Association of biophysical and agronomic factors influencing yellow rust (Puccinia striformis f.sp. tritici) epidemic on bread wheat in the Southern Highlands of Ethiopia

Wheat yellow rust is the most economically important wheat disease in the Ethiopian highlands. This assessment was conducted to study the association of biophysical and agronomic factors on wheat yellow rust severity and incidence in the highlands of the Guji zone, south Ethiopia. A field survey was conducted in 15 kebeles in the Guji zone using a multi-stage sampling procedure. The mean of disease prevalence was 100% at Bore and Dama districts, whereas it was 92% at Ana Sora. The incidence and severity of wheat yellow rust were varied significantly ( P < 0.01) across districts and kebeles. Results of disease parameters were highly significantly correlated in different biophysical factors that aggravated the yellow rust. The highest disease incidence was noted at Bore (66.4%), followed by Dama (64.0%) and Ana Sora districts (47.0%). A similar trend was noted for disease severity with 58.4%, 54.4%, and 33.6% at three locations, respectively. The result of regression and correlation analysis showed that there were highly significantly different between biophysical and agronomic factors factors that influenced the severity and incidence of wheat yellow rust. The association of biophysical and agronomic factors, such as planting date, growth stage, crop rotation, tillage frequency, and weed infestation, significantly impact wheat yellow rust disease severity and incidence. Of these, altitude and varieties were the most aggravated on the yellow rust disease severity and incidence in the study areas. Thus, the study indicated that most of the wheat fields were extensively affected by yellow rust. This survey is pillar for environmentally safe and the most effective wheat yellow rust control strategies in South Ethiopia.