Distribution and Pathogen Variability of Wheat Stem Rust (Puccinia Graminis f. sp. Tritici) in North Shewa of Ethiopia

Wheat stem rust (Puccinia graminis f. sp. tritici) is the most destructive and devastating foliar disease of wheat, which causes considerable yield losses. The objective of this study was to assess the importance, distribution, and intensity (prevalence, incidence, and severity) of wheat stem rust disease, and to determine their associations with biophysical factors, pathogenic variability, and virulence spectrum in the North Shewa zone of Ethiopia. In 11 districts, 64 fields were assessed diagonally using 1 m × 1 m quadrats at five random spots. According to the survey results, 87.5% of the fields were infected with wheat stem rust. The highest mean disease incidence (95%) and severity (68.33%) were noted at Minjar Shenkora, whereas the lowest incidence (20%) and severity (13.69%) were at Basona Werana and Moretna Jiru, respectively. Almost all biophysical factors were significantly associated with wheat stem rust epidemics (P < 0.001). Especially, fungicide application plays a significant role in disease incidence and severity. From the 31 monopustules/isolates, six races (TKTTF, TTTTF, TTRTF, TKKTF, TTKTT and TTKTF) were identified; race TKKTF was the predominant one. Races TTKTT exhibited virulence to 95% of the stem rust resistance genes. Wheat stem rust was a severe disease of wheat in the zones. It may cause significant economic losses if susceptible local cultivars, Hidasse and Danda’a, were continued to be grown in the area. A national survey is recommended to develop a disease distribution map and generate a clear picture of the disease status for early warning and disease deployment. Implementing integrated disease management practices and creating or promoting resistant wheat varieties could be vital in mitigating the impact of the stem rust pathogen and other rust diseases of wheat. Developing and deploying stem rust-resistant wheat varieties through collaboration between breeders and pathologists is critical to protect smallholder farmers.