Physiologic Races Of Tilletia Laevis In Khorasan

Common bunt (Tilletia laevis) isolates, were collected from naturally infected wheat spikes (1560 samples) in the wheat growing areas of Khorasan province, during 1997. Seeds of three sets of spring and winter wheat differentials, containing known resistance Bt genes were inoculated with teliospores obtained from twenty single head selections of these samples (each spike = one isolate). Two local susceptible cultivars Sardari and Roshan were also included as local checks. The experiments were carried out under natural conditions. In the field, artificially inoculated seeds of each set of differentials were sown in the depth of 4cm at two lines one meter long. In pot tests, 8-10 inoculated seeds were planted in each pot and 6 pots were allocated to each differential cultivar. Based on the resistance or susceptibility reactions of differential cultivars to 20 samples of T. laevis, four races L1, L3, L8 and L20, were identified. These races are reported for the first time from Khorasan province. Race L8 is new for Iran, and race L20 has not been reported anywhere else.