A Survey of Coffee Diseases in Nigeria

G.A. FILANI

Printed at the CRIN Internal Printing Unit and published by . Cocoa Research Institute of Nigeria Gambari Experimental Station P. M. B. 5244, Ibadan. July 1976. A SURVEY OF COFFEE DISEASES IN NIGERIA

G. A. FILANI, Cocoa Research Institute of Nigeria, Ibadan

ABSTRACT

Coffee is cultivated over large areas of Nigeria, particularly in the Southern parts where Coffea canephora ("Robusta") is scattered over wide areas in Oyo, Ondo, Ogun, Bendel and Kwara States and in the riveraine parts of the Northern States . is grown only on the Mambilla Plateau in the Gongola State where the cool weather is favourable to easy cultivation of this variety.

Coffea canephora is the hardier of the two varieties and its most important diseases include the following: leaf blight or leaf scorch caused by Botryodiplodia theobromae, and the brown leaf spot caused by Cercospora coffeicola. The only berry disease observed was a pink mould identified to be a combination of Fusarium and Gloeosporium spp. Most of these occur during the dry season when the crop is subjected to water stress, and the plants quickly recover when the rains b.egin.

The most important disease of Coffea arabica is the leaf . The Orange rust (Hemileia ·vastatrix) is more predominant on older trees in the field, while the Grey rust (Hemileia coffeicola) is more associated with seedlings in the nursery. The Brown leaf spot (Cercospora coffeicola) and the Hail-Stone damage are the other predominant leaf diseases. No incidence of Coffee Berry disease was observed during the survey.

Both varieties of coffee suffer from various nursery diseases, but the most important of these are seed-decay and seedling root-rot, and the most closely associated fungi are Pythium ultimum, Rhizoctonia solani and various Fusarium spp. INTRODUCTION

Coffee farms are scatered over large areas of Nigeria particularly in the Southern parts. There are many species of this crop, but broadly, the main ones cultivated are Q;_ arabi ca and h canephora or "Robusta". h canephora is grown mai nly in parts of Oyo , Ogun, Ondo, Bendel, Kwara and the riverain parts of the Northern States where the annual r ainfal l ranges from 100 - 200 em. but too hot to support the culti vation of Coffea arabica. In the Oyo , Ogun and Ondo States, approximately 87% of the coffee acreage belongs t o peasant farmers whose hol dings range from one to five acr es . The rest of the coffee is grown principally in plantati on and almost all of these are owned by the Western State Agricultural Investment Corporation (WSAIC), (Sands, 1958) .

h arabica is grown only on the Mambilla Plateau of the Gongola State. Thi s Plateau lies in the Gashaka­ Mambilla Division of the Sardauna Province of the State, and it rises to a height of 1500 - 1900m . above sea level , and i t covers approximately 4000 sq. km. (Are etal 1965). The weather is cool with a mean minimum temperature of 65°F and a mean maximum of 85°F. The rainfall, 1500 - 2000mm . per annum , starts during early March and continues to the end of October. Most of the farms are owned by the individuals, and the state Ministry of Agriculture is encouraging more farmers to plant coffee by supplying seedlings at very low cost , (lK per seedling), by giving advice on proper cultural methods , and by establishing model and pilot farms. Most important to the farmers , the New Nigerian Development Corporation (NNDC) provides a ready market for good quality and ripe cherries at the favourable price of 5K per 453.6gm. · The establishment by the NNDC of small hulling and drying pl ants at key locations means that farmers no longer have to process their own coffee , and a higher and uniform grade pr oduct can therefore be obtained . • During the survey, visits were paid, at least once every t wo months and where possibl e once a month throughout the year, to various locations where coffee is grown. Di scussions were held with the farmers with regards to their problems and disease specimens were brought into the labora­ tory for routine isolations and identification. Isol ations were made from specimens by first surface sterilizing by dipping in 60% ethanol and flaming before plating on Pot atoe Dextrose Agar (PDA) . Plates were examined everyday 3 and any fungal growth was quickly subcultured onto fresh PDA with a flamed needle . Cultures that could not be identified in C.R. I.N. laboratories we're sent to· the University of Ibadan B~tany Department. Figure I shows the locations and areas covered during the survey and Table I shows the approximate acreages of Coffee grown in different parts of Nigeria, while Table II shows the major diseases of coffee in Nigeria::- · · ·

