Efficacy of Foliar Insecticides for Tobacco Thrips Control in Mississippi Cotton, 2021

In 2021, foliar thrips efficacy trials were conducted to evaluate eight insecticide treatments along with an untreated check on the R.R. Foil Plant Research Facility in Starkville, MS. This trial was planted on May 24 and was conducted as a randomized complete block design with four replications. Plots were four rows wide by 40 feet in length on 38-inch centers. These insecticide treatments were applied with a tractor-mounted sprayer calibrated to deliver 10.0 gpa at 60 psi using TX-6 hollow cone nozzles (2 per row). Insecticide applications were applied on 15 Jun 2021 and treatments were rated 3 and 6 days after treatment (DAT). Efficacy was determined by collecting five plants from the middle rows of each plot and counting the number of thrips through a microscope by using a thrips wash method. The number of thrips immatures and total thrips (adults plus immatures) was reported from each plot. Data were analyzed with ANOVA and means were separated using Fisher’s Protected LSD (P ≤ 0.05).

There were no significant differences among any treatments 3 DAT when assessing the total number of thrips; however, immature thrips populations were significantly reduced by Radiant, Intrepid Edge, and a high rate of Orthene when compared to the untreated check (Table 1). There were no differences among treatments from the untreated check except Warrior II. At 6 DAT, immature thrips were significantly reduced with the use of Radiant compared to the untreated check, Warrior II, Bidrin, or Dimethoate (both rates). However, densities of thrips immatures in the Radiant-treated plots were not significantly different than those in plots treated with Intrepid Edge, Orthene (97 both rates) or Dimethoate (16 oz). Radiant significantly reduced total thrips densities compared to the untreated check and Dimethoate (both rates). Total thrips densities in the Radiant-treated plots were not different than those in plots treated with Intrepid Edge, Orthene 97 (both rates), or Bidrin.¹

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