforts at development in other directions. - 145 -

The agricultural workers imported to the country as slaves from Africa or indentured servants from Madeira or Asia brought with them their traditional crops and the low standards of technology associated with the level of development of their native countries.

There has been a good deal done to improve standards but, for one thing, most of the efforts expended so far have been spent on sugar and rice rather than other crops to which both soil and climate are suitable and, for another thing, the thrust has been half-hearted rather than full-blooded. More attention has been paid to some links in the chain, to research, transportation and water control for example, than to other links such as agricultural credit, the organization of a top notch extension service and to marketing.

The result has been that the programme of diversification has only just started to roll. For the first time a bold step has been taken to break away from the clutches of the two-crop economy and for the first time too a comprehensive beef cattle development programme, backed by careful planning and a reasonable amount of credit, has been launched.

Much more remains to be done. The extension arm of the Ministry of

Agriculture needs to be strengthened and recruited by a band of well prepared and dedicated officers but this improvement will only take place if young officers join the service and look forward to salaries and conditions of work comparable to those enjoyed by their counterparts serving in other

Government departments. Credit must be available to provide the means whereby farmers can benefit from the improved technology translated to them from research by the extension service. Marketing activities need to be extended, possibly along cooperative lines, but in any case much more research in handling, transporting and holding of locally produced foods, - 146 - in tastes and attitudes of local consumers, in the processing of local farm products especially fruits and vegetables, and in the requirements of markets in the Caribbean and beyond has to be carried on.

THE FUTURE

We do not seek a primum mobile, other than hard work, for our economic growth. Nor do we have to join the controversy between the protagonists of the theory of balanced growth on the one hand and those of the school of unbalanced growth on the other. We are aware as Hirschman (1) puts it that

"development depends not so much on finding optimal combinations for given resources and factors of production as on calling forth and enlisting for development purposes, resources and abilities that are hidden, scattered and badly utilized".

We can take it from here. There is no lack in Guyana of the land to grow the crops and the men to work the land. If the institutional factors, some of which have been mentioned above, are overcome, there seems to be no reason why agriculture cannot fulfill its rightful role as the pivot around which our development will turn. If we do not yet possess the technology, we can import it. In fact our technologists may need little more than greater exposure to the practical problems of applying the new techniques they have already acquired from their training In institutions at home or abroad. We have been learning too, no doubt stimulated by our recently won independence, to rely more and more on our own resources and this new self- reliance and self-confidence Is being reflected in our plans to Increase our production of corn and sorghum, of soyabeans and peanuts, of pineapples and cashew nuts. - 147 -

Writing about the functions of agriculture In development, Kindleberger (3)

notes that "agriculture can play a variety of roles in economic development,

and not just sit back while the development process spurs industry. In the

first place, it can provide workers to industry. Second, it can furnish demand for industrial output. Third, it can provide savings for use in industry or by Government in forming social overhead capital. Fourth, it may pay taxes to government, rather than lend to it. Fifth, agriculture can earn foreign exchange through exports to pay for imported capital equipment and raw materials needed in other sectors. Sixth, it can supply food for consumption by workers in industry or in capital formation. The more efficient agriculture is, the better it can perform these various functions".

It is true that some of these functions are competitive rather than complementary but what is relevant here is the accent placed upon the need for

increasing the efficiency of agricultural production. D. Gale Johnson (2) has observed that while agriculture has made highly significant contributions to the growth of the economy of developing countries, the contributions depend upon a more or less continuous increase in productivity per worker without which output in the non-agricultural sectors cannot be expanded.

And so we come back to where I started. The contribution of agriculture to the future development of Guyana will depend upon agriculturists rather

than upon economists. Agriculture's contribution via creating more jobs for our unemployed, feeding our own people better, reducing our imports of food thereby assisting our balance of payments position, earning more foreign exchange through increased exports, and producing raw materials for manufacture, will depend in the final analysis upon increasing the productivity of agriculture through increased efficiency. In other words our concern

at this stage of our development is to get agriculture moving. - 148 -

I think that I can close In no better way than to quote Mosher (4) :

"We have seen that when we talk about a progressive agriculture we are not

talking just about cultivating land and tending livestock. Instead, we are

forced to speak of roads and price relationships and research organizations

and trade and governmental policies. We must think of industrialization and

the form it takes, education and its content, banking, laws and administrative

efficiency in governmental departments."... to achieve agricultural.development thousands of people must concentrate on managing farm businesses, cul-

tivating crops and tending livestock. Other thousands must operate marketing

facilities that bring farm supplies and equipment to farms and more farm products from farms, protect them, transport them, and make them available where consumers can use them. Hundreds of people must concentrate on con-

tinuously finding more and more productive methods of farming either by

importation or by development through research. Thousands must be employed

in manufacturing farm supplies and equipment, in education for development, and in providing production credit".

REFERENCES

1. Hirschman, Albert 0., "The Strategy of Economic Development".

2. Johnson, D. Gale, "The Role of Agriculture in Economic Development" from Clawson, Marion (Ed.), "National Resources and International Development".

3. Kindleberger, C.P., "Economic Development".

4. Mosher, A.T., "Getting Agriculture Moving".

Also consulted Bank of Guyana - Economic Bulletin No. 4, 1970 Ministry of Economic Development - Economic Survey, 1969. Ministry of labour, Manpower Survey Report, 1965. - 149 -

Performance of Soybeans (Glycine max (L.) Merrill CV 'Jupiter') in Guyana as Affected by Inoculum (Rhizobium japonlcum) and Nitrogen

H.A.D. Chesney, M.S. Khan & S. Bissessari^

INTRODUCTION

Soybeans (Glycine max (L.) Merrill is a relatively new crop for tropical countries, especially those like Guyana (Latitude 5°N) that are relatively near to the Equator. As such there is very little information as to the factors influencing its performance in these areas. In the southern

United States inoculation of soybean seeds with cultures of the bacterium

Rhizobium japonicum has caused increases in yield (Caldwell and Vest (1970),

Abel and Erdman (1964), percentage protein in the seed, root nodulation and fresch plant weight and a decrease in percentage oil in the seed (Abel and

Erdman, 1964). Jacob and von Uexkiill (1963) have stated that a light dressing of N at planting produces increased yields.

The study reported here was designed to obtain preliminary indications on the effect of seed inoculation, nitrogen fertilization and their interaction on the performance of soybeans Var. 'Jupiter' on two soil types in

Guyana.

MATERIALS AND METHODS

Soils

The experiments were located at the Central Agricultural Station, Mon

Repos, in the coastal region and the Matthews' Ridge Sub-station in the

North West region of Guyana. The soil types at Mon Repos and Matthews'

Ridge were Onverwagt clay, sandy substratum—a low humic gley (Typic

1/ Ministry of Agriculture, Guyana. - 150 -

Ochraqualfs), and Arakaka clay loam—a red yellow podzol, Oxic Normudult—

respectively (Ramdin, 1966; Ramdin, 1969). Some chemical and physical

characteristics of the top 15 cm of these soils are presented in Table 1.

Table 1. Some Chemical and Physical Properti 6S of the Top 15 cm of Arakaka Silt Loam and Onverwagt Clay (sandy substratum).

Particle size % Or- 7. Fruog m.e./lOO g. Distribution (7.) Soil PH ganic Total P(ppm) PBS* matter N p2o5 CEC# Ca Ms K Sand Silt Clay

Arakaka silt Loam 4.6 4.1 0.2 1 81 2.7 0.5 0.5 0.4 35 37 28

Onverwagt clay, (Sandy substratum) 5.0 2.1 0.1 10 98 22.1 3.6 17.9 0.4 1 51 48

* PBS - Percent Base Saturation # CEC = Cation Exchange Capacity

Experimental Design and Field Procedures

The experiment was of a split-plot design with rates of N as the whole units

and rates of Inoculum as the subunits. The whole units were arranged in a ran-

domized block design and the subunits randomized within the whole units. Sub-

plot size was 7.2 x 3.6 m at Matthews' Ridge and 5.7 x 4.5 m at Mon Repos.

