Sources of resistance to powdery mildew in barley.

Abstract

Race-specific resistance of 164 barley varieties to Scandinavian cultures of powdery mildew is reported. In total, reaction is given against 94 cultures, involving 73 races of the pathogen. All the varieties have, however, not been included in all tests. Most of the material was earlier known to have mildew resistance, and only a few new sources are reported. Resistance to all Scandinavian cultures tested was obtained in more than 30 varieties, including spontaneous material, mainly originating from the Indian peninsula, Balkans and Turkey as well as induced mutants, all with resistance at the m1-o locus. Previously completely resistant varieties, such as Monte Cristo, Balouchistan, Grandpa, Hashiarpur, I 5, Lyallpur BS, and Triple Awn Lemma, were recorded susceptible in Sweden for the first time in 1973. Races virulent on Lyallpur 3645 and related varieties, such as Gopal, Lyallpur 2, Lyallpur 3647, Mian wali, and Mut. 5455, were isolated already in 1972. The extended information about the spectrum of resistance indicate the presence of more than one gene for mildew reaction in several varieties. Available data about the mildew resistance and its genetical background is summarized separately for each variety concerned. Information is further given about recently identified races of barley powdery mildew.