FOLIAGE AND BERRLDISEASES

(a) Hemileia Leaf Rust

The Leaf rust disease caused by Berk & Bri. is by far · the most seri0us disease of coffee in Nigeria and in the world as a whole. This disease had led to the ruin of many coffee industries in Ceylon, India, Java, the Philippines and other regions of the world, and it is still a limiting factor for coffee production in many countries in Africa. At present, the disease is endemic in almost all the regions where coffee is grown and even now in Brazil which has been rust- free, the disease has become ·firmly established (d10liveira, 1971, 'Wellman, 1970). ~ arabica is very susceptible to this disease, while~ canephora is generally resistant, though 'the pustules may be found on the leaves of some trees . None of the Robusta trees present in Nigeria however, has been observed to be attacked, and there are no previous records of any attack. At the 1550 acre W.S.A.I.C. farm Owo, in Ondo State, where a few stands of £..:_ arabica are. growi.ng and whi~h are heavily attacked by the orange rust, no traces ;'of leaf spots ·have been found on the £..:_ canephora.

The two species of rusts - orange rust · ~ · vastatrix, and grey rust. !:!.:.. coffeicola Maubl. & Roger were found present on ~ arabica on the Mambilla Plateau. The or~nge rust which was found widespread on older trees of all the farms visited, produces yellowish-orange powdery, roundish blotches on the lower sur~ace of the leaves. When they first appear, the area affected by a single infection is about 3 - 4mm in diameter but it gradually expands until it fuses with other infeetions. In the early st.ages only a pale yellow spot on the leaf is visible but it becomes yellower as the infection progresses·:and?spo:te production ' commences. The upper surface of the leaf shows a yellow 4 area in the region of infection but the surface does not become powdery. The powdery appearance on the lower surface is due to the production of the orange · uredospores of the . The grey rust found only on very few farms and on seedlings in the nurseries is different in appearance . The part of the leaf that is affected is not so clearly defined. It spreads irregularly through the leaf developing from an edge infection to all parts of the leaf. Spores occur also only on the lower leaf surface and appear as clumps of uredospores.

In a severe attack of rust, the leaf surface may be completely covered with rusted areas, and as these. areas age their centres die, turn brown and dry out. This leads to heavy defoliation ·and therefore loss of yield .

. The Coffee Research Centre, Oeiras, Portugal, has differentiated 26 physiologic races of H. vastatrix from 1269 samples receive~ from 36 different-areas of the world including Nigeria from where races II and III have been identified (d'Oliveira, "1971) .

(b) . Brown Leaf Spot

This disease caused by Cercospora' ·coffeicola Back. and Cooke, attacks both varieties of Coffee and it is sometimes referred to as Cercospora Leaf Spot . It is one of the most common and yet least damaging of Coffee leaf diseases. The spots,. which are brown in colour vary in sizes from 3mm to 8mm. In some cases, particularly on the Mambilla Plateau, the spots were observed to coalesce thus resulti.ng in consi­ derabQe leaf fall. This disease was also found in one of the nurseries in Gembu and Kusuku, Mabilla and, under condi­ tions of severe infection, can lead to def~liation, die-back of seedlings which then become unfit for transplanting in the field.

