Coffee Berry Disease

Abstract

Coffee Berry disease is caused by a mutant pathogenic strain of Colletotrichum coffeanum Noack which has spread throughout tropical Africa from its point of origin in Kenya. Fruit is attacked in all stages, and total destruction of the crop can be caused. The disease was confined for many years to the higher altitudes, because suitable conditions of temperature and humidity were infrequent in the lower ones. Following the inception of a wetter and cooler climatic phase in E. Africa in 1961, coffee in the lower altitudes is now attacked. Infection of the fruit is initially by infective conidia produced on the maturing wood of the twigs, where the pathogen "overwinters". When one crop only is on the tree, this inoculum is more important than that from lesioned fruit; but where a series of over-lapping crops is present, the reverse is the case. In the former situation control can be based on reduction of inoculum from the twigs: in the latter, however, this is ineffective, and control can only be achieved by a series of protective sprays. Varieties of coffee vary greatly in susceptibility to berry disease. No commercially acceptable variety is, however, completely resistant, although genetic material embodying resistance is available.