The levels of N (iiq, n^, n2 and n^) were 0, 16, 32 and 48 kg N per ha,

respectively. The levels of inocula (lg, and i2) were 0, 224 nd 448 g. per

kg of seed, respectively; i^ represents the recommended commercial rate. All

plots received the equivalent of 88 kg/ha of P20j and K20 each. At Matthews'

Ridge, the plots were limed at 2,200 kg/ha with dolomitic limestone to bring

soil pH to approximately 6.5; liming was not done at Mbn Repos as the soil pH

was already 6.0. The fertilizer sources used were ammonium sulphate, triple - 151 - superphosphate and muriate of potash for N, P and K, respectively. The inoculant used was commercial type 'Nitragin' which is an 'S' culture of a mixture of strains of R. japonicum in a peatbase medium.

At both sites, soybeans were never planted before and at Matthews' Ridge the land was previously forested. Inoculated seeds (two per hole) were planted by hand at a spacing of 45 cm between rows and 15 cm within the row. Inocula- tion of the seeds was done by sprinkling the relevant weights of inocula on seed which were previously moistened with a weak sugar solution. The inocula were then distributed thoroughly among the seeds by rotating the container.

Seeds were planted Immediately after. All of the fertilizer was applied at planting 5 cm to the side and below the seed.

At planting the soil was treated with the pre-emergent weedicide 'Dacthal' at 5.4 kg/ha. Control of insects was done as required using 'Sevin'.

At about one month before harvest, 10 plants from each plot were carefully uprooted and the number of effective nodules counted. At harvest the yield of dry clean soybean seeds per plot was recorded. Results were statistically analyzed (Steel and Torrie, 1960).

At Matthews' Ridge, the experiment was first planted in November, 1969 and replanted on the same site in May and November, 1970. At Mon Repos, the experiment was planted in November, 1970.

RESULTS

Yield

The yield results are presented in Tables 2-5. At no time was the effect of N significant. Inoculum had a significant effect (P-<1 0.05) only

at the May, 1970 planting at Matthews' Ridge, where yields at the i2 level were higher than those at the i„ and i. levels. In November, 1970 planting - 152 - at Matthews Ridge the NI interaction was significant (P < 0.05). Examina- tion of this interaction showed that within the n^ level, yields at the i^ level were significantly lower than those at the ig level.

Table 2. Effect of varying levels of N and Inoculum on Soybeans Yields (kg/ha). Planted November, 1969 at Matthews' Ridge.

Inocula (g/kg seed) Nitrogen Means (kg/ha) 0 224 448

kg/ha

0 1500 1400 1882 1594

16 1706 1975 1562 1747

32 1986 1946 1768 1906

4 8 2042 1926 1966 1981

Means 1808 1814 1799

S.E.: N means = 159 I means ™ 137 I level means within the same N level =* 276 - 153 -

Table 3. Effect of varying levels of N and inoculum on soybean yields (kg/ha). Planted May, 1970, at Matthews' Ridge

Nitrogen Inocula (g/kg seed) (kg/ha) Means 0 224 448

kg/ha

0 2255 2162 2371 2263

16 2238 2277 2451 2322

32 2158 1980 2555 2231

48 1841 2288 2606 2245

Means 2123 2177 2496

S.E.: N means = 126 I means - 109 I level means within the same N level - 218

Table 4. Effect of varying levels of N and inoculum on soybean yields (kg/ha), planted November, 1970 at Matthews' Ridge.

Nitrogen Inocula (g/kg seed) (kg/ha) Means 0 224 448

kg/ha

0 3655 3812 3687 3718

16 3972 3678 3889 3846

32 3551 3573 3592 3572

48 3895 3973 3555 3741

Means 3781 3759 3631

S.E.: N means » 205 N means = 89 I levels means within the same N level - 173 - 154 -

Table 5. Effect of varying levels of N and inoculum on yields (kg/ha) of soybeans. Planted November, 1970 at Mon Repos.

Nitrogen Inocula (g/kg seed) Means (kg/ha) 0 224 448

kg /ha

0 4058 4105 4043 4068

16 4355 4135 4307 4266

32 4197 4043 4058 4098

48 4245 3723 4095 4020

Means 4212 4003 4122

S.E.: N means » 171

I means » 164

I level means within the same N level 330

Leaf colour was not markedly affected by the treatments at any of the plantings.

Nodulation

The results on nodulation for the May, 1970 Matthews' Ridge and November,

1970 Mon Repos plantings presented in Tables 6 and 7, respectively, show that the number of nodules was not affected by either N or inoculum. At the latter planting, examination of the N x I interaction which was significant (P 0.05) showed that at the NQ level, the number of nodules at the i^ level was greater than that of the check. Although actual nodule weights were not recorded, the nodules from all plots were approximately the same size and thus nodule numbers give a good assessment of treatment effects. It should be mentioned here that - 155 -

Table 6. Effect of varying levels of N and inoculum on nodules (No. plant) of soybeans. Planted May, 1970 at Matthews' Ridge.

Nitrogen Inocula (g/kg seed) (kg/ha) Means 0 224 448

Av. No./ plant

0 56 49 52 52

16 43 43 50 46

32 62 65 51 60

48 30 56 51 46

Means 48 53 51

S.E.: N means » 6.0 I means * 5.2 X level means within the same N level - 10.4

Table 7. Effect of varying levels of N and inoculum on Av. No. of nodules per plant. Planted November, 1970 at Mon Repos.

Nitrogen Inocula (g/kg seed) Means (kg/ha) 0 224 448 Av. No./ plant 0 15 24 21 20

16 29 23 16 23

32 14 18 20 17

48 19 21 20 20

Means 19 21 19

S.E.: N means *» 3.0 I means " 2.2 I level means within the same N level » 4.3 - 156 -

DISCUSSION

Generally both N and inoculum had no effect on the performance of soybeans. The purpose of applying N is supposedly to satisfy the crop's N requirements until the crop can manufacture Its own with the aid of rhizobia.

Both soils has relatively high concentrations of total N (0.2 and 0.1%).

Cornforth, (1971) has found that In soils in high rainfall areas (2300 mm per year), 70 ppm N can be mineralized at the start of the rainy season.

These soils are. both In high rainfall areas (Mon Repos, 2375 mm; Matthews'

Ridge, 2500 mm) so that it could be safely assumed that there was an adequate supply of mineral N when the soybeans were planted.

Shukla (1969) and Chesney (1969) have reported similar findings with N on soybeans in Guyana.

The failure of inoculum to generally influence yield and nodulation especially at the first plantings is very noteworthy. Iswaran, Sarma and

Comnaire (1970) in their review article stated that the rhizobial population in acid soils is generally considered to be low and that rhizobia do not per- sist in these soils. It will be safe to assume that these soils, both naturally very acid, would have very low rhizobial populations. If this assumption is correct, then it must be concluded that the commercial lnoculant used was not effective. Supporting evidence for this conclusion comes from Abel and Erdman (1964) who have stated that when soybeans was first introduced into the southwestern U.S.A. the commercial inoculants used were not effective. The general increases in yield that occurred in the subsequent plantings at Matthews' Ridge may have been caused by a build up of rhizobia in the soil because of the presence of the soybean plants; this further suggests that the inoculum used was ineffective. - L57 -

The significant effect of inoculum at the May, 1970 planting at Matthews'

Ridge is inconsistent with the other results. Caldwell and Vest (1970) have however, found that there is a significant rhizobia strain X year interaction on yields of soybeans in the U.S.A., perhaps a similar interaction or a strain

X season interaction occurs in Guyana.

The finding at the November, 1970 planting that inoculum increased nodulation only in the sence of N suggests that N may have inhibited the action of the Introduced rhizobia. However, since this effect did not always occur, plus the fact that neither of the main factors were significant, much emphasis cannot be placed on this observation.

It is seen from these studies that the question of inoculation of soybeans in Guyana is not a simple one and much work needs to be done to gain a full understanding' of the mechanisms involved. Some of this work will have to be done under greenhouse conditions where greater control can be achieved.