(c) Leaf Blight or ·Leaf Scorch - I Jfhis condition was observed ·to be most prevalent on both varieties of Coffee during the dry season. The affected leaf starts drying up from the tip which turns .dark brown. It becomes curved outwards and under severe conditions the leaf roles up completely and then drops. This spreads to other leaves and eventually the whole ·brancb is infected and becomes dried. Under very severe water stress this 5 may spread to the main trunk and the whole plant starts to die back. When the dead leaves and laterals were plated on PDA , Botryodiplodia theobromae was the frequently isolated fungus (Filani, 1972), ~ theobromae which in this case is regarded as a post- drying invader of dead tissues, is how­ ever, a ubiquitous weak pathogen which has also been found on cocoa pods (Okaisabor, 1968), and on stored nuts, leaves and roots of Cola nitida (Adebayo, 1968). Further observa­ tions made during the w;t season showed that many of the plants quickly recover, but in most cases they have to develop new laterals .

(d) Pink Berry Mould

In many farms, particularly in the Ogun, Oyo and Ondo States where farmers have for a very long time neglected their farms, a pink mould was found to occur on berries, particularly of light crops which have been left unharvested. Isolations from these showed that the main fungus is Fusarium spp. In many other cases, particularly on the Mambilla Plateau, berries near the tips of branches could not develop properly and therefore were in a weakened and exposed state and were subjected to sun scorch and subse­ quent invasion by Fusarium and Gloeosporium spp. This situation was particularly noticeable about December when a considerable proportion of the light crop did not fully develop, mainly because of water stress. Many such perries were invaded by Fusarium and Gloeosporium spp.

(e) Coffee Berry Disease

, Coffee Berry Disease (CBD} is characterised by lesions, usually multiple, that are brown and sunken on green berries. This disease is caused by Colletotrichum coffeanum Noack . When this fungus attacks ripe berries the condition is known as Brown Blight . This is characterised by brown lesions, with minute black dots which are the sporing bodies o'f the fungus. Neither of these two conditions have been· observed by any previou~ workers (Gorenz et al 1972). How­ ever, reports of suspected outbreaks have been received from the Plateau. Subsequent investigations by the author have confirmed the presence of both CBD and the Brown Blight on some isolated farms . These occurrences have, however, been observed to ~e restricted to the old 1953 plantings on the Ministry of Agriculture farm at Gembu which have been.left without pruning and fertilizer application coupled with low levels of management practises. 6

In Kenya where CBD is regarded as the major disease of coffee , it is most severe at the highest elevations especially above l900m. and in pockets that remain cool and damp most of the year (Furtado, 1969) . The Mambilla coffee farms are below this level, and are usually on well venti­ lated slopes in a grassland areas and it is therefore hoped that these conditions would not constitute a major problem.

(f) Mineral Deficiencies

It is not quite clear if fertilizer application as a routine practice would result in any appreciable increased yield in coffee. However, some mineral deficiency symptoms have been found to occur in many farms on the Mambilla Plateau. This is more important because the Fulanis, who occupy almost all positions of authority, use most of the upland areas for grazing thus leaving only a small portion of land, usually the very steep slopes or sometimes the marshy valleys for the cultivation of mainly maize and coffee These slopes are heavily leached and consequently are low in plant nutrients . The most common symptoms observed were mild chlorotic narrow leaves in new flushes, and fairly stunted plants were observed on some farms . These appeared to be similar to symptoms described for zinc and nitrogen deficiencies (Bpuld, 1970).

(g) Over-bearing

This condition has been observed mostly on ~ arabica on the Mambilla Plateau and it occurs when the plant is unable to carry and support the number of berries produced on the branches. Loss of leaves, and therefore reduced photosynthetic activity or other factors, such as excess berry pr oduction, could be responsible for this condition and due to the heayY cr op there is a general depletion of sugars and starch r esulting in die-back of immature branches. The berries do not develop to maturity, they turn yellow and in many cases turn black and die.

(h) Hail - Stone Damage '

This condition which is mechanical in or1g1n occurs as a result of the cool nature of the weather on the Mambilla Plateau. During the wet season, rains are often accompanied by hail- stones which severely damage the leaf surfaces . A typically ?amaged leaf is torn into shreds, the leaf begins 7 to dry up from the torn edges , and eventually the whole l eaf dries up and drops . This can also lead to invasion by weaker pathogens and saprophytes.

