Detection Of Pathological Isolates Of Stem Rust From Selected Wheat Fields And Varieties’ Reactions In Tanzania

ABSTRACT

This study was conducted to determine status of wheat stem rust disease in Tanzania and how the available wheat varieties react to the prevailing isolates of this disease. The study aimed at identifying isolates groups and resistant varieties, and draw implications for farmers, research and extension. Wheat stem rust disease survey was conducted in twenty fields from Manyara, Mbeya, Iringa Kilimanjaro and Arusha regions. Of all the fields surveyed 60% were infected by stem rust disease with severity between 26 – 50%. Fifteen percent of fields were affected at 11 – 25% disease severity and 10% had 51 – 75%. The lowest disease severity of 5% was scored in Iringa region whilst in northern highlands none of the field was infected at a severity level of less than 15%. Seventeen isolates of Pucinia graminis f. sp. tritici collected from the selected regions were all virulent to Viri wheat variety. Isolates from Manyara and Arusha were more virulent followed by those from Kilimanjaro, Mbeya and Iringa. The most destructive isolate encountered in different regions caused various severity levels on Viri wheat variety with average severity of 37.5%. Most varieties (Mamba, Mbayuwayu, Selian, Juhudi, Azimio 87, Chiriku, and Riziki) under production were susceptible to wheat stem rust disease. Sifa variety response to wheat stem rust isolates both in the field and under controlled environment indicated an outstanding resistant to the most aggressive isolates and is thus recommended for disease management. Technology transfer is significantly important for farmers to get rid of using susceptible varieties e.g. Viri. Plant protection strategies such as crop rotation and weeding are not implemented accordingly in some areas; such cases need to be addressed as well to improve wheat production in Tanzania