Abstract:
Wheat is one of the most important cereal crops of Ethiopia.Stem rust (black rust) caused by
Puccinia graminis f.sp.tritici is one of the most important air borne diseases of wheat
(Triticum aestivum) in the high lands of Ethiopia, including North and South Gondar
administrative zones. The pathogen is capable to produce new physiological races that attack
resistant varieties and develop epidemic under favorable environmental conditions which
results in a serious yield loss. However, information on the status of stem rust distribution and
races in North and South Gondar zones is limited. Wheat stem rust damage samples were
collected in 2016 and 2017 in the North and South Gondar administrative zones of Wegera,
Debark, and Farta and Lay Gayint districts. Thus, this study was carried out to investigate the
distribution and intensity of wheat stem rust and to detect the virulence spectrum of P.
graminis f.sp. tritici. The survey result showed that out of the 95 wheat fields assessed in the
two zones, 70.91% were infected by the stem rust disease. The overall mean incidence and
severity of wheat stem rust in both zones was 4.76% and 3.31% respectively during 2016 main
cropping season and out of the 55 wheat fields assessed in the two administrative zones,
91.5% were infected by the stem rust disease. The overall mean incidence and severity of
wheat stem rust in both administrative zones was 49.59% and 23.41% in both zones during
2017 main cropping season respectively. The physiologic races of the rust fungus were
determined on seedlings of the standard wheat stem rust differentials following the
international system of nomenclature. One hundred fifty samples were analyzed in 2016 and
2017 cropping seasons which were collected from Wegera, Debark, Farta and Lay Gayint
districts of North and South Gondar administrative zones. From 95 samples analyzed in 2016
three races which included TKTTF, TTTTF and RRTTF were identified. Similarly three races
namely, TKTTF, TTTTF and TTRTF were identified from 55 stem rust samples analyzed in
2017. Race TKTTF (Digelu race) was predominant and widely distributed in all the zones with