1987 Volume 53 Issue 4 Pages 470-477
Physiologic specialization of Erysiphe graminis f. sp. tritici collected from fields in Japan during 1962, 1967 and 1984-1986 was examined by detached leaf culture method. Seven wheat cultivars carrying a single gene for resistance, Axminster×Cc8, Ulka×Cc8, Asosan×Cc8, Chul×Cc8, Khapli×Cc8, Hope and Sapporo-haru-komugi were used as basic differentials, and twenty races were identified. Taking the distribution of races in Europe and also the breeding program of resistant cultivars into consideration, cultivars, Normandie, Halle Stamm 13471, C.I. 12633, Weihenstephaner M1, Arthur, Vernal, 0224/52 and Transec were used as additional differentials. However, all additional differentials were highly or moderately resistant to all races found in Japan. Chul×Cc8 (resistance gene: Pm3b) was resistant to all races identified in Hokkaido region, and was susceptible to all races in Chugoku region. It was noted that all cultivars in basic differentials were susceptible to some races found in Japan. Evidences obtained in this study indicate the guideline for breeding program of resistant wheat cultivars against powdery mildew disease. Namely, a major gene for resistance should be used in combination with other major gene (s) especially with that of foreign cultivars or wild relatives, in addition to the other trait responsible for so-called quantitative resistance known as slow-mildewing or durable resistance.