|Effects of Clariva seed treatment on soybean cyst nematode (Heterodera glycines) population densities and soybean yields in Iowa in 2014|
G. L. TYLKA (1), C. C. Marett (1), A. E. Robertson (1), M. Serrano (1), T. A. Mueller (2). (1) Iowa State University, Ames, IA, U.S.A.; (2) Iowa Soybean Association, Ankeny, IA, U.S.A.
Twenty-four field experiments were conducted in Iowa in 2014 to assess the effects of Clariva seed treatment (active ingredient <i>Pasteuria nishizawae</i>) on <i>Heterodera glycines</i> reproduction and soybean yields. Nine small-plot experiments with 4-row-wide by 5.2-meter-long plots were planted with seed of the moderately resistant soybean variety Asgrow AG2433 treated with either Clariva Complete Beans or CruiserMaxx Advanced plus Vibrance. The seed-treatment packages varied only in the presence or absence of Clariva. Treatments were replicated 12 times in each experiment. Fifteen strip-trial experiments consisted of 12- to 24-row-wide by 305- to 457-meter-long strips of the same two seed-treatment packages. Variety AG2433 was used in eight strip trials; other resistant soybean varieties were used in seven trials. All but two trials had five or more replications. Soil samples were collected at planting and harvest to assess <i>H. glycines</i> population densities in each small plot and from sampling points in many of the strip trials. Reductions (P=0.03 to 0.15) in season-long <i>H. glycines</i> reproduction were associated with Clariva in three of the nine small-plot experiments. Yields were determined from each plot and strip in every experiment. Mean yields ranged from 3.14 to 4.87 metric tons per hectare in small-plot experiments and from 2.47 to 6.16 metric tons per hectare in strip-trial experiments. Yields of treatments were different (P=0.11 to 0.20) in eight of 24 experiments.