SUMMARY

The effect of nitrogen (N) and inoculum (Rhlzoblum laponlcum) on the yield and nodulation of soybeans (Glycine max (L.) Merrill. CV 'Jupiter') was studied on two soil types of Guyana. Generally, nodulation and yield were bogh unaffected by N and inoculum. Possible reasons for these effects are discussed.

REFERENCES

1. Abel, G.H. and Erdman, L.W. 1964. Response of Lee soybeans to different strains of Rhlzoblum laponlcum. Agron. J. 56: 423-424.

2. Caldwell, B.E. and Vest, G. 1970. Effects of Rhlzoblum laponlcum strains on soybean yields. Crop Sci. 10: 19-21. - 158 -

3. Chesney, H.A.D. 1969. The effect of fertilizer nitrogen, phosphorus and potassium on yield of soybean (Glycine max (L.) Merrill) on Arakaka clay loam, Guyana. Agric. Res. Guyana 3: 105-107.

4. Jacob, A. and Uexkiill, von H. 1963. Nutrition and Manuring of Tropical Crops. Fertilizer Use, pp 191 - 194. 3rd. Ed. Verlagsgesellechaft fitt Ackerban, Hanover.

5. Isvaran, V. , Sarma, K.S.B. and Comhaire, H. 1970. Soil fertility, legumes and rhizobium efficiency. I. Introduction, effect of organic matter and soil reaction. AGRI Digest 19: 3-19.

6. Ramdin, H. 1969. Soil Survey Report of the Baraima-tKaituma-Arakaka areas. Unpubl. Library, C.A.S. Min. of Agric. Guyana.

7. Ramdin, H. 1966. Soil Survey Report of the Central Agricultural Station, Mon Repos, Guyana. Unpubl. Library, C.A.S. Min. Agric. Guyana.

8. Shukla, G.C. 1966. Fertilizer trials with soybeans. Agric. Res. Guyana. 3: 99-104.

9. Steel, R.G.D. and Torrie, J.R. 1960. Principles and Procedures of Statistics. Mc Graw-Hill Book Co., Inc., N.Y. - 159 -

The Pattern of Crop Production in Guyana

R.E. Fletcher^

The pattern of crop production that obtains in Guyana today can be directly related to three factors:-

1. The social and economic history of the country;

2. The geophysical nature of the country;

3. The pattern of distribution of the various soil groups.

The majority of the Guyanese population inhabit the flat low-lying coastal strip that extends across the width of the country and occupies just about 10% of the total land area. It is significant that, in addition to being the only area of coastline possessed by the country, these soils collectively are considered to be agriculturally superior to most of the other large soil groups that have been classified. Crop production therefore, is virtually a coastal occupation.

Little incentive is available to farmers who wish to move off the coastland due to poor communications and a paucity of information and techniques on the cultivation and management of soils lying behind the pegasse swamps that delimit coastal and hinterland areas. The need for crop diversification in a country whose economy relies on agriculture is now being forcibly realised. The area of the country in which diversification will create the greatest impact is on the virtually unpopulated hinterland behind the coast.

It is therefore convenient to treat this discussion under two sections:-

(a) Coastal Agriculture - dealing with production of mainly

traditional crops on established coastal areas.

Agronomist, Ministry of Agriculture, Guyana. - 160 -

(b) Interior or hinterland agriculture - involving attempts

being made to bring areas behind the coast under cultivation.

Coastal Agriculture: The flat low-lying heavy clays of the coastal area of Guyana,

although generally fertile, require an intensive system of drainage before being

brought under cultivation. These soils support sugar and rice which constitute

the backbone of the agricultural economy of the country. Coconuts is next in

importance. Fruits, food crops and vegetables are grown widely on a peasant scale.

Sugar: The sugar industry is dominated by two large companies with an efficient

and well organized system of production. Lands under sugar are restricted mainly

to the Demerara and Berbice sections of the coastal area and have been under sugar

in some cases for several decades. The system of drainage and irrigation canals

and the method of water transport of the harvested cane from the fields are pecu- liar to Guyana.

Of considerable significance is the recent introduction into the industry of

the "small cane-farmer" - individual growers who with the help and guidance of the

National Cane Farming Association, produce cane which is sold to the factories and milled by the estates. The gradual increase both in numbers and in output of these farmers is an indication of the lucrative nature of this occupation. The present contribution of about 25,000 tons of sugar (1969 figure) from this source is about

7% of the national output.

In several instances lands under permanent or semipermanent crops is being brought under sugar because of the relative case of cultivation and the ready market available. Harvesting poses the usual problems.

Rice: The rice industry in Guyana has evolved from a small scale peasant operation based on family labour to a viable operation involving several farmers of variable

status, and a huge national infracture with a potential of further streamlining

the industry. - 161 -

Soils on the coast are on the whole well suited to large scale production, however the attitude of this area (6 ft. below sea level) and heavy rains experienced at certain periods during the year generally pose problems of flooding and water control.

Size of rice fields varies from fractions of an acre still cultivated in the traditional peasant fashion, to several hundred acres of highly mechanised cultivation. Certain land Settlement schemes e.g. Black Bush Polder in the Corentyife and Anna Regina and Tapakuma in the county of Essequibo are devoted mainly to the cultivation of rice on holdings ranging from 5 to 20 acres. The Mahaica/Mahaicony/

Abary area is considered the mecca of rice production and it is in this area that research facilities are to be centered.

The formation of the Rice Development Corporation can be considered the first major 3tep toward streamlining of the industry. This organization is expected to be responsible for all aspects of the industry - production marketing and research.

The primary objective is increasing the average yield per acre by the use of improved varieties and by improvement of cultural practices.

Coconuts: The estimated acreage under coconuts at the end of 1969 was 46,000 acres comprising estates and numerous scattered plantings in villages and along dams of drainage and irrigation canals. The free draining nature of the sand reef soils along the coast makes those soils ideal for coconuts and it is here that the best crops are seen.

There does not seem to be any significant expansion of cultivated area under coconuts. General neglect of estates and poor harvesting techniques may be responsible for decline in oil production in recent years. The increasing importance of the water-coconut industry is also a contributary factor. - 162 -

The Ministry of Agriculture is: responsible for the production of seeding nuts

for sale distribution to farmers. Dwarf coconut seedlings are also now being pro-

duced to cater for the water coconut industry.

Research into the two major pests - Red ring disease and the Palm Weeoil are

being done by the research staff of the Ministry of Agriculture.

Citrus: Citrus production is concentrated in the North West District and the Po-

meroon and Canals polder areas. Generally the riverain soils and the rolling soils

of the North West District are suited to this crop. The cultivated acreage is esti-

mated at 5,000 acres with the largest and most productive estates in the North West

District. Small growers however, account for the majority of the annual production

of 20 million pounds of fruit - mainly oranges - to satisfy the local fresh fruit

market and a small canning industry.

The variety most widely cultivated is Valencia, however several other types

are distributed by the Ministry of Agriculture to farmers. These include Parson

Brown, Washington Navel, Ruby and Pineapple. The Marsh variety of Grapefruit and

West Indian limes are also grown on some scale. In the North West District a lime- oil industry has been initiated by one of the large producers.

On the coast, we heavy soils have contributed to rapid decline of bearing trees.

Root stock testing is in progress for compatibility between stock and scion with

regard ti resistance to virus diseases,

Pineapples: This crop is becoming increasingly important. Traditionally, pineapples are grown in the Canals Polder area on lands immediately behind the coastal area and on other free draining sandy soils on the coast. The predominant variety is

Montserrat.

The acreage under cultivation still remains small (about 400 acres) however the recent construction of the Timehri/Linden highway has made accesible several thousands - 163 - of acres of White and Brown sand soils which are well suited to pineapple cultivation with moderate fertilization.

Other orchard Crops: Cocoa production satisfies only a small market. There has been no significant increase in acreage over the past few years.

Coffee is grown in the hilly North West District and in the Pomeroon. The crop is of little significance on the flat coastal area. The variety cultivated is Liberies which yields well under prevailing environmental conditions and i3 also tolerant to poor management practices.

Production of other fruits - mangoes, avocados, bananas etc. is geared toward providing for the local market. These are grown on the typical small mixed farm and are seasonal in production.