ROOT AND STEM DISEASES

(a) Coffee Die-back

This disease , which has been observed widely on almost all coffee farms in Nigeria, i s the advanced stage of the Leaf Blight or Leaf scorch and it occurs under very severe drought or water stress. Infection, which starts from the leaves, spreads very ~uickly to the branches and then to the main trunk. If the dry season is not too prolonged, t he plant may recover during the rainy season. Usually, however , most of the attacked l ateral s never recover and the plants have to develop new ones on which fruits are set. Botryodiplodia theobromae is the most commonly isolated fungus from dead t issues.

(b) Root Rot

There were a few coffee trees on the Mambilla Plateau, growing near dead stumps of Eucalyptus trees which had been cut down. These coffee trees were found to be completely dried up and dead. The root system was dug out. and the white mycelial strands of Armillaria mellea (Vahl) Quelet were found under the dead bark. In a few cases, the leaves of some of the trees were j ust beginning to wilt, but root examination revealed the same type of symptoms. At various parts of the root system vertical cracks on the surfaces were observed. These observations have also been made in many ~ canephora farms in the Southern parts of Nigeria, particularly in plots with numerous decaying tree stumps.

SEED AND SEEDLING DISEASES

(a) Pre-emergence seed-decay

Coffee seeds are lost through decay in soil before germination and/or emergence due to attack by soilborne phytopathogenic fungi . Such losses are, however, not peculiar to coffee as they also occur to seeds of other crops. These losses in coffee are, however magnified when the seeds are s own without the parchment which acts as a 8 barrier to water absorption and therefore results in a long del ay in germination and emergence (Bendana, 1962). Records of losses have been very difficult to obtain apparently because the standard practice among the Nigerian farmers is to sow a large quantity of seeds from which enough would germinate and emerge for field planting. This practice has largely hidden the magnitude and importance of seed and seedling loss through decay . It has been found that in many cases losses could be as high as 50 - 70% (Filani, 1972) . Although quite a number of saprophytes like Penicillium, Aspergillus, Mucor, Trichoderma, Cunninghamella and Botryodiplodia spp. were associated with decaying seeds, the most important and most pathogenic were Pythium, Fusarium and Rhizoctonia spp. (Filani , 1971).

(b) Post-emergence seedling root-rot or damping- off

This is a condition that occurs principally in the nursery, i.e. when the germinated and emerged seedlings have been transplanted into the nursery beds or into polythene bags filled with nursery soil. In most cases losses as high as 40 - 50% have been observed in both varieties of corree. The attack, which is more severe under conditions of high soil moisture content, starts from about soil level, and spreads up the stem and down to the root system. The epidermal and cortical layers of the seedlings are destroyed thus leaving only the vascular system as a support for the whole seedling. A slight pressure either by wind, or more o~ten during watering, tilts over the plant breaking the vascular system thus resulting in the eventual death of the seedling. Under severe conditions of attack the vascular system itself may be destroyed and the seedling wilts and dies . The main fungi associated with this disease are various spp. of Fusarium and Trichoderma spp .

NEMATODE AND VIRUS DISEASES

C. arabica is known to be highly susceptible to nematode diseases . On tbe Mambilla Plateau some coffee plants have been observed to wilt and die suddenly. When such plants were dug out and the root systems examined, it was observed that a few of the roots developed swellings typical of nematode invasion. Some of the roots had decayed •and generally the system was very poor with very few secondary . re~~s . In other cases, the part of the root system just below the soil surface was swollen, and the whole plant developed very thin and long branches, with 9 chlorotic leaves. It was quite evident that the poor root system could not sustain proper growth of the plant . Eventually such plants lose their leaves and die . Nematodes have also been observed to invade the root system of damped off coffee seedlings in the nursery. However, these are thought to be secondary invaders the invasion of which has been facilitated by injuries from attack by Fusarium spp.

