Detached berries response to coffee berry disease (Colletotrichum kahawae) of F1 hybrid genotypes developed from Ethiopian accessions of Arabica coffee

Arabica Coffee (Coffea arabica L.) is a cash crop that supports the livelihoods of many Tanzanians, but its productivity is limited by various factors, including Coffee Berry Disease (CBD) caused by Colletotrichum kahawae. CBD can lead to up to 90% coffee yield losses in Tanzania. There are different control measures for CBD, but the use of resistant cultivars has been mentioned to be a more sustainable method than the use of copper-based fungicides. This study was carried out to determine the level of CBD resistance within the F1 population and to identify top-performing hybrids. The experiment was conducted using a split-plot design under a Randomized Complete Block Design with three replications in the Pathology laboratory at the Tanzania Coffee Research Institute (TaCRI). Detached green berries of eight coffee genotypes were inoculated with three different isolates of C. kahawae (2006/14, 2019/16, and 2019/11). Disease severity on detached berries was assessed at 7, 11, and 15 days after inoculation. The results revealed significant variation (P ≤ 0.05) among the coffee genotypes. Two genotypes, F90/64/4660 x KP423 and F89/64/4660 x KP423, showed a very high level of resistance with absolutely no disease development, equivalent to the resistant check KP423. Genotypes F24/64/902 x KP423 and F54/64/2049 showed moderate susceptibility, while the susceptible check KP423 developed typical CBD symptoms. The interaction between genotypes and C. kahawae isolates revealed significant differences in the number and size of lesions formed. This study verified the resistance of the tested F1 hybrid genotypes, which have the potential to be exploited for CBD-resistant varieties in Tanzania.   Key words: Arabica coffee, coffee genotypes, coffee berry disease, Colletotrichum kahawae Isolates.