Important diseases of cocoa and their management
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Date
2007-02
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Though several diseases of cocoa have been reported from cocoa growing countries, only a few diseases are economically important. Among the nursery diseases, seedling dieback caused by Phytophthora palmivora has been found to be a serious problem during rainy season. Severity of the disease is very high in nurseries with very young seedlings during rainy season and warrants control measures. Pod diseases are vers' important from the economic point of view as they cause direct loss in yield. Black pod disease cause by Phyiophinora spp. occurs in all cocoa growing countries during rainy season. In India too, it is a majour problem owing to great econoic loss it causes. Phyiophihora palmivora, P. capsici, P. megakarya and P. citrophihora are the major Phyiophihora species causing this disease. Effective control of black pod disease can be achieved through integrated disease management practices. Cherelle rot causes by Colleioinchum gloeosporioides is often mistaken as physiological wilt of cherelles due to close resemblence in the symptoms. Cherelle rot is controlled by spraying mancozeb or carbendazim. There are several other than causing pod rot of varying intensities in different countries. Among the fungal diseases affecting trunk and branches of cocoa, witches broom, vascular streak dieback and stem canker have been identified as 'major problems. Witches broom caused by Crinipellis perniciosa is a major threat to cocoa industry in some of the cocoa growing countries. An integrated disease management strategy consisting of phytosanitation, spraying with chemicals and use of host resitance. has been recommended based on the studies conducted under the international witches broom project Several fungi like Phyiophihora spp., C. gloeosporioides, Fusarium spp. and Marasmius spp. cause foliar infection. But it may attain epiphytotic proportion only under certain environmental conditions. Cocoa swollen shoot disease caused by virus is the most economically important disease. It is still a major limiting factor in cocoa production in Ghana and Nigeria. Use of resitant/tolerant accession appears to be the ultimate solution to this problem. Since some of the diseases like witches broom, Moniliophthora pod rot, cocoa swollen shoot etc. are confined only to certain countries, strict quarantine measures are necessary to prevent the introduction of these diseases into other countries.
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IPM systems in agriculture. vol 6. Cash crops 1999 p-401-421