Effect of Fungicide on the Development of Wheat Stem Rust and Yield of Wheat Varieties in Highlands of Ethiopia

Stem rust caused by Puccinia graminis f.sp tritici Erik. & E. Henn. is a highly destructive disease of wheat (Triticum aestivum L.). The effects of fungicide application on stem rust (Puccinia graminis tritici) epidemics and yield of three bread wheat varieties varying in reaction to the disease were studied in two major wheat growing and stem rust prone districts (Agarfa and Sinana) of Bale, Ethiopia. Disease onset was late, generally after ear emergence, at both locations; but stem rust severity increased at high rates and terminal severity levels up to 81, 72 and 37% at Agarfa, and up to 37, 32 and 14% at Sinana were recorded on the varieties Sirbo, Maddawalabu and FH4-2-11, respectively. The rates of infection and AUDPC values of stem rust on the varieties were significantly (P<0.05) reduced by the fungicide sprays. The disease resulted in relative grain yield losses of up to 29% at Agarfa and 22% at Sinana on unsprayed plots. Thousand kernel weight reductions of up to 25.4% at Agarfa and 19.2% at Sinana were recorded. Generally, only the weekly fungicide application gave nearly complete control