Accepted 6th January, 2019
Wheat is one of the important cereal crops of Ethiopia. It ranks third in land coverage and total production after tef and maize and in productivity after maize and sorghum. Hararghe highlands are also considered to be suitable for wheat cultivation in the country. However, the production of wheat in this region is threatened by the stem rust disease. This study was conducted with the following objectives: to determine distribution, incidence and severity of wheat stem rust Puccinia graminis f.sp. tritici in Hararghe highlands. Field surveys were carried out in eight districts of east and west Haraghe zones. A total of 200 fields were surveyed. Stem rust occurred in 80% and 74% of the fields surveyed in East and West Hararghe zones, respectively. Its incidence was 38.32% and 30.43% in East and West Hararghe areas, respectively. There was significance difference among the zones, districts and peasant associations (P< 0.05). The highest mean severity (35.36%) was recorded in Meta followed by Anchar (12.4%) and Melkabalo (12.00%). The disease severity was highly significanct among the zones, districts and peasant associations (P< 0.05). All the varieties grown in the two zones were attacked by the disease in one area or the other, though the degree of incidence and severity varied. Varieties such as Kubsa, Wabe, Abola and Pavon76 were found to be severely affected in East and West Hararghe zones. During the main crop season, the disease was more severe in Meta district and Anchar district of East and West Hararghe zones, respectively. The wheat rust trap nursery planted at Haramaya indicated maximum severity of 100%. But, in Hirna it indicated maximum severity of 40%. Differential lines such as PBW343, BARLETA BENVENUTO, CNS SR32AS, W2691SR9B, W2691SR10 and SWSR22T.B, BT/WLD and H44 DERIV have high infection at Haramaya whereas they had less infection at Hirna. This indicated that the disease intensity at Haramaya was very high than Hirna. Inoculation of quick-test in the greenhouse indicates susceptible reaction with bulked isolates of Puccinia graminis f. sp. tritici collected from East and West Hararghe zones.
Keywords: Stem rust, incidence, severity, Puccinia graminis f. sp. tritici, East and West Hararghe