Screening for resistance to Ascochyta blight in populations of Phaseolus coccineus L. and P. polyanthus Greenman

Abstract Ascochyta disease is a serious constraint of the cultivation of the common bean, Phaseolus vulgaris L., particularly in the Andean region. In this study, we describe the fungus, the plant symptoms caused by the disease, the ecological conditions which favour the outbreak, the regions where the disease prevails and some measures of control. No good level of resistance has been found in previous trials within the primary gene pool of P. vulgaris . In two highlands stations of Colombia, Popayan and Rionegro, we screened more than 200 populations of P. coccineus L. and P. polyanthus Greenm., two species cross-compatible with P. vulgaris . A very high level of resistance was observed in all the P. polyanthus populations and in some P. coccineus populations. This materials has been hybridized succesfully with some common bean varieties. More attention should now be devoted to the breeding of interspecific lines.