Reaction of Some Coffea arabica Genotypes to Strains of Colletotrichum kahawae, the Cause of Coffee Berry Disease

Pathogenicit) tcst~ \\ere performed 011 I I genotypes of Co//lʹa amhito lIsing s in£lc·isola tc slIspensions of Col/(ʹ /0Iri(ʹ/1II111 kallllllʹlI(, Ob t ~liI1cd from 90 l11o noconid ial isolcHLʹ~. The objccli\ʹc ofʹ this study was 10 estima te the proportion of pathogenic variation corresponding LO diflʹerem:es in aggres~ivencss and viru lence (races). A large 1);ʹlrt of the variation in the pathogen population was due to aggre$sivcncs~ . Th~ diOʹercnlial effects were laO ~ Jl1all to suggest conclusively that races exist. This paper disClIS: o,CS the possible causes for the ob:-,crved ~111:.t 1l differemial interaction and suggests breeding stra lcgi c~ thaI not ani) prevent possihle actapwlion of the pathogen to resistant variclic!o! but also limit v,uialioll IʹDIʹ resistance due to dincrencc~ in aggressiveness or the pathogen