Grapes: With the implementation of restrictions on the importation of grapes into the country efforts are being made to encourage production of local varieties of this fruit. These varieties have been collected from individual growers and pro- pogated by cuttings. A plant distribution programme has been arranged by the Minis- try of Agriculture and this is concentrated in the first instance, on homesteads in and around Georgetown. A team of trained technicians i3 available to service and advice on cultural practices for vines planted at various locations.

Food Crops: With the exception of rice, food crops grown for local consumption and for the export market are produced on small cultivations by individual farmers.

Collectively this amounts to large quantities especially of plantains and ground provisions which are marketed in the urban areas. Table 1 shows production figures of some of the more important items of food crops for 1969. - 164 -

Table 1 - Acreages and annual production of important food crops (.1969).

ACREAGE UNDER CROP CULTIVATION PRODUCTION (LBS.)

Plantains 14320 48860900

Bananas 2940 12684700

Corn 2598 3900000

Black Eye Peas 348 279600

Peanuts 60 63800

Cabbages 148 698700

Tomatoes 798 3412900

A system of shifting cultivation or land fallowing is generally practiced in

certain areas for cultivation of food crops. Virgin lands generally give good yields and as the soil fertility is depleted the crop is shifted to a> new area.

Hinterland Agriculture: Within the virtually undeveloped hinterland of Guyana lies

a vast potential for agricultural development. Exploitation of this potential has been hiterto restricted by difficulty of communication and sparseness of the inte-

rior population.

The Intermediate Savannahs: This area of white and brown sands which is low to

extremely low in natural fertility possessed probably the greatest exploitable potential for large 3cale production of food crops. Crop research has been in progress on these soils for the past eight years and data has indicated that legumi- nous crops - Soybeans and Peanuts are well suited to the area.

The major limiting factor to cultivation of this area is fertility. Drainage problems as encountered on the coast are insignificant or non existent on these - 165 - free draining soils with rolling topography. The predominant grass vegetation can be easily cleared, and taking in of virgin land for cultivation is an extremely cheap operation.

In 1970 the Kibilibiri project was initiated in the savannahs. This project involves the cultivation of about 1,500 acres to hybrid Corn, Soybeans, Sorghum and

Peanuts. Heavy fertilization is required initially, however it is expected that yields would improve with continuous cropping due to increase in levels of Organic

Matter: Phosphorus and Trace Elements in previously cropped soil.

The Intermediate Savannahs also hold promise as a major beef producing area.

The Beef Research Unit at the Ebini Research Station established since the early

1949s is engaged in a study of the response of beef herds to grazing on rangs and on range and on improved pastures. Several hundreds of acres of improved pastures have already been established at Ebini.

The Rupununi Savannahs: This is another area of poor sandy soils and savannah type vegetation. Cattle ranching is the main occupation, however excellent crops of vegetables (Tomatoes and cabbages) have been produced on the deep rich soils of the mountain valleys. Due to the rainfall pattern in this area where flooding of the savannahs occurs during the long rainy season, most food crops are grown during the dry periods of the year. Crops grown in these relatively inaccessible areas necessarily have to be air freighted to markets in Georgetown.

The Worth West District: This area has been briefly mentioned in the first section of the paper. Most of the area constitutes heavily forested hills and swamps. The soils are of good texture and generally of medium to low fertility.

The North West District has the potential of becoming a large producer of citrus and avocado. Presently, some of the best crops pf avocados originate from - 166 -

this area. Efforts to encourage movement of inhabitants into the interior are re-

flected in the two land settlement schemes - Wauna Yarakita and Matthews Ridge/

Kaituma/Arakaka. Some food crops are cultivated mainly for local use. The empha-

sis however, will be on permanent tree crops which are well adapted. A programme

involving large acreages of corn and peanuts is now being implemented at Matthews

Ridge - an area that was formerly involved in Manganese Production.

Other areas: Several thousand square miles of virgin rain forest exist in southern and central areas of the country. For the most part soils in these areas are derived from sandstone material resulting in acid soils of low fertility. However pockets of deep rich soil occur in mountain valleys and along river courses. Good crops of high priced vegetables have been produced on some of these areas but problems of marketing and reliable communication have been encountered.

Conclusion: It is clear that the crop diversification programme vital as it is to the country's economy must necessarily be synonymous with interior development.

Improved communications and a greater incentive to leave the coastlands are a vital necessity.

There still exists a great deal of scope for further development of crops on the coastal clay soils. However the incentive of good reliable markets and keeping the farmers well informed on production and handling techniques is necessary for further significant development. - 167 -

SOME RECENT STUDIES ON RICE PESTS IN GUYANA

B.K. Rai—^

INTRODUCTION

Rice is the dominant crop grovn on the flat coastal lands and is the second most important economic crop after sugarcane. In the spring and autumn seasons about 30,000 and 80,000 ha. are cultivated, annually. With emphasis on new plant type, heavier fertilization and multiple cropping which lead to greater production per unit area and time; pest incidence is increasing and is bound to increase further, as is happening in other parts of the world (Pradhan, 1969). However, if problems are recognized soon enough, they could be solved by careful research and planning; since pest control technology is in a healthy situation to confront the new demands of changed/improved agriculture. Studies on incidence of pests, more effective and less costly insecticides and quick application of insecticides; have been in progress at the Central Agricultural Station and some of the results obtained are presented in this paper.

A. A TECHNIQUE FOR LOW-VOLUME DRIFT SPRAYING OF PADDIES

The term drift spraying denotes a method of applying insecticidal spray whereby it is released at a height above the crop to be treated and cross winds carry and distribute the spray droplets on to the vegetation, downwind. This method has been successfully used for the control of locusts in Africa (Courshee,

1959). Normally the wind velocity on the coastland of Guyana, ranges between 10 to 15 km./hr. from 8.00 a.m. to 6.00 p.m. (Cleare, 1961). In view of this it was decided to resort to drift spraying of paddies to cut down the time required for spraying of insecticides.

— Central Agricultural Station, Hon Repos, Guyana, South America. - 168 -

The spraying equipment popular in Guyana, is a motorized knapsack or

back pack sprayer (70 c.c.). It has four adjustments for getting different flow

rates of insecticides. One low-volume attachment), comprising of a drilled metal-

lic plate with a strainer, available commercially, was used to get still lower

flow rates of insecticides. This attachment is mounted in the flow line of

insecticide.

The drift of insecticidal sprays treated, up to two months old paddies, at least to a distance of 9 metres when the outlet of insecticide was kept along 3 the wind and about - 1 metre above the ground. When wind velocity was high 3 (15 km./hr.), the spray outlet was kept about ^r metre above the ground while when wind velocity was low (10 km./hr.), the spray outlet was kept about one metre above the ground. When wind velocity approached or exceeded 20 km./hr., spraying was not carried out. Rice caterpillar, Spodoptera frugiperda S. & A., dipterous stem maggot, Hydrellia sp. n., nr. spihicornis Cresson, jassids and fulgorids (under identification) generally attack when plants are up to two months old.

The drift of insecticidal sprays treated, more than two month old or flowering crop, at least up to 6m. when the outlet of insecticide was kept along the wind and 15 to 30 cm. above the crop. When wind velocity was high (15 km./hr.), the spray outlet was kept about 15 cm. above the crop while when wind velocity was low (10 km./hr.), the spray outlet was kept, 30 cm. above the crop. When wind velocity was very much higher, spraying was not done. Long horned grass hoppers,

Heoconocephalus sp. and Caulopsis cuspidata Scudder attack starts late in season and continues along with paddy bug, Oebalus poecila (Dallas) in the flowering crop.

Drift spraying of a field is started from leeward side and the person spraying moves across the wind. Motor is kept at maximum acceleration. Insecti-

cide is released along the wind. Havingvreached the other end of the field, - 169 - person moves windward 6 metres (12 steps) or 9 metres (18 steps) depending upon the stage of crop and again starts moving across the wind and releasing insecticide along the wind (Fig. 1).

