CARD FACT SHEET Agricultural Caribbean Agricultural Research Credit Bank and Developnint Institute of Jamaica Ltd.

COFFEE Prepared by Marlene Pereira July 1995

IS LEAF RUST A SERIOUS DISEASE? Coffee Leaf Rust is regarded as the most devastating and widespread disease of coffee throughout the world. In fact, it was the devastation of the coffee indus- try in Ceylon. now , by Coffee Leaf Rust in the 1870s which inspired disease research on coffee. However, Coffee Berry Disease, which apparently only occurs on the African continent and which affects young coffee berries, is currently regarded as a more serious dis- ease.

a) Symptoms ofCoffee Leaf Rust on the top of SYMPTOMS coffee

The disease is identified by orange to yellow powdery on the underside of leaves. These spores are held to- gether in circular spots which appear yellow on the top side of the leaves. Be- fore spores are produced, all that is seen are the yellow spots. Older spots with spores eventually cause death of the af- fected leaf tissue which appears brown and dry.

b) Symptoms ofCoffee Leaf Rust on the under- side ofcoffee leaves EFFECTS OF COFFEE • Rainfall is perhaps the single most LEAF RUST important environmental factor con- tributing to disease development.The • The rust (Hemileia vastatrix) kills the section of the leaves on development of coffee rust in any sea- son can ultimately be related to the which it grows. rainfall pattern of the area or region. • The disease reduces the ability of the Rainfall provides the moisture needed trees to manufacture carbohydrates. for fungal germination and dis- • This subsequently leads to fewer ber- ease spread. In fact, if moisture is ries at harvest. not present on coffee leaves, The disease can cause severe leaf spores will not germinate and the fall or defoliation which is ultimately disease will not develop. followed by poor vegetative growth • Disease will develop and spread dur- and reduced yields. ing the rainy season, but because it takes approximately 3-6 weeks for IDEAL CONDITIONS FOR spores to germinate and infect the DISEASE DEVELOPMENT leaves, the maximum amount of dis- ease will be seen early in the dry • A susceptible host plant — season. arabica — is the species most sus- ceptible to this disease. Ninety per- • Temperatures between 15°C and cent of the coffee trees grown in Ja- 32°C are favourable for coffee rust maica are of this species. development, 21°C to 25°C being the most favourable. • Host density or plant spacing — The • Altitude is important to disease de- closer the trees are planted, the faster velopment insofar as it affects tem- the disease develops due to the longer perature. At altitudes above 1700 m, time moisture remains on the leaves. night temperatures frequently fall be- Conversely, the further apart the trees low 15°C, preventing spore germina- are planted, the slower the disease tion. develops, because moisture does not stay on the leaves long enough for • Excessive shade — Indications are fungal spores to germinate and the that shade is no longer regarded as a disease to develop. factor which assists in disease de- velopment but, rather, contributes to High — yielding trees are especially • maintaining a moist atmosphere susceptible to rust and other dis- which favours spore germination. eases. This is because trees come under stress, or become weakened • Exposure to light causes increased from heavy bearing. Most of the car- productivity which in turn puts the bohydrates produced by the trees are trees under stress causing them to used up to produce berries, leaving become more sensitive to the dis- very little energy to ward off diseases. ease. CONTROL ant to several strains of the fungus but The control of coffee leaf rust must be not all. However, the cup quality of the carried out by a combination of agro- above varieties is inferior to C. arabica. nomic, genetic and chemical interven- tions. The reliance on chemicals for the (C) Chemical control control of pests and diseases has be- Chemical control of pests and diseases come addictive. As a result of this farm- may be carried out after it has been de- ers seem to be overlooking the impor- termined that it is necessary. The com- tance of maintaining healthy coffee trees. mon practice of applying a "cocktail" of It must be constantly reinforced, that a insecticides and fungicides is an unnec- healthy tree, like a healthy body, is best essary waste of resources and is envi- able to fight off attacks from pests and ronmentally hazardous. diseases. Chemicals recommended for the con- (A) Agronomy trol of coffee leaf rust: Healthy trees are achieved through proper Copper fungicides, eg., copper crop care which includes: oxychloride and Kocide© which are • the proper and timely application protectant fungicides are still the most of fertilizers when required, to the cost effective. Their 'tonic' effect is well roots of all trees known, boosting plant growth and caus- • pruning away of dead branches ing leaf retention. This is perhaps why • pruning away of gormandizers severe leaf fall or defoliation, the devas- • the removal from the coffee grove tating end result of the disease, is not and burning of pruned branches common in Jamaica. It is also impor- and stripped and fallen berries tant to note that fungi have not built up • the general cleaning and weeding resistance to copper. (not bare weeding) of the field, Rate of application: Apply copper at when needed 4-6 weeks intervals during the rainy sea- son at a rate of 3-5 kg in 250-700 L/ha (B) Resistant Varieties* or 6.6 - 11.0 lb in 66.0 - 185 US gal water/2.5 acres. One application at the The most successful, resistant variety start of the rainy season is advised. If still remains the "Hibrido de Timor", a using Ultra Low Volume applicators cross between C. arabica and C. (ULV), 1-3 kg in 20 L of an oil/water canephora. This variety has been widely emulsion/ha. used in crosses with Caturra to produce "Catimor". This hybrid bears well but is not resistant to all the rust races. Other resistant varieties includg robusta hy- brids, e.g. arabusta, icatu as well as * Check with the local authority for varietal arabica hybrids. These too are resist- recommendations Bayleton© (triadimefon), a systemic more frequently than Bayleton©. fungicide, is highly recommended . NB: The above are recommendations This fungicide has provided the best re- from research conducted in other coun- sults in controlling rust to date. It is re- tries and not based on local field tests. ported to have curative properties, i.e., the disease disappears. However, this fungicide is very costly. Rate of application: A single applica- tion during the rainy season at 71 g - 567 g/ha or 0.16 lb - 1.25 lb/ 2.5 acres, REFERENCES with follow-up applications of a protectant fungicide at 4-6 weekly intervals. 1. Anonymous. (1982). Agricultural Chemicals, Book IV - Fungicides, ed. Thompson, W.T. NB: More than two applications of 1982-83 Revision. Thompson Publications, U.S.A. 181 pp. Bayleton© during a season may have 2. Anonymous. (1986). Growing Coffee in adverse effects on yield. Jamaica. Compiled by Penelope Budhall. Pub. Coffee Industry Development Company Ltd. Sicarol© (pyracarbolid) is also effec- Kingston 10, Jamaica. 99 pp.

