SEASONAL VARIATIONS IN SPORULATING CAPACITY OF FUNGUS CAUSING COFFEE BERRY DISEASE

Assessments of the sporulating capacity of Colletotrichum coffeanum Noack in coffee branches (defined as the number of conidia produced per cm2per hour under optimum conditions) have been made for 4 years on a number of different sites in Kenya. An annual rhythm is evident which is essentially similar on all sites and for all years. Early‐season and late‐season peaks are separated by a mid‐season trough. The change in sporulating capacity at any time is negatively correlated with wetness in the immediately preceding period, and daily rainfall can be used as a measure of wetness. The position of the peaks and their duration is defined by the timing of the onset and the duration of the monsoon rains, and is, therefore, subject to considerable variation. It is suggested that the correct timing of control sprays might be related to the form of the annual curve of sporulating capacity, and be predictable from rainfall records. Copyright © 1969, Wiley Blackwell. All rights reserved