SURVIVAL OF WHEAT STREAK MOSAIC-VIRUS IN GRASS HOSTS IN KANSAS FROM WHEAT HARVEST TO FALL WHEAT EMERGENCE

Field samples of annual and perennial grasses were tested to determine which can be alternate hosts to wheat streak mosaic virus (WSMV) and can survive and sustain the virus from wheat harvest to fall wheat emergence in Kansas. Sites sampled included Conservation Reserve Program (CRP) hectares, government set-aside fields, wheat stubble fields, and waterways, Samples were collected in August of 1988 and at four approximately monthly intervals in 1989 and were tested for the virus by indirect ELISA. None of the perennial grasses sampled were infected, but five annual grass species-Setaria viridis, S. faberi, Eriochloa contracta, Echinochloa crusgalli, and Panicum capillare-plus volunteer wheat were infected throughout this period. This is the first report of S. faberi and E. contracta as hosts of WSMV. WSMV was detected in 24.1% of the samples of susceptible grass species in 1988 and 27.5% in 1989. Grasses susceptible to WSMV are abundant over much of Kansas, including in CRP fields, and infected plants could serve as an inoculum source for infection in fall-seeded wheat.