Information on control of various pests of paddy by drift spraying is presented in Table 1. By drift spraying, one tankful of insecticidal spray (II litres) can treat from about 0.25 to 3.0 ha. and it takes about 21 to 60 minutes to treat an hectare, depending upon the pest to be controlled. According to the

United States Department of Agriculture, less than 5.5 litres of spray per ha. is considered ultra low-volume (Lofgren, 1970).

B. CAUSES OF WHITE HEAD OR PADDY

Erect, empty and white heads of paddy are generally associated with stem borer attack but quite often it was not found to be so. White heads of paddy along with stem, were collected from at least eight places in2 each of the four rice areas in Guyana. Also, number of white heads per 1.5 m in the randomly selected observation fields was recorded. The stems bearing white heads were split open and the following causes were assigned (Table II):

Table II. Causes of white head of paddy

Percent white heads due to, in Causes Spring, 1969 Autumn, 1969

Stem borer 36.1 26,8

'Break in stem' 52,5 16,6

External Injury 2,9 12,0

No. of white heads studied 1,560 1,661

E.G. 79 and DUO were the pre-dominant varieties. No obvious cause could be assigned to a certain percentage of white heads. - 170 -

Stem borer3; If the stem had an alive or dead stage of the stem borer, or even

an empty borer gallery, the white head was considered to have been caused by

stem borer, of which two species i.e., Rupella albinella Cram, and Diatraea

saccharalis F. (Pyralidae. Lepidoptera) were known. D. saccharalis was found to

be heavily parasitized by Amazon fly, Metagonistylum minense Tns. (Larvaevoridae:

Diptera). In the spring and autumn crop of 1969, borers were responsible for about 7.6% of the white heads observed.

'Break in stem': If the stem with a white head was found to have internal local-

ized shearing of internal tissues, the white head was considered to be due to

'break in stem.' Generally localized rotting and shearing was observed above the

2nd or 3rd internode from the base of the plant. An organism resembling,

Zanthomonas oryzae was repeatedly isolated but the reinoculation tests were negative.

In a replicated field experiment, the two treatments were: (i) application of insecticides after every 10 days to control insects and (ii) no application of insecticides. At the time of harvest, the white heads from each plot (plot size was 0.013 ha) were collected and analyzed. The data are presented in Table III.

In the treated plots, only 19 white heads were caused by borers against 71 in untreated plots. Break in stem was responsible for 115 white heads in treated plots against 120 white heads in untreated plots. This observation indicates that insects may not be involved in causation of the 'break in stem'. Table III. Data on white heads of paddy

No. of White No. of white heads due to heads observed Replication Stem 'Breat in External border stem' injury

Untreated plots X I 83 36 30 11

II 84 21 53 9

III 57 14 * 37 6

Total 224 71 120 26

Treated piot s

I 62 3 36 16

II 66 1 50 15

III 45 15 29 5

Total 173 19 115 36

In an individual case, 'break in stem' caused 71% white heads, but on an average, it caused 52.5 and 16.6% white heads in spring and autumn crop respectively (Table II).

External Injury: Rats and long-horned grasshoppers were observed to feed on side of the stem which resulted in white head. External injury to stem was not a major cause in spring 1969 but in Autumn, 1969, it was responsible for 12% of white heads since an outbreak of long-horned grasshoppers, Neoconocephalus sp. and Caulopsis cuspidata Scudder (Tettigonidae: Orthoptera) had occurred.

18.4 and 44.5% of white heads in spring and autumn crops respectively could not be assigned any of the above causes. - 172 -

The number of white heads varied from almost nil tc 65,000 per hectare. Very

large number of white heads were observed in some fields fertilized with nitroge-

nous fertilizers and the causes were 'break in stem' and stem borers.

C. INCIDENCE OF STEM BORER AND 'BREAK IN STEM' IN NEW VARIETIES

During the spring crop of 1971, new varieties like Star Bonnet and Hybrids

bred at Mon Repos, were cultivated by the farmers. In the month of March, 1971, a

survey was carried out to assess the incidence of stem borer and 'break in stem'

in these varieties vis-a-vis that in B.G. 79, a local variety.

Fifteen plants from each field surveyed, were uprooted; number of tillers counted; stoma were split open to find the incidence of stem borer or 'break in

stem*. The data obtained are presented in Table IV which indicated that;

(i} Incidence of borer was maximum in Star Bonnet, i.e., to the extent of 33.52 against 6,2% in the presently cultivated variety B,G. 79. The hybrid R

had borer incidence percentage 14.6 which was also more than B.G, 79 while the

other three hybrids had borer incidence percentage between 3.9 to 9.4 against

6,2 of B.G, 79.

Cii) In all the varieties, a great percentage of borer incidences was

in apparently healthy tillers. In such tillers, most probably, borer incidence started so late that white heads did not appear.

(iii) B.G. 79 is most susceptible to 'break in stem' to the extent of

3,7% against 0.0% and 0,4% in Hybrid S and Star Bonnet respectively. Causes of white head also indicate that Star Bonnet and Hybrid S were comparatively more resistant to 'break in stem'. However, the incidence of 'break in stem' is of

low order i.e., 0 to 3,7% to 33.5% of borer, when data of all varieties are taken

together.

The young paddy plants of all the new high yielding varieties were ob-

served to be infested with larvas of a dipterous borer, Hydrellla sp. n. nr. - 173 -

3pinicorni9 Cresson. Under certain conditions as yet undetermined, this pest assumed serious proportions. The varieties with higher tillering rates have a better chance of withstanding this and other pests which appear in early stages of the growth of the paddy plant. The average number of tillers per plant was

6,3 to 7.5 for hybrids, 4.7 for B,G. 79 and 3.3 for Star Bonnet.

D, TECHNIQUE FOR DETECTION OF BUG DAMAGED PADDY GRAINS

The Stink bug, Oebalus poecila (Dallas) damaged paddy grains, produce discoloured rice. Without a suitable, quick test for determining the extent of damaged paddy, the producers cannot know the quality of their produce and the buyers cannot know the quality of their buy,

A large number or methods were tried and the under-mentioned method was found to be quite good, Paddy sample (30 gm.) was inmer3ed in 10% sodium hydroxide solution (100 ml.) at 70c° and was allowed to remain in that solution for 10 -15 minutes at 70c*, by regulated heat. Paddy varieties like Star Bonnet, B.G. 79 and

D 110 which had lightly pigmented coat, required about 10 minutes of heating while a variety like Blue Belle which had a heavily pigmented coat, required about 15 minutes of heating, to show up the bug damaged spots. After heating, paddy was washed two to three time in water and was spread in a white enamel tray, under a film of water, Bug damaged grains showed round target spots. Ready reckoning tables for working out percent damaged paddy from number of damaged grains observed in a fixed weight of sample could he made separately for varieties with different average weights per grain.

Fifteen samples of paddy, having bug damaged grains ranging between 0,5 to 14% as revealed by the method described above, were processed to get parboilded rice. Percentage by weight of discoloured grains fue to bug damage in parboiled rice was worked out by visually separating the discoloured grains. The results of - 174 -

percentage damaged grains as obtained by treating the paddy with Na OH and by parboiling, compared favourably.

Wilbur et^ al. (1970) obtained good contrast between bug damaged and undamaged grains by heating dehusked paddy to 54c*in 0.03 - 1.5 N hydrochloric acid for 1 minute. Since paddy requires to be dehusked before this technique could be used, the Na OH method as described earlier is considered better.

E. INCIDENCE OF PADDY BUG

The paddy bug causes both quantitative and qualitative losses by sucking the developing grains and leaving target spots on the paddy which lead to production of dis-coloured rice. An estimate of qualitative loss is expected to indicate the bug incidence.

