Insecticide Efficacy Against Grasshoppers on Soybean, 2018

This is the authors' abstract. We don't add key points for this paper.

The objective of this experiment was to evaluate the efficacy of insecticides for control of grasshoppers on soybean. Ag Venture ‘AV38E8LL’ soybean was planted in a narrow field bordered by woods and field corn on 11 May 2018 at the University of Delaware Carvel Research and Education Center in Georgetown, DE. A large number of grasshoppers were observed in the field during September. Plots consisted of 20 rows on 15 inch centers, 100 ft long and were arranged in a randomized complete block design with four treatments and three replicates. Each treatment was separated by 6 ft and each replicate was separated by 15 ft. Plots were treated on 22 Sept with a Crop Care 25’ side mount high pressure sprayer fitted with Tx80015VK nozzles delivering 30 gpa at 250 psi. Plots were sampled 1 day before treatment and 2, 9, and 13 days after treatment (DAT). Sampling consisted of 25 sweeps with a 15-inch diameter sweep net and visual inspection of two rows down the entire length of the plot for a total of 200 row-ft per plot. Data were analyzed with analysis of variance (ANOVA); Tukey–Kramer HSD was used for means separation. Sweep net samples indicated that a smaller grasshopper population may have been present in Sniper-treated plots prior to treatment. However, there were no differences among plots when sampled visually. Cool cloudy conditions 2 DAT and 13 DAT may have affected visual grasshopper observations. At 2 DAT all of the insecticide treatments, except Prevathon, significantly reduced the number of grasshoppers captured using sweepnet sampling compared with the untreated check (Table 1). At 9 DAT all of insecticide treatments significantly reduced numbers of grasshoppers captured using sweepnet sampling compared with the untreated check. There were no significant differences among treatments for grasshopper numbers at 13 DAT (Table 1). With visual sampling, all of the insecticide treatments significantly reduced grasshopper numbers at 2 and 9 DAT. No significant differences among treatments were observed at 13 DAT (Table 2). No phytotoxicity was observed. Means in the same column followed by the same letter are not significantly different (Tukey–Kramer HSD; P > 0.05). aMSO included at 1% v/v. Means in the same column followed by the same letter are not significantly different (Tukey–Kramer HSD; P > 0.05). aMSO included at 1% v/v. Means in the same column followed by the same letter are not significantly different (Tukey–Kramer HSD; P > 0.05). aMSO included at 1% v/v. Means in the same column followed by the same letter are not significantly different (Tukey–Kramer HSD; P > 0.05). aMSO included at 1% v/v. This research was supported in part by industry gifts of product.