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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.

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