Four species of nematodes have been reported on coffee, Meloidogyne exigua, !1.;_ africana, and !:h. incognita (Whitehead, 1968). Generally these attack seedlings and they are not always damaging to trees. !1.;_ exigua may produce small ovate or pyroid galls on the roots of trees and seedlings; necrotic areas are also reported on infected roots. A few seedlings in nursery beds on various farms have been observed to· wilt and die. Such seedlings were found to be stunted and with chlorotic leaves, and examina­ tion of the roots of these seedlings revealed root swellings which are consistent with symptoms of attack by root knot nematodes (Whitehead, 1968).

Coffee has not been reported to have any serious virus infection, a situation which is surprising when it is realised that coffee is grown in such places and in close'proximity with many trees and other crops e.g. cocoa and cassava associated with virus diseases (Wellman, 1961). The common symptoms such as mottled and malformed leaves and shortened internodes which were found on Robusta and a strap - leaf type ~f growth on Arabica coffee in Uganda have not been noticed on any variety of coffee in Nigeria.

SUGGESTED CONTROL MEASURES FOR COFFEE DISEASES

No matter how hardy a plant may be, it is bound to suffer from a disease of one kind or another . Different varieties of coffee react differently to various diseases, but as a general rule, coffee is more severely attacked by diseases if the trees are weakened by drought, by overbearing or high temperature . The most important cultural practice considered by a lot of authorities, as perhaps, the most influential soil treatment that can be applied to ensure the best coffee production over a long period is mulching. This practice has been found to have a multiple effect on coffee as_ follows:- it conserves soil moisture during the dry season, increases nitrogen fixation in the soil, re_duces soil temperature, and supplies the much needed humus to the 10

soil (Wellman, 1961). This practice therefore results in a very healthy, green and vigorous crop which can better withstand the attack of pathogenic fungi particularly during the dry season when there is high water stress. Although mulching in itself does not prevent infections, it would, to a higher degree , pre- dispose the plant. xo with­ :stand the effect of infections, particularly of those like Leaf Blight , Die- back, Pink Berry Mould all of which are most prevalent during the dry season. Also mineral deficiency symptoms would be minimal since mulching prevents leaching and erosion of the soil which are a major land problem on the Mambilla Plateau.

Over- bearing perhaps results from a complex combination of bad management practices like incorre ct pruning , shading and mulching and lack of sufficient soil nutrients thus resulting in the tree being unable to support a full com­ plement of fruit production. Mulching as a cultural practice can correct some of these symptoms since moisture and humus are retained i n the soil.

The standard method £or the control o£ most £ungal pathogens on coffee , and on most other crops for that matter, is fungicidal spray. The most important diseases of coffee which are controlled by chemical application include Leaf Rust, Coffee Berry Disease, Brown Leaf Spot and pre- and post- emergence damping off of seeds and seedlings. Copper based fungicides are the most widely used all over the world, although efforts are in progress in the search for alternative fungicides particularly the new organic compounds . At present, in Nigeria, there is no standard spraying schedule against coffee diseases as we already have in cocoa, and this can be partly explained by the fact that ~ arabica, which is the most susceptible of the two main species in cultivation is restricted only to the Mambilla Plateau, a small and remote area of the Gongola State . However, Table III shows a few suggested chemical fungicides which can be used for the control of some of the coffee diseases present in Nigeria. Routine spraying of coffee by farmers using Bordeaux mixture against the most serious disease , Leaf Rust, is now being actively encouraged, and research work on other chemicals which are as good as the copper based fungicides currently in use, and perhaps cheaper in cost is being initiated. This is of particu1ar importance also with regards to tolerance or other side ·effects of copper sprays . It has been claimed by

-~---~-- 11 several coffee growers that copper sprays have increased the severity of CBD and its almost complete absence from unsprayed farms in Kenya has been cited as evidence to support this contention. It has in fact been shown ex­ perimentally that the pathogenic strain of C. coffeanum is substantially and significantly more abundant on sprayed coffee plants (Furtado, 1909) . It has also been claimed that fUngicides also ha"\re a marked "tonic" effect on coffee in that natural l eaf fall is retarded and yields are on the average doubled (Rayner 1957) . Consequently tonic spraying has been a widespread practice ih East Africa, and several different fungicides have been shown to yield similar results (Furtado, 1969). 12

