Incidence and severity of coffee diseases in smallholder plantations in northern Malawi

A two-year survey (1998, 1999) was conducted in northern Malawi to estimate the occurrence of coffee diseases, with emphasis on coffee berry disease (CBD) caused by Colletobichum kahawae, in relation to management practices on smallholder plantations. A total of 113 farms was visited in five extension planning areas (EPAs) which grow coffee, and the prevalence, incidence and severity of the diseases was recorded. Disease prevalence was clearly affected by agro-environmental factors. with no CBD recorded in the SE Mzimba EPA and low levels in the Phoka Hills EPA, but a mean of 95% of farms were affected in the Misuku Hills EPA over the 2 years. In contrast, coffee rust was found in all areas and was usually more prevalent than CBD. Cercospora leaf spot (Cercospora coffeicola) and Fusarium berry disease (Fusarium stilboides) were also recorded in most EPAs. Disease levels were higher in 1999 than in 1998, and the mean incidence of CBD per affected farm in 1999 was 40%. This ranged, however, from 10 to 56% depending on the EPA. The worst affected farm had 97% of bushes infected with CBD. There was also a difference in disease levels on the two most commonly-grown cultivars. The mean incidence of CBD for cv. Agaro was 23% but only 11% for cv. Geisha in 1998 compared to 59 and 19%, respectively in 1999. Management practices were correlated with levels of disease in 1999, and pruned or intercropped plantations had lower disease incidence. (C) 2001 Elsevier Science Ltd. All rights reserved.