Comparison of Proclaim Opti to Other Commercial Insecticides for Control of Southern Armyworm on Staked Tomato in Southwest Florida, 2020

Southern armyworm can cause severe defoliation and fruit damage resulting in significant yield losses on tomatoes grown in Florida. For this trial at the University of Florida-IFAS Southwest Florida Research and Education Center in Immokalee, greenhouse-raised seedlings were transplanted 10 Sep. at 18-inch spacing on three raised beds set on 6-ft centers; each bed was covered with white-faced polyethylene film. Plots of 25 plants each separated by 10 buffer plants were assigned to 4 replicates and 6 treatments and an untreated check in an RCB design in four rows (Table 1). The center bed of each three-bed section was left untreated and served as a uniform source of pests and spray buffer. Foliar insecticide treatments directed at SAW were applied using a high clearance sprayer with two vertical booms operating at 180 psi. Each drop boom was fitted with horizontally directed ATR 80 hollow cone nozzles delivering 10 gpa with a total spray volume of 80 gpa. Applications were conducted on 4 and 18 Nov.

Fifteen centrally located plants per plot were visually inspected, and larvae were counted within three categories: small (first and second instars), medium (third and fourth instars), and large (fifth and sixth instars). The amount of defoliation was estimated per plant. Defoliation was rated as follows: 0 = no damage; 1 = <5% damaged, 2 = between 5 and 33% damaged; 3 = between 33 and 67% damaged; and 4 = >67% damaged. Eight plants from each plot were harvested on 24 November and 10 December. Fruit was graded by size, and the total number of fruit in each size category was counted and weighed. Culled fruit due to SAW feeding were counted in each plot. Data were subjected to ANOVA with means separated using LSD (α = 0.05).

All treatments had significantly less SAW larvae on all three sample dates (Table 1) and correspondingly all treatments had significantly less defoliation than the untreated check. Treatment differences amongst the products were only observed on 30 November (Table 1).

All treatments significantly reduced the number of SAW damaged fruit and correspondingly increased the number of marketable fruit and total weight of collected fruit on the first harvest date of 24 November (Table 2). On the second harvest date, there were no statistically significant differences between the number of SAW damage fruit. The number of marketable fruit collected from the Besiege treatment on the second harvest was not different from the untreated check, but this was probably due to the higher yield in the first harvest and a lost plot due to cattle rummaging in the field.

No phytotoxicity was observed.

This experiment was supported partly by industry funding and pesticides.