8 NONHOST WEED SPECIES OF HETERODERA-GLYCINES IN IOWA

The ability of the soybean cyst nematode (Heterodera glycines) to repr oduce on eight weed species commonly occurring in Iowa was evaluated i n greenhouse and field microplot experiments. Population densities of the nematode increased on H. glycines-susceptible soybean but not on H . glycines-resistant soybean, Canada thistle, cocklebur, eastern black nightshade, giant foxtail, lambsquarters, redroot pigweed, velvetleaf , and wild sunflower. All of the weeds evaluated were nonhosts of this H. glycines race 3 population.