Assessment of Sorghum Anthracnose Disease Severity and Its Relationship with Biophysical Factors in South-Western Sorghum-Producing Regions of Ethiopia

Ethiopia is the second-largest producer of sorghum (Sorghum bicolor (L.) Moench) in Africa. Despite this production potential, yields and production levels remain low due to various challenges in the agricultural sector. One key fungal disease affecting sorghum is anthracnose, caused by Colletotrichum sublineolum, which significantly reduces grain yield. This study aimed to evaluate the severity of anthracnose in sorghum fields and its relationship with biophysical factors. During the main cropping seasons from October to November, 350 sorghum fields (187 in 2020 and 163 in 2021) across three regional states were sampled at early to stiff dough stages. Infected leaves were collected, and related factors were analyzed. Results showed a 100% prevalence of sorghum anthracnose in Ethiopia's western and southwestern regions. Incidence rates ranged from 46.15% to 100% in Assossa, 55.5% to 100% in Jimma, 75% to 84.62% in Illubabor, 78.5% to 100% in East Wollega, and 85.7% to 100% in Gambella, with average incidences of 83.78%, 85.81%, 78.10%, 78.57%, and 91.79.70%, respectively. Severity levels were particularly high in Jimma, Assossa, Agnuwak, Illubabor, and East Wollega, with mean severities of 35.25%, 34.5%, 28.97%, 28.32%, and 27.60%, respectively. The study shows that effective weed management, crop rotation, proper fertilizer use, sowing timing, disease-free seed selection, and favorable weather conditions directly influence the development of sorghum anthracnose. Therefore, to reduce the impact of this disease on sorghum production, implementing disease management strategies and policies to support farmers in the region is essential.