Surveying virulence of the causal agent of wheat stripe rust (Puccinia striiformis f. sp. tritici) and determining reaction of commercial wheat cultivars over the past decade in Fars, Iran

Annual survey for monitoring of reaction of commercial wheat cultivars to stripe rust disease is very important after their introduction and extensive cultivation. The host materials surveyed included the standard differential cultivars for stripe rust along with 24 and three respectively commercial bread and durum wheat cultivars. This study was accomplished in selected wheat fields of six regions of Fars province including Zarghan, Marvdashat, Fassa, Mammassani, Darab and Eghlid during 2003- 2005 and in two stripe rust nurseries in Zarghan and Mammassani during 2003- 2013. The results showed that the resistance of 12 cultivars including Chamran, Shirodi, Shiraz, Darab 2, Falat, Star, kavir, Zarin, Shahriar, Alvand, Alemot and Bahar was overcome by stripe rust during or before the last decade. Yavarous and several recently introduced cultivars including Zareh, Mihan, Siravan, Chamran 2, Ophogh, Behrang and Shabrang have conferred moderately to intermediate resistance reaction to the disease. The cultivars Sivand, Parsi, Pishgham, Marvdasht and Aflak showed a range of moderately resistance to moderately susceptible reaction. The response of Pishtaz varied from moderately susceptible to resistance. Nicknejad has shown to have high level of resistance since its long time introduction. Decrease or changes in the resistance of some of the cultivars can be attributed to changes in stripe rust races, weather conditions and environmental factors. In this regard among the differential cultivars, virulence was almost present for Yr2, Yr6, Yr7, Yr9, Yr17, Yr25, Yr26, Yr27, YrA and YrSU. Current research indicates that annual survey on responses of commercial wheat cultivars to stripe rust together with monitoring of pathogen virulence factors in Fars province are very necessary. These information not only can effectively aid in giving on-time warning to replace susceptible cultivars and to use effective control measures to reduce the loss of the disease, but also can play an important role in short and long time wheat breeding programs.