Control of coffee berry disease*

Abstract

SUMMARYField experiments comparing six spraying programmes and two fungicides for control of coffee berry disease were carried out at three sites during 1968. These established that protection of the crop by sprays applied throughout the long rains (February–July) gave the best control and increased yields threefold. Early season spray programmes, which reduced the sporulating capacity of the pathogen in coffee twigs, but which ceased before the end of the rainy season, gave no disease control in the late crop (harvested October‐December) and yields were less than in unsprayed controls. All programmes which gave protection at the onset of the rains gave some disease control in the early crop (harvested June‐August). Captafol (‘Ortho‐Difolatan’ 80 WP) was better than a 50% copper formulation (‘Perenox’).Conditions suitable for infection, as determined from meteorological records, occurred frequently during both rainy seasons. Estimates of sporulating capacity and data from spore trappings showed that although inoculum from the bark might initiate an epidemic, subsequent disease progress was more dependent upon spores derived from diseased berries; these accounted for most of the inoculum dispersed during the greater part of the season. Removal of the early crop, which was very small, had no detectable effect on disease in the late crop.Although losses were greatest with early season spray programmes, these did nevertheless delay the onset of the epidemic. However, the subsequent rate of disease increase was greatest and ‘scab’ lesion formation least in these treatments. ‘Scab’ lesions were most abundant in those treatments which caused least delay; in unsprayed coffee, it appeared that early exposure to infection resulted in ‘scab’ lesion formation which subsequently retarded the rate of disease progress. Tree height was positively correlated with disease incidence, but there was little effect of tree aspect. Crop density had a small effect on disease incidence within branches.