Stem Rust (Puccinia graminis f.sp tritici) Management in Wheat through Fungicide Spray Frequencies in Central Ethiopia

Among various wheat diseases, stem rust caused by Puccinia graminis f. sp. Tritici is the most striking, contributing to large yield losses in Ethiopia. The effect of fungicide spray frequency on yield components of bread wheat was studied under natural infection conditions at Mareko and Dalocha during 2021 growing season. Two different fungicides, namely, Nativo SC 300 (trifloxystrobin 100 g/l + tebuconazole 200 g/l) at 0.75 l/ha and Tilt® 250EC (propiconazole) at 0.5 l/ha, were compared in field at three spraying frequencies. Experiment was in a randomized complete block design with three replications. Unsprayed controls were also included for comparison. The disease resulted in relative grain loss up to 53.5% at Dalocha and 41.9% at Mareko in control plots. However, terminal rust severity, average coefficient of infection and AUDPC values were significantly (p<0.05) reduced due to frequent fungicide application. Compared with those the untreated plots, thousand kernel weight and grain yield increased (p ≤ 0.05) in fungicide-treated plots. Moreover, Nativo SC 300 provided the greatest increase in yield and was found effective in decreasing stem rust across both locations. Significant negative correlations were observed between TRS, ACI and AUDPC and between grain yield, kernel per spike and TKW, with correlation coefficients ranging from r=-0.85** to r=-0.33**. Cost-benefit analysis revealed, the combined use of Nativo SC 300 three times at ten-day intervals provides the greatest net benefit and is the best management strategy.