Abstract

Wheat stem and yellow rusts which are respectively, caused by Puccinia graminis f.sp tritici and Puccinia striiformis f.sp. tritici, are among the most devastating diseases of wheat in Ethiopia. The use of fungicides is among the most important wheat rusts management strategy in wheat production and rust hot spot areas. The field experiment was conducted to evaluate the efficacy of some selected fungicides (Azoxystrobin + Cyproconazole, Pyraclostrobin + epoxiconazole, Fenpicoxamid + Pyraclostrobin, Fenpicoxamid + Hexaconazole, and Propiconazole) against wheat rusts in six major wheat growing locations and rust hot-spot areas of the West and Southwest Shewa zones of Ethiopia during the 2020/21 main growing season. The two most susceptible bread wheat varieties, Hidase and Kubsa, were used as test crop respectively, for stem and yellow rusts. The result revealed that significantly (P ≤ 0.05) the lowest yellow and stem rusts incidences were recorded from plots treated with propiconazole on Kubsa (3.8 and 1.3%) and Hidase (0 and 1.7%) varieties, respectively. Similarly, significantly (P ≤ 0.05) the lowest yellow (3.8 and 0.0%) and stem (1.3 and 1.7) rusts severity were also noted from plots treated with propiconazole, respectively, on Kubsa and Hidase varieties. Significantly, the highest yields of 5.7 t ha^-1 from Hidase and 4.6 t ha^-1 from Kubsa varieties were also observed from plots sprayed with propiconazole as compared to other treatments. Three fungicides used in this study namely propiconazole, fenpicoxamid + hexaconazole, and fenpicoxamid + pyraclostrobin, efficiently controlled the two rusts. From this study, it is concluded that twice spraying of propiconazole or either of these fungicides at a seven-day interval is recommended under high disease pressure conditions for both diseases.

Key words: Bread wheat, incidence, severity, stem rust, yellow rust.