Performance of Selected Insecticides Against Saltmarsh Caterpillar in Soybean 1, 2021

The performance of selected foliar insecticides treatments against saltmarsh caterpillar infestations in soybean was evaluated at the Delta Research and Extension Center (Washington County). Soybean seed (Asgrow 46X6) were planted on a Tunica clay soil on 21 May at a seeding rate of 117,612 seeds/acre. Plot size was four rows (40 in centers) by 40 ft. Treatments were replicated four times in a RCB design. Foliar insecticide treatments were applied on 11 Aug with a high-clearance sprayer with a compressed air spray system calibrated to deliver 10 gpa through TX-12 hollow cone nozzles (2/row) at 5 mph. Soybean looper densities were determined by sampling one of the center two rows with a 15-inch diameter sweep net. A sample consisted of 25 sweeps per plot. Plots were sampled at 2, 5, and 7 days after treatment (DAT). The same row in each plot was not sampled on consecutive sample dates. Data were subjected to ANOVA and means separated according to Fisher’s Protected Least Significant Difference.

All of the insecticide treatments, except Steward, reduced saltmarsh caterpillar numbers compared to the untreated check at 3 DAT (Table 1). At 5 DAT, all of the insecticide treatments, except Lannate and Warrior, reduced saltmarsh caterpillar numbers compared to the untreated check. All of the insecticide treatments, except Lannate, Warrior, and Warrior plus Acephate, reduced larval numbers compared to the untreated check at 7 DAT.¹

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