tive. It causes infected leaves to fall off 3. Cambrony, H.R. (1992). The Tropical Agricul- prematurely, inhibiting disease develop- turalist-Coffee Growing. Pub.CTA, The Macmillan Press Ltd. London and Basingstoke. ment and spread. Once the leaves fall 118 pp.

off immature fungal spores will not de- 4. Coste, R. (1992). COFFEE -The Plant and velop any further. However, mature the Product. Pub. Macmillan Press Ltd, London and Basingstoke. 328 pp. spores will survive for a while until they 5. Waller, J.M. (1987). Coffee diseases current dry out or are dispersed to other leaves status and recent developments. Rev.Trop. on the tree. Pl. Path. 4: 1-33.

6. Wrigley, G. (1988). COFFEE - Tropical Agri- Rate of application: Make the first ap- cultural Series. Pub. Longman Scientific & plication when disease symptoms first Technical co-published with John Wiley & Sons, Inc., New York, 639 pp. appear at a rate of 0.5 - 0.1% active in- gredient. This chemical may be used

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Produced under the auspices of the Agricultural Credit Bank's Hillside Farmers Support Project in conjunction with the Caribbean Agricltural Research and Development Institute. The project is funded by the International Fund for Agricultural Development, the Government of the Netherlands and the Government of Jamaica