Methods for early evaluation for resistance to bacterial blight of coffee

Abstract

Bacterial Blight of Coffee (BBC) caused by Pseudomonas syringae pv garcae has become of major concern in Kenya due to its increasing incidence and severity. For decades, the disease was confined within and to the west of the Great Rift Valley, but recently it has spread to reach other coffee growing areas. In order to minimize the chemical input in its management, which apart from polluting the environment have high cost implications, development of resistant/tolerant cultivars is highly recommended. This study aimed at developing an effective method(s) for early evaluation of resistance to BBC and to use the method(s) to evaluate the reaction of selected coffee genotypes to different isolates of P. syringae pv garcae. Three isolates from different coffee growing areas in Kenya were used to inoculate thirteen coffee genotypes using injection and cut methods. The two inoculation methods were found to be effective and can be recommended with slight modifications. However, it was not possible to clearly authenticate the reaction of the different genotypes to BBC since the genotypes responded differently to different isolates and inoculation methods.