Differential seed infection of wheat cultivars by Stagonospora nodorum

Seed of soft white winter wheat collected from New York regional cultivar t rials in 1995 and 1996 were assayed on an agar medium selective for Stagono spora nodorum. Incidence of seed infection varied with production environme nt. Relative incidence of seed infection differed significantly among culti vars and was consistent across environments. The flag leaves and ears of 12 cultivars were inoculated quantitatively at flowering in a glasshouse. Cul tivars did not differ significantly in disease on the flag leaves. Incidenc e of seed infection for all cultivars was above 60%, but was significantly lower in Delaware and Houser than in other cultivars. Results confirm that wheat cultivars differ in their relative susceptibility to seed infection b y S. nodorum. Resistance in wheat to seed infection by S. nodorum may be a useful mechanism for reducing initial inoculum in areas where infected seed is considered the primary inoculum source for Stagonospora nodorum blotch.