Evaluation of fungicides for the control of coffee berry disease in Kenya

Some sixty fungicides were tested in the laboratory for ability to ( a ) depress sporulation of Colletotrichum coffeanum on the maturing bark of coffee shoots and ( b ) inhibit spore germination. On the basis of these tests over twenty products were selected for testing in the field during 1968-70. Nine of these (50 % copper formulations, Ortho-Difolatan, Daconil, Benlate, Topsin, Top-sin M, Tecto 60, Delan and Du-Ter) could be recommended for control of coffee berry disease (CBD) in Kenya.
Field evaluation of fungicides is complicated by multiple flowering which creates a succession of overlapping crops, and by high variability in cropping potential which is often aggravated by normal pruning practices; in some circumstances other diseases and pests may also be a complicating factor. As a result, yield, which should be the most sensitive measure of CBD control, is at times even less satisfactory than disease estimates based on a small sample of the developing crop. Disease incidence in the ripe crop, which is easy to measure, is unfortunately not always well correlated with disease and crop loss earlier in the season. Consequently, critical assessment of fungicide performance requires estimates of both disease progress and crop loss.
Consideration of fungicide performance indicates that physical characteristics, particularly persistence and capacity for redistribution, are especially important for effective control of CBD.