Rice farmers bring their paddy for sale to rice mills, invariably soon after harvest. Samples of paddy were drawn from various lots of paddy that came for sale at a big rice mill, each at East Coast, Demerara and Essequibo. 30 gm. paddy from each sample was analyzed for percentage of bug damaged grains by the technique described earlier,

The data on extent of quality loss of paddy for Autumn, 1969 presented in Table V indicate that;

(i) 24.7, 39,0 and 63,52 samples of paddy (all varieties together) harvested in early, mid and late autumn season respectively, had more than 0.52 bug damaged grains. The greater incidence of bug damaged paddy in later harvests, suggest that the bugs migrate from harvested fields to ripening one3. The situation would become serious for fields maturing late in season when almost all other

fields were harvested. The applied significance of this observation is that the cultivators whose paddies are in milk, or dough stage when their neighbours are harvesting, should be more careful about the bug incidence in their paddies. - 175 -

(ii) Mixed varieties of paddy had higher incidence of hug damaged grains

than the pure varieties, irrespective of the time of harvest. It could be due to

prolonged availability of susceptible stage in field since different varieties may star flowering at different times.

The data on extent of quality loss of paddy for Autumn, 1969, Spring,

1970 and Autumn, 1970 are presented in Table VI;

Table VI, Paddy bug damage incidence

Percent bug Percent of sample damaged grains Autumn, 1969 Spring, 1970 Autumn, 1970

0,0 92,1 93.8 89.0 0.5 43.0 71.0 40.6 1,0 17,7 50.5 17.9 1.5 6.6 38.0 6.9

2,0 3,0 32.5 2.4 2.5 1.5 26,5 0.0 3,0 0,6 20.5 4,0 0,3 15.3

5.0 0.0 9.3 10.0 2.3 18.0 0.8 25.0 0.4

35.0 0.2 50.0 0.0

Total no. of samples analyzed 332 483 246

Which indicate that about 40% of samples of paddy in autumn crops of 1969 and 1970 and 71% of samples in spring, 1970; had more than 0.5% bug damaged grains and thus got less money than they would have got otherwise. According to the grading system in vogue, at more than 0.5% damaged paddy, the price paid is reduced. - 176 -

About 80,000 and 30,000 ha. of rite are cultivated in Autumn and Spring crop respectively. In view of Che above results about 32,000 and 21,000 ha. will require to be treated for bug control, during the Autumn and Spring crop respectively, each year. The cost of insecticide alone, to treat this area works out to G$300,000,00 per year. The immensity of paddy bug menace is obvious.

F. PROCESSING OF PADDY TO REDUCE BUG DAMAGED GRAINS

White rice: Fifteen samples of paddy, having bug damaged grains ranging between 0,5 to 14%, were processed to obtain unpolished white and parboiled rice.

The data presented in Pig. II indicate that white rice shows about 2/3 as much discoloured grains as parboiled rice.

Further, a sample of paddy with 9.9Z bug damaged grains, showed 6 and 2Z bug damaged grains in unpolished and polished white rice respectively.

Three subsamples of 50 gm. each of polished white rice, were separated into brokens and whole grains and were analyzed for bug damaged grains. On an average whole grains and brokens contained 0.17 and 17.1Z bug damaged grains respectively. Thus it is evident that most of the bug damaged grains pass into the brokens,

Since white rice shows less bug damaged grains than the parboiled rice; undamaged whole and broken grains of polished white rice were boiled to see if the signs of damage appeared after boiling. The results were negative.

These datas clearly show that it is possible to get a very good quality of white rice from bug damaged paddy.

Parboiled rice; Paddy bug damaged grains are generally lighter than the normal ones, It was observed that if paddy was dropped in water and the floating grains were immediately skimmed off, then the settled paddy was comparatively free of bug damaged, unripe and shrivelled grains and a better grads of parboiled rice was obtained. - 177 -

Three samples of paddy variety DUO were skimmed in water and 20%

common - salt solution. Data presented in Table VII show that when grains

floating over water were immediately removed, the percentage of bug damaged

grains dropped to 0,9 from 1,3 and 1.7 in the unskimmed paddy.

Table VII. Skimming of paddy to remove bug damaged grains

% skimmings (Wt,) %discoloured grains Variety Water 20% Whole Settled paddy salt paddy Water 20% salt

D 110 7.5 11.0 1.7 0.9 0.2 D 110 5.6 14.7 1.7 0.9 0.2 D 110 5.3 11.4 1.3 0.9 0.1

When grains floating over 20% common-salt solution were removed, the

settled paddy had 0.1 - 0.2% damaged grains against 1.3 - 1.7% in the unskimmed

paddy.

During the parboiling process, paddy is soaked in hot or cold water.

If floating paddy is not immediately removed then lighter floating grains compris-

ing of unripe, shrivelled and bug damaged grains, obsorb water, become heavier and settle down. In order to produce a better grade of rice, the floating grains

should be immediately removed on soaking of paddy in water.

Guyana Rice Marketing Board, has a series of electronic separators,

through which final product is passed and the discoloured grains get separated

from both white and parboiled rice.

G. CONTROL OF PADDY MOTH, Sitotroga cerealella (Olive)

Paddy is stored in bags, in naturally ventilated bonds. A preliminary

survey of paddy bonds carried out in 1970 indicated that paddy moth, Sitotroga - 178 - cerealella (Olive.), was the major pest followed by Rhizopertha dominica (Fab.) and Tribolium castaneum (Herbst.). These findings are similar to those reported by Cleare (1962).

To control the infestation of paddy moth, phostoxin and methyl bromide fumigation has been recommended but most of the bonds in Guyana are such that fumigation is not possible. Since, moths come out of the bags, mate and lay eggs; it is logical that a persistent, quick knook-down insecticide applied to bags, should control the moth infestation.

MATERIALS AND METHODS

Technical grades of insecticides of low mammalian toxicity, were formulated as emulsions in the laboratory. Further, commercial wettable powders of iodfenphos and carbaryl were also used. 2 ml, of insecticide fluid was sprayed from Potter's spray tower on each of the two sides of pieces of jute sackings.

The spray was allowed to dry. At 0.01% concentration, the deposit of a.e. was

2.4 ugm./cm2. One piece of jute sacking was placed in a petri dish and then the petri dish was covered with another piece of jute sacking. Bond collected adult cerealella, Rhizopertha dominica and Tribolium castaneum, were enclosed in between the sacking for 24 hours, after which mortality observations were recorded, There were four replications of 10 - 15 insects each for each treatment.

Insects were exposed to insecticidal residues at different intervals.

For working out the time taken by moths to get knocked down on exposure to residues of insecticides, petri dishes were sprayed with insecticides under

Potter's spray tower. Spray was allowed to dry and then 10 - 12 moths were enclosed in each pair of dish. There were three replications for each treatment. The petri dishes were observed continuosly and time for knock down of 1st, 2nd, 3rd,.,.. - 179 - moth was recorded. Log. time for knock down was plotted against probit knock down and time required for knock down of 501 moths (Kd. t. 50) was worked out.

Commercial 50% phoxim E.C, (Baythion) was used for trials in bonds.

Motorized knapsack sprayer (70 cc.) was used for spraying the bonds.

RESULTS AND DISCUSSION

Laboratory tests; Nine insecticides tested for their duration of effectiveness on jate sacking against the adult S. cerealella indicated (Table

III) that phoxim, pirimiphos methyl, iodfenphos and lindans were effective for longer duration than the others. Kd,t. 60 for phoxim, pirimiphos methyl, iodfenphos and lindane were 18, 39, 112 and 118 minutes respectively at 0,1% concentration and 21, 39, 166 and 159 minutes respectively at 0.05% concentration. - 180 -

Table VIII. Corrected percent kill of adult S. cerealella, exposed to insecticides on jute sacking

Age of residues in days Treatment 3 15 30 60 90

Phoxim* 0.1% 100 100 100 97 97 Phoxim 0.05% 100 100 100 95 89 Pirimiphos methyl 0.1% 100 100 100 100 91 Pirimiphos methyl 0.05% 100 100 98 92 77

Iodfenphos 0.1% 98 100 100 86 89 Iodfenphos 0,05% 100 96 91 73 87 Iodfenphos suspension 0,1% 100 98 100 92 75 Iodfenphos suspension 0,05% 100 84 85 73 70

Lindane 0.1% 100 100 100 98 84 Lindane 0.05% 100 100 97 96 83 Tetrachlorvinphos 0.1% 100 100 100 68 40 Tetrachlorvinphos 0.05% 100 100 100 75 55

Fenitrothion 0,1% 98 23 0 Fenitrothion 0.05% 84 17 0 Trichlorphon 0.1% 100 52 0 Trichlorphon 0.05% 100 27 0

Malathion 0,1% 25 Malathion 0,05% 20 Carbaryl suspension 0.1% 13 Carbaryl suspension 0.05% 10

A maximum of 14% mortality in control was observed.

