Abstract

Common bacterial blight (CBB), caused by Xanthomonas axonopodis pv. phaseoli Smith (Xap) and Xanthomonas axonopodis pv. phaseoli var. fuscan Burkholder (Xapf) is the most serious biotic constraint of common bean (Phaseolus vulgaris L.) production. Variables temperature and moisture are dominant climate factors that affect common bean growth as well as the development of CBB epidemics. Two sets of experiments were conducted in the Plant Pathology Laboratory of Haramaya University) to assess the effect of temperature and moisture on the resistance level of common bean in 2014 and 2015. In the first experiment, two common bean varieties (Gofta and Mexican 142) were inoculated with two bacterial strains (Xap and Xapf) and a control were incubated at four temperature levels (28°C, 30°C, 32°C and 34°C) in growth chambers. In the second experiment, three-soil moisture levels (100%, 75% and 50%) were employed to that of experiment one. The treatment combinations were arranged in factorial completely randomized design (CRD) in the growth chambers for both series of experiments. The disease rating was significantly (P