There are many fungicides and insecticides labeled for use in Iowa soybean. With partial funding from industry and soybean checkoff funds from the Iowa Soybean Association, we evaluated common foliar fungicides and insecticides at seven locations across Iowa in 2012 to determine yield response to an R3 (beginning pod set) application timing (Fig. 1).
Materials and Methods
The experimental design was a randomized complete block with four replications at each location. Details on variety and planting, application and harvest date are listed in Table 1. Treatments (Table 2) consisted of an untreated control, fungicides alone, insecticides alone, fungicides and insecticides in combination and pesticide application based on aphid scouting (IPM). In applicable treatments, fungicides and insecticides were applied at growth stage R3 (beginning pod) at all seven locations. Disease was assessed when soybeans were at the R6 growth stage (full seed set). Soybean aphid populations were observed between R3 and R6, but soybean aphid populations did not reach threshold at any of the seven locations. Total seed weight and moisture was measured, seed weight was adjusted to 13 percent and yield was calculated.
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