Thus phoxim and pirimphos methyl knocked down the moths much faster than iodfenphos or lindane. In view of these results and that the acute oral LD. 50 - 181 -

to rats of phoxim and pirimiphos methyl ia more than 1,000 mg./kg, (Mc, Donald

and Gillenwater, 1967) and 2,050 mg./kg. (Anon., 1970a) respectively against

1,375 mg./kg. of malathion (Gaines, 1960), these two insecticides are of poten-

tial importance in control of the paddy moth.

Control of infestation: Since large quantities of phoxim 50% E.C.

(Baythion) were available, three bonds heavily infested with the paddy moth were sprayed with phoxim 0.25%, using a motorized knapsack sprayer. The air

blast speed of the sprayer was kept low so that droplets of spray directly set-

tled over the bags. The stacks of paddy were sprayed with phoxim emulsion2 . The deposit of insecticide on bags worked out to 150 mgm. a.i./metre of stack

surface. Within twenty minutes of spraying, almost all moths in the bonds were

killed. The data on the pre-and post-treatmen population of the moths (average

of 20 spot observations) of one bond are Riven below: -

Pre-trcatment population

2.5 moths per 0,3 m^ of stack surface

Post-treatment population

5 days - 0,2 moths/0,3 m^ of stack surface

9 days - 0,0 do 14 days - 0,1 do 22 days - 0.1 do 29 days - 0.0 do 32 days - 0.0 do 39 days - 0.1 do 44 days - 0.0 do 51 days - 0.0 do

On the 14th day after treatment, some bags were found open and they had

some moths sitting on loose paddy. These bags were sewn and sprayed. Basically

similar results were obtained in the other two bonds. It took about 45 minutes

to treat a bond properly stacked and containing about 25,000 bags. - 182 -

Prevention of infestation: Infestation by the moth could be com-

pletely prevented (up to six months) by applying phoxim 0.25% emulsion spray

on to the bagged paddy, either as each layer of bags is laid or after the

stacks are completed (Table IX).

Table IX. Prevention of infestation of paddy with cerealella Phoxim 0.25% a.i. spray applied with motoblo on to the bags

I Bond No. 1 Bond No. 2 Bond No. 3 i Bags treated Completed Stacks not 1 layer by stacks treated i layer sprayed control

1. Date stacks laid/treated 24/9/70 to 23/10/70 to October 19/12/70 11/11/70 1970

2. gm. a.i. used 5,300 505 - 3. No. of bags of paddy in hand. 94,021 61,870 Not calculated

4. No. of moths observed Nil, till Nil, till 23/11/70 May, 1971 April, 1971 3.6/0.3 m2 when paddy of stack was milled surface out. 27/11/70 ,, 6.5/0.3 n' of stack surface. 15/12/70 48.2.0.3 m2 of stick surface. 26/12/70 to May, 1971 Moths uncoun- table.

5. One litre of 50Z E.C. 9,000 bags 60,000 bags - treated 564 tons. or 3,800 tons

6. Insecticide worth 470 bags 3,270 bags GS 1.00 treated or 3 tons. or 209 tons. - 183 -

Data presented in Table X show that percentage of grains damaged by insects is much more in the bond where cerealella was not controlled than in those where it was controlled.

Table X. Extent of damage to bagged paddy in storage by Sitotroga cerealella and other pests.

Observations recorded 5th month after storage in 3 different bonds.

No. of insects recorded in Site of % grain (4 x 500 g. paddy) Treatment stack bored sampled R.d. T.c. S.c. C.f. L.p. Preda- sp. tory bug

1. Sitotroga cerealella Side 1.37 253 33 0 17 0 5 controlled Middle .43 208 2 0 43 3 1 Top .81 4942 10 0 9 0 0

2. Sitotroga cerealella Side 2.00 3466 48 0 25 5 67 controlled Middle 0.50 326 14 2 27 0 6 Top 0.31 507 5 0 16 0 3

3. Infested with Side 11.60 435 13 3 258 I 10 Sitotroga cerealella Middle 3.80 442 33 0 29 5 0 Top 16.37 677 1 0 244 0 46

R.d. - Rhizopertha dominica (F.) C.F. - Cryptolestes sp. T.c. - Tribolium castaneum (Hbst.) L.p. - Lophocateres pusillus (Klug) S.c. - Sitophilus oryzas L.)

Residues on jute of phoxim and pirimiphos methyl are quite toxic to

Rhizopertha dominica (Table XI) while pirimiphos methyl is quite toxic to

Tribolium castaneum (Table XII). - 184 -

Table XI. Corrected percent kill of adult Rhizopertha dominica, exposed to residues of insecticides on jute sacking.

Rhizopertha dominica

Age of residues in days Treatment 7 15 30 60 90

Phoxim 0.1% 100 93 92 77 43

Phoxim 0.05% 79 80 79 33 15

Pirimiphos methyl 0. 1% 73 45 56 55 24

Pirimiphos methyl 0.05% 30 23 20 17 21

Iodfenphos 0.1% 45 62 - 50 31

Iodfenphos o.05% 39 36 - 34 17

Fenitrothion 0.1% 32 80 54 50 7

Fenitrothion 0.05% 76 80 43 33 2

Malathion 0.1% 73 88 56 41 30

Malathion 0.05% 66 73 30 34 7

Lindane 0.1% 55 65 0

Lindane 0.05% 52 33 0

Tetrachlorviphos 0.1% 48 40 0

Tetrachlorviphos 0.05% 39 50 0

Carbaryl 0.1% 76 53 0

Carbaryl 0.05% 42 35 0

Trichlorphon 0.1% 33 18 0

Trichlorphon 0.05% 30 10 0 t

A maximum of 15% mortality in control was observed. - 185 -

Table XII. Corrected percent kill of Tribollum castansum, exposed to residues of insectides on jute sacking.

Age of residues in days Treatment 3 10 30 60 90

Pirimiphos methyl 0.1% 100 80 75 56 21

Pirimiphos methyl 0.05% 33 30 10 7 0

Phoxim 0.1% 34 28 0

Phoxim 0.05% 13 0 0

Three days old residues of 0.1 and 0.05% lindane, iodfenphos, tetrachlorvinphos, malathion, carbaryl, trichlorphon and fenitrothion gave less than ten percent kill. The percentage mortality in control varied from 0 to 5 percent.

These pests when crawled out on to the treated jute surface, got killed.

However, they continued to breed inside the bag as is evident from Tahle X,

The amount of insecticide used for the control of S. cerealella depends upon the size of stacks. In the present studies, some of the stacks were as big as 60m x 6m x 7m, while an average size was 18m x 13m x 7m, C>ne litre of 50% E.C. treated about 60,000 bags or 3,800 ton of paddy when bags were sprayed after stacking adn G$1.00 worth of insecticide treated about 3,270 bags or 209 tons of paddy when stacked bags were sprayed (Table IX).

SUMMARY

The natural wind velocity of 10 - 15 km./hr. was used to cut down time of spraying of paddies; by resorting to drift spraying, using a motorized knapsack sprayer. - 136 -

The incidence of stem borers, 'break in stem' (internal localized rotting and external injuring to stem caused by rats/long-horned grasshoppers; resulted in erect, empty and white heads of paddy. Relative incidence of stem borers and 'break in stem' in some of the rice varieties is reported.

A technique for detection of bug (Oebalus poecila (Dallas)) damaged grains in paddy has been developed. Paddy is heated at 70*c for 10 - 15 minutes, in 10% sodium hydroxide solution, to reveal bug feeding spots on the grains. Studies on the incidence of the bug indicated that the bug (i) mi- grated from harvested fields to maturing fields, (ii) incidence was higher in fields with mixed varieties than in those with pure varieties and (iii) infests about 40 and 71% of the areas in autumn and spring crops respectively and thus about 53,000 ha. out of a total of 110,000 ha. require to be treated annually, for its control.

