Variability of Common Bean Pathogens Angular Leaf Spot Caused by Phaeoisariopsis Gresiola (Sacc.) and Anthracnose Caused by Colletotrichum Lindemuthianum Isolates in Southern Ethiopia

Abstract

Angular leaf spot caused by Phaeoisariopsis gresiola (Sacc.), and Anthracnose caused by Colletotrichum lindemuthianum are important fungal pathogens which limits the production and productivity of common bean in the world as well as in East Africa. Common bean breeding for resistant cultivars against these diseases are more difficult because of the existence of variability and emergence of new pathogen races of these pathogens and consequences into continuous breakdown of resistance gene of the crop. Thus, recognizing races of each region pathotype is essential before staring common bean breeding resistant program. Field experiment was carried out at Hawassa, Dilla and Halaba under field condition and in the   green house during 2014 -2015 cropping season. Twelve CIAT common bean differentials cultivars were used for each pathogen to discover the race variability and its distribution in the region. Of the tested cultivars Bolon Bayq, BAT 332, and Conell 49242) were showed immune reaction to Southern Ethiopia ALS isolates. Differential Trepador and Mexico 154 showed only at Hawasa and Dilla location, and showed resistant disease reaction with mean disease score (2). The remaining differentials were showed from moderately resistant to susceptible disease reaction. Similarly for Anthracnose isolates, out of the tested differentials 66.7%, were not infected by the pathogen in both years. This preliminary result indicated the presence of variable isolates for two pathogens and resistant differential cultivar against Southern Ethiopian isolate. Therefore breeders should focus in developing common bean varieties that could resist the recorded races that attacking tested differentials in the region. The differentials those were not attacked by Southern Ethiopia isolate can be used as source of resistance to be used in the breeding program. In addition further study is needed through collecting pathogens from different common bean production area in the region and so that using molecular supported job for race identification.

Keywords: ALS, Anthracnose, common bean, differential, isolate, resistant