CONCLUSION

The most serious disease of coffee in Nigeria, is Leaf Rust to which C. arabica is most susceptible. Simple cultural practices, particularly mulching aid the plant to withstand the effects of most other infections. Pruning as a routine practice, if properly done, confers many advantages on coffee:- the productivity is regulated, harvesting is easier, i nfestation by pests and diseases is limited since the pl ant is not too bushy, aeration is increased and spraying is easier and more effective ~Adenikinju, 1970). Failure to harvest regularly and promptly, particularly the light crop which many farmers in the West regard as non-economic, leads to over- ripening and subsequent invasion by Fusarium and Gloeosporium spp . which then act as inoculum source f or the main crop.

Ease of disposition of produce is a major contribu­ tory factor and incentive to good farm management and there­ fore production of high quality coffee. At present the Northern Nigeria Marketing Board guarantees a ready market for all ·farmers' produce in the North. The Gongola State Ministry of Agriculture also assists the farmer by supply­ ing seedlings at very low costs and by giving advice on proper cultural methods of cultivation. The result i s that coffee production is gaining importance in the State' s economy, and a lot of expansion is taking place. In the West, the farmer is faced with the problem of how to dis­ pose his produce. At present, some of the coffee is sold away. to buyers from Dahomey, a neighbouring country, while most of it is just stored until a buyer comes along, usually at the times when the farmer needs money badly and is there­ fore ready to give away his produce at any price dictated by the buyer. This being the case, the farmer has lost all interest in his coffee farm. The farm is left unkept, often the berries are not harvested, and in many cases now the coffee is being cut down to be replaced by cocoa. Any suggestion to keep the farm clean is treated with complete cont~mpt and ignored. Fortunately all the coffee in the Oyo, Ogun and Ondo States is Robusta which is tolerant to the most serious diseases terms of spraying pumps and chemical s , and if the Western Nigeria Marketing Board can guarantee a ready market for the produce as it provides for 'cocoa and oil- palm produce, the farmerts attitude to his coffee farm would change , · some steady income would be realised, and better sanitation then maintained on farms will result in reduced incidence of some coffee diseases . 13

LITERATURE CITED

1 . ADEBAYO, A. A. (1968) · Diseases of cola plant. PANS (Pest Articles and News Summaries) 14 (4): 325 - 327 .

2. ADENIKINJU, S. A. (1970) Notes on routine pruning of coffee farms. (Unpublished).

3. ARE, L., ODEGBARO , 0. A., OLORUNTOBA, B.S. (1965) Some important problems affecting the producti on of Coffea arabica on Mambilla Plateau. Nig. Jour . Agric . Soc. 4: 45-48.

4. BENDANA, F. E. (1962) The physiology of coffee seeds . 11. Factors retarding germination: parchment . Coffee (Costa Rica). ~(15): 76-78.

5. BOULD, C. (1970) Atlas of coffee pests and diseases . English Press Ltd. London. pp. 40-46.

6 . FILANI, G. A. (1971) Observations of fungal diseases of Coffee In Nigeria. Cocoa Research Institute. Annual Report 1969-70 Ibadan, pp. 61-63.

1. FILANI, G. A. (1971) Chemical treatment of coffee seeds in relation to germination, emergence, and control of seed-borne fungi . Turrialba "22 (1): 40-46.

8. FURTADO , I.. (1969) Effect of copper fungicides on the occurrence of the pathogenic form of Colletotrichum ·coffeanum. Trans . Bri. ·St>c. ,2l(2): 325- 328 .

9 . GORENZ , A. M., OMAZI , 0. C., A and MCDONALD,- D. A. (1972) Survey of Arabica coffee .on the Mambil la Plateau for the presence of Coffee Berry Disease . (Unpublished) .

