PYRENOPHORA-TRITICI-REPENTIS AS A COMPONENT OF THE FUNGAL FLORA OF WINTER-WHEAT SEED IN NEW-YORK

Pyrenophora tritici-repentis incites tan spot, a common foliar disease of soft white winter wheat in New York. Since seedborne inoculum is s uspected of playing a role in the epidemiology of the disease, an asse ssment was made of the occurrence of P. tritici-repentis among the fun gal flora of soft white winter wheat seed in New York in 1990 and 1991 . The fungus was recovered from 54% of the seed lots in 1990 and from 36% of the seed lots in 1991, infecting an average of 2.1% and 0.6% of the seeds, respectively. Seed infection by fungal pathogens was gener ally low in 1991. Alternaria spp. were the fungi most commonly associa ted with soft white winter wheat seed in both years. Stagonospora nodo rum, Epicoccum nigrum, and various Fusarium spp. were also prevalent, especially in 1990. Mycelium of P. tritici-repentis was detected by cu lturing and light microscopy in all layers of the pericarp of the whea t seed, but not in the seed coat or in the embryo. Surface infestation of the seed by conidia and conidiophores was minimal.