Analysis of Climate Variability Effects on Wheat Stem Rust ( Puccinia graminis f.sp tritici ) Epidemics in Bale and Arsi Zones of Oromia Regional State, Ethiopia

Stem rust caused by Puccinia graminis f.sp tritici , is the most destructive disease of wheat in the world. Bale and Arsi zones are conducive for stem rust epidemics. The study was conducted in 2013 to assess and model the effect of climate variability on wheat stem rust epidemics. The meteorological and disease data for the year 2004 to 2013 of Sinana and Kulumsa were obtained from the respective research centers and were analyzed. Four bread wheat cultivars, namely Kubsa, Madawalabu, Sofumer and Tusie were included in the study. The present study showed that stem rust epidemics was higher at kulumsa than at Sinana over the last 10 years. The increased stem rust severity at Sinana and Kulumsa were due to the total seasonal rainfall increase during wheat growing seasons. A reduction in stem rust severity was manifested at Sinana and kulumsa as seasonal mean minimum temperature increased, whereas a reduction in stem rust severity occurred at Kulumsa as the seasonal average relative humidity increased. The total seasonal rainfall had positive effect on the development of wheat stem rust, while the seasonal mean minimum temperature and seasonal average relative humidity significantly affected the development of wheat stem rust in the field.