10. HAARER, A. E. (1971) Coffee Growing. London, Oxford Uni versity Press. pp . 93-106.

------14

11. OKAISABOR , E. K. (1968) An active fungal parasite of Phytophthora palmivora. PANS (Pest Articles and News Summaries) . 14: 253- 360.

12. d ' OLIVEIRA , B. (1971) Coffee Ru~ts Research Centr e , Oeiras, Portugal. Report . p . 18 .

13 . RAYNER , R. W. (1957) Tonic copper spray of coffee . Pr oc . Nairobi Scient. phil. Soc. ~:12-16

14. SANDS, F. B. (1958) Coffee Production in Western Nigeria. M.A .N.R., Ibadan. p. 34.

15. WELLMAN , F. L. (1961) Coffee. World Crop Series. Leonard Hill. pp. 201-203; 269- 270.

16 . WELLMAN, F. L. (1970) The rust Hemileia vastatrix now firmly established on Coffee in Brazil. Plant Disease Reporter. 54(1): 539- 541 .

17. WHITEHEAD , A. G. (1968) In Le Pelley. Pests o~ Coffee. Longmas, Green & Co. pp. 407-422.

' 15 Table I Coffee - producing Areas in Nigeria

Total Area of Production Type of Coffee Acreage

Western State Egbado Division 2065 . 3 Robusta & Liberica. Egba " 541.9 Robusta & Liberica. On do II 1476.6 Robusta & Liberica. CMo II 814.4 Robusta Ekiti " 571.1 Robusta Oki tipupa Division 16 . 5 Robusta Ibadan (Including Oshun) 912.5 Robusta & Liberica Oyo 594.5 Robusta & Liberica Ijebu 5 . 0 Robusta

La~os State Ojokoro 48.7 Liberica Agege 1.0 Liberica Mid - West Benin 64.7 Robusta & Liberica Uhonmora 15 . 0 Robusta Benue Plateau Oturkpo 3. 0 Robusta Reav 3.0 Robusta North Eastern State Gerrbu ) Kusuku ) 2 ,600 Arabica Local farms ) North Central State Jemaa 12 . 0 Robusta North Western Stat e Puji . ) Ebo ) 15 Robusta Nupeko )

Kwara QJalwao ) Ocharu ) 400 Robusta Ochanja )

South Eastern State Ikom 50 Robusta Table II.

The Main Diseases of Coffee In Nigeria

Variety Disease Symptom Causal .Agent S tatus affected

1. Coffee Leaf Rust a. Orange ·Rust Yellow or Orange Hemileia vastatrix Coffe a arabi ca The most serious· leaf round blotches of Berk. & Br. disease of coffee; spores ( unredos­ often restricted to pores ) produced the field . ~ by the fungus on m the lower sur­ faces of l eaves.

b. Grey Rust Infection is H. coffeicola C. arabica Not very irrportant general. Spores Manblanc . & Roger. and occurs only in occur on the lower the nursery parti­ surfaces of leaves cularly under as closely set conditions of high grey clumps that humidity due to can be seen excessive shading. easily. Table II continued .

Variety Disease Symptom Causal Agen t Status affected 2. Brown Leaf Sma ll brown spots Cercospora coffei- C. arab:i,ca Can become a very on the l eaves , cola Berk . & canephora seri ous disease in Spot -c. ' usually with reddish CooJce . the nursery bed and brown margin turn- under severe ing grey at the conditi on s of attack , centre with age. leads to defoliation thus renderi ng a ~ lot of seedlings -..3 unfit for transplanting.

3 . Hail- Stone Shreded coffee (Mechanical Damage) c. arabic a Very important under leaves . Hail-stones hitt- - conditions of high ing the s urfaces rainfall. Mutilated of leaves lead- leaves become easil y ing to serious invaded by sapro- mudlation of phytes . Can lead s uch leaves . to heavy defoliat ion .

