IMPACT OF PLANTING BELL, A SOYBEAN CULTIVAR RESISTANT TO HETERODERA-GLYCINES, IN WISCONSIN

Although the soybean cyst nematode (SCN), Heterodera glycines, has bee n known to exist in Wisconsin for at least 14 years, relatively few gr owers sample for SCN or use host resistance as a means to manage this nematode. The benefit of planting the SCN-resistant cultivar Bell on a sandy soil in Wisconsin was evaluated in 1992 and 1993. A range of SC N population densities was achieved by planting 11 crops with varying degrees of susceptibility for 1 or 2 years before the evaluation. Aver aged over nematode population densities, yield of 'Bell' was 30 to 43% greater than that of the susceptible cultivars, 'Corsoy 79' and 'BSR 101'. Counts of cysts collected the fall preceding soybean were more p redictive of yield than counts taken at planting. Yields of all three cultivars were negatively related (P < 0.001) to cyst populations. Few er (P < 0.01) eggs were produced on 'Bell' than on the susceptible cul tivars. The annual (fall to fall) change in cyst population densities was dependent on initial nematode density for all cultivars in 1992 an d for the susceptible cultivars in 1993. Yield reductions induced by t he SCN under the conditions of this study indicate that planting a SCN -resistant cultivar in Wisconsin can be beneficial if any cysts are de tected.