Distribution and Association of Common Bean Angular Leaf Spot (Phaeoisariopsis griseola) with Biophysical Factors in Southern and Southwestern Ethiopia
In Ethiopia, the average yield of common bean is low due to a wide range of factors. Angular leaf spot (ALS), caused by Phaeoisariopsis griseola, is one of the most destructive diseases in major bean growing areas of the country. Therefore, a field survey was conducted in four districts and two agricultural research centers to determine the distribution and importance of ALS intensity and its association with different biophysical factors in southern and southwestern parts of Ethiopia. In the survey, ALS was found prevalent in all common bean growing fields. However, mean incidence and severity varied among independent variables and variable classes. Mean incidence varied from 66.35% in Awassa Zuria district to 88.06% in Jimma Agricultural Research Center (JARC), whereas mean severity ranged from 81.14% in Bako Tibe district to 90.58% in Hawassa Agricultural Research Center (HARC). Higher mean incidence of 81.57% was obtained at altitude of >1718m.a.s.l than lower altitude class. The highest (86.56%) disease severity was obtained at pod filling stage compared to other
growth stages. The independent variables showed a variable association response to ALS disease intensity in logistic regression model. Variables like districts, cropping system, growth stage, sowing date and weed density were significantly (p ≤ 0.05) associated with disease incidence. Low mean disease incidence had high probability of association to Bako Tibe district, lower weed density and intercropping system. Similarly, low mean disease severity had high probability of association to Bolloso Sore district and lower altitudinal range. Findings of this study showed that ALS is a major constraint of common bean production, implying the need for proper intervention to improve available common bean varieties through careful weeding, intercropping practices and use of clean seed in the study areas and other agro-ecologies.