------Table II Continued. - Variety Disease Causal Agent Status Symptom affected

4, Leaf Blight. General wilting of High-water stress C. arabica Can lead to very the plant browning under excessive C. canephora Serious losses of crop of leaves and even­ drought under very severe tual die-back. drought and water- s tress. Pre-disposes the plant to attack by weak pathogens like Botryodiplodia theobromae .... 5 . a. Coffee Berry Fungus attacks Collecto:richum C. arabica 00 Disease (CBD) green berries coffean un. causing brown Noack spots, at the advanced stage the berry turns compl­ Has just been etely brown to identified on the black and the Mambilla. Usually beans inside are a very serious destroyed. disease of coffee which if not b. Berry Brown Fungus attacks Colle ct otri churn C. arabica contained properly Blight. ripe berries . coffe an un. can affect flowers Brown lesions and sometimes with small black leaves. dots are deve loped. Table II continue,

Variety Disease Symptom Causal Agent I Status affected

6. Pink Berry Pink coloured mould Fusari urn spp. c. arabica Starts with the unhar- - c. Mould growth on dried - caneEhora vested light crop berries which have in October, & been left tmhar- Novenber, but can vested. be very serious if .. allowed to spread to the main crop o f July and August of the following year can also result in .,.a (0 die-back ef fruiting branches .

7. Over-bearing Berries tum Ph:ysiologi cal C. arabica Occurs when a tree yellow and do CODdi tion. c. caneEhora cannot support the not ripen n ormally , - nunber of berries may tum black it can sup port and die . physi ologically. Often leads at a final stage to die-back of bearing branches. Table II continue d .

Disease Symptom Causal Agent Variety Status affected

8 . Pre-emergence Decay of seeds at Pythium spp. c. arabica Occurs principally seed-decay the pre - germina- - when seeds are Rhizoctonia sown tion and/or " c. canephora emergence stages - wi thout parchment . Trichoderma " Losses up to 70% have been recorded . Fusarium "

t-:) 0 9 . Post-emergence Contriction and P . ultimum c. arabica Occurs in the - - s eedling root- rottening of the nursery beds rot or damping stem at soil -R. solani -c. cane12hora parti cularly off level. Even- under condition of tually the Fusarium spp . high soil -moisture . seedling falls Losses as hi gh as over and dies . 6 0% have been recorded . . . - .. Table III

A few suggested 01emical sprays for the control of some Coffee diseases in Nigeria. These suggestions are based on thP results of research by the Author and on thei r experience in East - Africa

Disease Fungicide Active Ingredient Dosage and method of application ·------1------t-J l. Leaf Rust l . Bordeaux Mixture CuSo . SH 0 l%)Knapsack pre3surised ~ 4 2 pump or motorised 2. Perenox CuO 1%) Mist bl<:Mer

2. C. B.D . Captafol I ~ -( 1 , 1 , 2 , 2 - tetrachlo- 0 . 6% . Knapsack pressurised roethylthio) pump or motorised (Orthodifolatan 80 W). I - 4- cyclohexen- 1 , 2 dicarboximide Mist blower.

3 . Cerosspora 1 . Bordeaux Mixture CuSo .SH 0 4 2 Brown Leaf Spot 2. Peren ox CuO r

Table III continued .

Dosage and method Disease Fungicide Active Ingredient of application

4. Pre-emergence Seed- Dressing seed- decay with a. Captan N-(trichloromethylthio)- 0.2% W/W ) Chemical seed-d:ry 4-cyclo hexen -1,2 - ) dusting before di thiocarboximide ) sowing. ~ b . Thiram Tetramethyl thiuram ) 1:\:) disulphide 0 . 2% W/W )

5 . Seedling Root a. Ches humt Cu So . SH?O 6.25gm. 2:11 mixture of CuS0 4 4 Rot. Conpound and (NH )co ( 5 70 ppm Cus0 ) 2 3 4 in 2 lii:res water is used t o drench the soil for a few days before sowing. COFFEE PRODUCING AREAS OF NIGERIA.