Evaluation of Foliar Insecticides for the Control of Foliar Insects in Summer Squash in Virginia, 2016

The objective of this experiment was to assess the efficacy of foliar insecticides for the control of melon aphids in summer squash. The experiment was conducted at the Virginia Tech Eastern Shore Agricultural Research and Extension Center in Painter, VA and consisted of eight treatments arranged in an RCB design with four replicates. ‘Gold Star’ summer squash was planted on 15 Jul 2016. Plots were one-row wide and 20-ft (6.1 m) long. Rows were planted on a 6-ft row center (1.8 m) with 18 inches (0.46 m) between plants, in a six-tier field design with 8-ft (2.4 m) alleys between tiers. All foliar treatments were applied on 16 and 23 Aug. Foliar treatments were applied 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 19, 23, and 30 Aug, the number of squash bug life stages was recorded per five plants. On 23 and 30 Aug, and 6 and 13 Sep, the number of melon aphids was recorded per 10 squash leaves. On 30 Aug and 6 Sep, the number of green peach aphids was recorded per 10 squash leaves. On 19 Aug, the number of live cucumber beetles was recorded per 10 squash blooms. On 19 and 30 Aug, the number of dead cucumber beetles was recorded per five plants. On 23 and 30 Aug, plots were harvested and the number of fruit was recorded per plot. Weight in lbs was recorded per plot on 23 Aug. On 30 Aug, the number of live plants per plot was recorded. On 30 Aug, the number of diseased fruit was recorded per plot. Data were analyzed using ANOVA. Means were separated using Tukey’s HSD at the 0.05 level of significance. Data were square root transformed when necessary.

Squash bug pressure was moderate and was comprised of squash bug and leaf-footed bugs. Results were not significant on 23 and 30 Aug except for adult counts on 30 Aug. On 30 Aug, all treatments had significantly fewer adult squash bugs than the untreated check (Table 1). Aphid pressure was moderate. Melon aphids first colonized plants, followed by the presence of green peach aphids on 30 Aug and 6 Sep. On 23 Aug, Sivanto 200SL at the high rate and Beleaf 50SG had significantly fewer melon aphids than the untreated check (Table 2). On 30 Aug, all treatments had significantly fewer melon aphids than the untreated check except Movento, Harvanta 50SL at the low rate and Warrior II (Table 2). On 30 Aug, all treatments also had significantly fewer total aphids than the untreated check except Movento, both rates of Harvanta 50SL and Warrior II (Table 2). On 6 Sep and 13 Sep, Warrior II had significantly more total aphids than the untreated check (Table 2). No other treatments were significantly different from the untreated check for aphid counts. Cucumber beetle pressure was moderate with 17.8 live beetles per 10 blooms in the untreated check on 19 Aug (Table 3). On 19 Aug, results were not significant in comparison to the untreated check for live beetles in blooms (Table 3). On 19 Aug, only Sivanto 200SL at the high rate had significantly higher numbers of dead cucumber beetles than the untreated check (Table 3). On 30 Aug, Sivanto 200SL and Harvanta 50SL at the high rate had significantly higher numbers of dead cucumber beetles in comparison to the untreated check (Table 3). Differences in yield were not significant (Table 4). No signs of phytotoxicity were observed.

This research was supported by industry grants-in-aid of pesticide and/or research funding from ISK Biosciences and Bayer CropScience.