Evaluation of experimental insecticides and biopesticides for control of southern armyworm (SAW) on staked tomato in Southwest Florida, 2022

Southern armyworm is a serious pest of tomatoes grown in Florida. It can cause significant yield losses in tomatoes by feeding on plant foliage and fruit. For this trial at the University of Florida–IFAS Southwest Florida Research and Education Center in Immokalee, greenhouse-raised seedlings were transplanted on 20 Sep at 18-inch spacing on 2 raised beds set on 6-ft centers, each bed was covered with white-faced polyethylene film. Plots of 15 plants, each separated by 3 feet were assigned to 4 replicates and 7 treatments and an untreated check in an RCB design. Foliar insecticide treatments for suppressing SAW were applied using a high-clearance sprayer with 2 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 60–80 gpa (Table 1).

Ten 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. Seven plants from each plot were harvested on 22 Dec. 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 (P = 0.05).

The population of SAW was extremely light this season. A statistically significant reduction compared with the untreated control in the number of SAW larvae was observed in all treatments on 16 Dec and in damage on 2, 9, and 16 Dec (Table 2). There was no statistically significant difference in the number or weight of the fruit among treatments (Table 3), but all treatments were able to significantly reduce the number of fruit culled from SAW damage when compared to the untreated check.

No phytotoxicity was observed.¹

Footnotes