Bug damaged grains show up much less in white rice than in parboiled rice. Further, damaged grains get broken in polishing of white rice and thus by removing brokens, it was possible to get a good quality of white rice from bug damaged paddy. During soaking of paddy in water, for preparation of parboiled rice, immediate removal of light floating grains (bug damaged, unripe and shrivelled grains), resulted in better grade of rice,

Most important storage pest of bagged paddy was Sitotroga cerealella

(Olive), followed by Rhizopertha dominica (fab.) and Tribolium castaneum

(Herbst.). Studies on duration of toxicity of nine insecticides on jute sacking and time required to knock-down adult cerealella indicated that phoxim and pirimiphos methyl were of importance for control of this pest. Ap- plication of 0.25% phoxim emulsion at 150 mg a.i./m2 on exposed surface of stacks of bagged paddy, controlled and prevented the infestation by the moth for six months. Residues on jute of phoxim and pirimiphos methyl were quite - 187 -

toxic to adul R^ dominica and of pirimiphos methyl to adult T, castaneum. These

insects got killed when crawled out to the treated surface, however they contin-

ued inside the bags. The amount of insecticide used to control S^ cerealella

depended on the stack size. One litre of 50% phoxim E.C, protected about 3,800

tons of bagged paddy.

REFERENCES

Anon. 1970a. Technical data 3heet, May, 1970. Pirimiphos methyl, Plant Protection Ltd.

Cleare, L.D. 1961. Rice storage investigations. Pub. No. 1. The climate of British Guiana I. Coastlands and near inland areas. Dept. of Agriculture, British Guiana.

Cleare, L.D. 1962. Rice storage investigations. Pub, No, 4.

Courshee, R.J. 1959. Drift spraying for vegetation baiting. Bull. Entomol, Res., 50 : 355 - 70.

Gaines, T.B. 1960. Acute toxicity of pesticides to rats, Toxicol, and Appl. Pharmacol., 2. : 88 - 99.

Lofgren, C.S. 1970. Ultra low volume applications of concentrated insecticides in medical and veterinary entomology. Annual Rev. Ent,, 15 : 321 - 342.

Mc. Donald, L.L. and Gillenwater, H.B, 1967. Relative toxicity of Bay 77488 and Dursban against stored - product insects. J. econ. Ent,, 60 ; 1195 - 1196.

Pradhan, S. 1969. Increase in India's pest problems. Span, 12^ (2) : 81 - 83.

Wilbur, D.A., Bell, K.O. and Hopkins, H.G. 1970. A test for stink bug and fungal damage in green rice. J. econ. Ent., 63 : 982 - 983. Table I. CouCrol of peats by drift spraying, using a ao^orised knapeeck aprayer

Mo. of ha. Width of atrip Tiaa required treated per treated la one to apray one PeatS Treataent per ha. cankful (11 peasing ha. (ainutea) litrea) of (aetree) apray

1. Rica cacerpilla, Spodopter Penitrothicn eaulaion at 170-250 ga. a.i. in

fruftiperda S, b A. 3.5 litre* apray fluid 3 9 21

2. Dipterous aceo aaggnt, Paaitrothion eauleioa at 250 gn. a.i. in

llydrellia ap. n., nr. 3.5 litrea apray fluid 3 9 21

apinicornia Creaaon, - 188

3. Long-homed graaahopperBt Moaocrocophoa, BHC, malachion and

Neoconocephalua ap. and dieldsin eaulaiona at 270 ga, a,i, in

Caulopaia cuapidaca Soudder* 11 lit&ea apray fluid. 1 6 3Q

4. Paddy bug, Oebalqa (i) Monocrotophoe at 120 ga, a.i, in 11

poecila (Pallaa) litrea of apray fluid. 1 6 30

(ii) Carbaryl auapenaioa at 1.4 kg a.i.

in 44 litrea of apray fluid. 0.25 6 60 Table IV, Incidence ot see* barer end 'break In stem1 in paddy crop at Spring, 1971

No, at Ha. of tiller* Percent infeeted cillere from Fercent whita heada* Variety flelda due to eaapled all tillera apparently healthy Scea borer 1B in ate* tiller* atea borer '9 in ateaf a tea borer 1B in atea'

Stap Bonnet 19 3.3 33.5 0.4 29.9 0.0 59.3 23.0

Hybrid ft ft 7.5 14.6 1.1 11.7 0,0 37.0 60.0

Hybrid 8 7 6.6 9.4 3.0 4,7 0.0 55.ft 40.8 - 189

Hybrid S 3 7.5 8.0 0.6 4.2 0.0 47.5 50.0

Hybrid S 3 6.3 3.9 0.0 2.6 0.0 45.0 30.0

B.C. 79 5 4.7 6.2 3.7 6.0 0.0 10.0 86.0

t *Twenty white heada vera uprooted ac r andoa froa each field and we re analyzed. - 190 - 7 5 9 5 4 9 9 0 7 1 7 8 0 0 0 1 5 9 ! S 10 7 1 0 3 2 4 7 PCi'lC G X I i 4 0 5 c 0 0 0 0 0

i 1 13 6 1 5 2 8 7 0 0 0 0. 0 0 1 2 5 1 5 4 1 4 1 0 3 tl 2 7 9 6 4 8 a 9 2 8 6 4 0 0 0 0 I 1 3 4 5 6 £*t e < 8 9 0 0 vanecie * 0 0 0 0 0. 0 1 4 1 6 2 2 3 1 2 le t Dec. . c 3. 7 3, 7 7. 4 3, 7 2 7 0. 0 o. a 0. 0 0. 9 to 18. 5 22. 2 40. 7 1 7 3 4 0 0 B o 0 2 3 8 4 3 a 0 0. 0 1 7 1 3 0 2 6 1 2 6 3 A Mixe d VArl e o. a 0. 0 0. 0 0. 0 0. 0 0. 0 0. 0 0. 0 33. 3 4 33. 3 33. 3 a 0 0 0 c 0 0 0 0 0 0 2 5 2 5 0 2 5 0 2 5 0 S 1 2 4 8. 3 0 0, 0 a, a 0 0. 0 16. 6 50. 0 0 25. 0 0 0 Hu e telle 1 3 8 0 2 1 9 5 . 0 0 k 0 3 6 21 . 2 6 1 0 5 C 7. 1 3. 5 2 8 7. 1 7. 1 7. 1 0. 0 0. 0 17, 8 21. 4 28. 5 19t b Oct, ; 20tJ i Oct . t o 5t h Nov en d 22n

a 3 6 5. 6 2. 8 2. 8 0. 0 0. 0 U. l 13. 9 16, 6 22. 2 25. 0 0 11 3 5 Tabl e y . Exten t o qualit los du padd bug & [ 8 20t h Oct . c 5. 7 8. 5 0. 0 0. 0 8. 5 0. 0 22. 8 11. 4 20. 0 22. 8 Frequenc y distributio n o f bu g dawage d padd aaaple e (p.rceae )

ivom 3. 3 3 0 3. 3 3, 3 6. 6 0. 0 0. 0 0. 0 0. 0 0. 0 16, 6 16. 6 iO. O 13. 3 26* 6 & 5 5 a 3 5 , 4 . 8 * 0 0 14 . 10, 9 3 0 9 21 . 3.0 . 7 9

1 5 6 3 . 1 3 6 3 2 3 1 0 0 is . 7 la . 12 . i; . 28 . 1 0.0 0 1.001-1.50 0 1.501-2.00 0 2.001-2.50 0 analyze d 4.501-5.00 0 4.001-4.50 0 2.501-3.00 0 3.001-3.50 0 3.501-4.00 0 0.751-1.00 0 0.501-0.75 0 0.001-0.12 3 0.126-0.25 0 0.251-0.50 0 x I t ele o include s 2 1 en d 7 senple e f varietie D-5 60A respectively . X A,f t en d C repreeea (b e padd y receive No . o f eaaple * daaage d grain , Claaae a o f bu g (percen t b y weight )