Wheat is one of among major staple food crop in Ethiopia. However, several wheat stem rust diseases out break had been caused significant losses of crops in many parts of the country. This research was undertaken to quantify spatial distribution and intensity of Puccinia graminis f.sp.tritici in western and southwestern Ethiopia. The disease parameters were measured from 105 farmer’s fields of 6 districts in four zones. The survey was carried out by purposive multistage sampling methods depending on the importance of the crops at areas. Stem rust was prevalent and widely distributed in all study areas. Analysis of variance indicates fields, districts, and zones significant (p<0.01) by disease incidence and severity %. ANOVA of disease intensity with altitude, weed management, a wheat variety is grown and growth stage also significant at (p<0.01). Disease means prevalence ranged from 66.7%-92%in zones and the lowest and the highest being at Jimma and in Assosa zones, respectively. Mean % incidence was in the range of 3.7-47.9, the lowest and the highest being in Dedo and Begi districts in a given order, with the corresponding severities of 4.866.5%. The disease was severe in mid altitude with warmer weather conditions. Correlation analysis indicates, a significant (P<0.05) and positive association between crop growth stages and disease intensity, incidence (r=0.10) and severity(r=0.15) indicating that stem rust is more intense in the later wheat crop growth stages. Stepwise multiple regression in the current study indicates, the strongest predictor for disease severity was the growth stage with the highest β value which is 0.47 and with its highest shared; (0.455)2 = 20.1% and unique (0.429)2 = 18.4% contribution for disease severity. In conclusion, wheat stem rust disease was widely distributed and intense in wheat farms of the west and southwestern Ethiopia and the need to undertake regular monitoring across the study areas
