Response of F1 arabica coffee genotypes descending from disease resistant Ethiopian accessions to coffee berry disease

Abstract

Coffee is one of Tanzania’s primary agricultural export commodities but is seriously constrained by Colletotrichum kahawae which causes significant yield losses in Arabica coffee during high infection seasons. Using resistant varieties rather than chemical fungicides, which are costly and cause environmental pollution, is a more sustainable approach to controlling the disease. Several F1 hybrid genotypes developed from Ethiopian accessions of Arabica coffee of known Coffee berry disease (CBD) resistance were evaluated under CBD pressure to observe acquired resistance. Eight Arabica coffee genotypes were inoculated with three types of CBD pathogen isolates. Results revealed high resistance on two F1 genotypes (F90/64/4660 x KP423 and F89/64/4660 x KP423) with no infection to all C. kahawae isolates. Two Genotypes (F45/64/2049 x KP423 and F24/64/902 x KP423) revealed resistance moderately by scoring less than 50% infected berries, while F45/64/2061 x KP423 and F24/64/886 x KP423 demonstrated moderate susceptibility. The F1 genotypes with less infection are to be included in the breeding program to develop resistant varieties. Pathogenicity of three C. kahawae isolates obtained from different coffee growing areas in Tanzania was also observed for their effects on the tested genotypes.  Isolate 2006/14 from Kibosho – Kombo was more aggressive in terms of infected berries, followed by isolate 2019/16 from Ugano-Mbinga.  Isolates found to be more aggressive are potential for screening resistance to develop coffee berry disease varieties in Tanzania.