Distribution of Chickpea (Cicer arietinum L.) Ascochyta blight (Didymella rabiei) and analyses of factors affecting disease epidemics in Central Ethiopia

Abstract

Ascochyta blight (caused by Didymella rabiei) is one of the most important diseases affecting chickpea production and productivity. The distribution, incidence and severity of the disease, and the association of agronomic practices and environmental factors on the intensity of the disease mainly remained undermined. Chickpea field surveys were conducted in two main chickpea growing regions of central Ethiopia during the 2020 and 2021 main cropping seasons to determine the distribution and importance of Ascochyta blight and analyse its association with biophysical factors. A total of 366 chickpea fields were surveyed in five zones, and 76.6% of the fields were infected with Ascochyta blight. The results revealed that the overall mean prevalence and incidence of the disease ranged from 46.66 to 100%. Ascochyta blight in the infected fields had a mean severity index of 40.17%. The mean disease incidence was higher in fields at altitudes below 2129 m.a.s.l (39.2%) than the mean incidence of fields at higher altitudes. Using logistic regression analysis, the independent variables—zone, altitude, cropping season, seed source, cultivar type, variety, planting pattern, and plant density—were shown to have significant effects on the severity index (P < 0.001). High weed density, growth stage, planting time, crop rotation, Fusarium wilt, pod borer, aphid spp., and dry root rot were also significantly associated (P < 0.05) with Ascochyta blight epidemics. The highest severity (SI = 60.3%) was obtained in Arsi Zone, and the lowest in South West Shewa Zone (SI = 32.1%). The results of this survey indicate that planting chickpea in the middle of the main rainy season, proper weed management, planting improved varieties, and crop rotation should be practiced to reduce the negative impact of the disease until effective resistant chickpea varieties are developed. Furthermore, it is recommended that effective and feasible integrated management options need to be developed against the disease to boost the production and productivity of the crop.