Evaluation of Foliar Insecticides for the Control of Lepidopteran Larvae in Tomatoes, 2016

The objective of this experiment was to assess the efficacy of foliar insecticides for the control of lepidopteran larvae in tomatoes. The experiment was conducted at the Virginia Tech Eastern Shore Agricultural and Research Center in Painter, VA and consisted of seven treatments arranged in an RCB design with four replicates. ‘BHN 602’ tomatoes were transplanted on 27 Jul 2016. Plots were one-row wide and 20-ft (6.1 m) long with no guard rows. Rows were planted on a 6-ft row center (1.8 m) with 18 inches (0.46 m) between plants, in a 4-tier field design with 6-ft (1.8 m) alleys between tiers. All foliar treatments were applied on 9, 16, and 17 Sep with a 3-nozzle boom equipped with D3 spray tips and powered by a CO₂-backpack sprayer at 40 psi delivering 30 gpa. All plots were maintained according to standard commercial practices.

On 16 Sep, the number of lepidopteran larvae was recorded per five plants using beat sheets. On 23 Sep, 10 small- to medium-size fruit were examined for lepidopteran damage and the number of damaged fruit was recorded. On 4 Oct, 30 marketable-size fruit were harvested and examined for lepidopteran damage. The number of damaged fruit was recorded. Data were analyzed using ANOVA. Means were separated using Tukey’s HSD at the 0.05 level of significance.

Lepidopteran pressure was high with a mean % fruit damage of 62.5 and 44.2 at harvest (Table 1). Visual plant counts of lepidopteran larvae were relatively low but statistically significant with all treatments having significantly fewer larvae than the untreated check except for Endigo ZC (Table 1). Lepidopteran population was comprised of 18% yellow striped armyworm, 35% soybean looper, and 47% corn earworm. On 23 Sep, all treatments had significantly less % lepidopteran fruit damage than the untreated check (Table 1). On 4 Oct, all treatments had significantly less % lepidopteran fruit damage than the untreated check except Endigo ZC (Table 1). No signs of phytotoxicity were observed.

This research was supported by industry grants-in-aid of pesticide and/or research funding from Dow AgroSciences.