178217b0Nature1784526195607282172180028-0836195610.1038/178217b0ukNatureNatureNATUREnatureNature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public./nature/journal/v178/n4526issueJournal homeArchiveCurrent issueAdvance online publicationPrivacy policySubscribeNature Publishing GroupCurrent issue178217b0Control of Coffee Berry Disease in Kenya
AU  - BOCK, K. R.
AU  - RAYNER, R. W.Coffee Research Station, Ruiru, Kenya. March 14.A DISEASE of coffee berries, attributed to a form of Colletotrichum coffeanum Noack, was first described from West Rift areas of Kenya in 1922 1. It caused extensive losses and the abandonment of coffee cultivation on many estates, and although by 1939 selections of coffee which showed some degree of resistance had been made, direct attack with a considerable range of fungicides had led to little, if any, control of the disease. A detailed account of the disease and of investigations up to 1950 has been published2.Previous work1 had shown that disease symptoms could be reproduced by the inoculation of the pathogen into wounded or detached berries ; but the degree of pathogenicity was not established until symptoms were produced using spore inoculum without wounding3.
In 1951, the disease appeared for the first time in the East Rift coffee area, the higher-altitude zones being affected. As this area produces the greater proportion of the Kenya coffee crop, investigations on the disease received a considerable impetus. Further fungicide trials were carried out using Perenox, phenyl mercury, Fixtan, Tulisan and calcium sulphamate ; but no degree of control was observed.
Early in 1955, the effects of a wide range of fungicides were tested on an estate in the East Rift area. Fifteen treatments were compared using six replications of a balanced, incomplete block design with three plots per block. Each block consisted of one head of three multiple-stem trees, the trees selected having three equal heads each. In this way, individual tree variations in susceptibility and yield could be statistically controlled. The following fungicides were applied at monthly intervals during the long rains (March-May) and the short rains (November-December), giving a total of five applications ; Perenox, Karathane, Verdasan, Fermate, Zerlate, Dithane, Actidione, Captan, Glyox-alidine and calcium sulphamate. In addition, Perenox was applied at fourteen-day intervals throughout the season.
Only Perenox, applied at fortnightly intervals, and Verdasan gave an effective control of the disease. No control could be detected when Perenox was applied at the same frequency as Verdasan. As fortnightly fungicidal application is undesirable, Verdasan affords the best possibility of control as yet. In view of the earlier failure to obtain direct control of the disease with fungicides, the importance of these results is considerable.
Repeated calcium sulphamate treatments at 1, 3 and 6 per cent were all found to be highly phytotoxic although previously a single application at 1 per cent had not produced any adverse effects.
A laboratory technique for testing fungicides on detached berries has given results comparable with those of the field trials. Preliminary tests using Griseofulvin at a concentration of 880 p.p.m. have given results similar to Verdasan.
Further field trials are in progress.McDonald, , J., Trans. Brit. Mycol. Soc., 2, 145 (1926).Rayner, , R. W., East African Agric. J., 17, 130 (1952).Rayner, , R. W., Ann. Rep. Dept. Agric. Kenya, Pt. 2 (Invest.) (1952).