Efficacy of selected foliar insecticides against thrips in peanut, 2024

The efficacy of Exirel, Orthene, and Radiant broadcast against thrips in peanut was evaluated at Suffolk, VA, in 2024. ‘Bailey II’ seeds (treated with Dynasty PD) were planted on 1 May in a conventionally tilled and bedded field. No at-plant insecticides were applied. Plots were 4 rows wide (36-in row centers) by 40-ft long, in a 4-replicate RCB design. Treatments were broadcast on 23 May with a CO₂-pressurized backpack sprayer calibrated to deliver 14.8 gpa through XR110015-VS nozzles (2 nozzles per row). Since Radiant’s label mentions the use of an adjuvant may increase the level of thrips control, ‘Dyne-Amic’ was tank mixed with that product. Thrips injury and populations were assessed at 7DAT and 13DAT. Thrips injury was estimated visually on a 0–10 scale, where 0 = no injury and 10 = dead plants. To determine thrips populations, 10 unopened (i.e., leaflets still folded) tetrafoliates per plot were placed in soapy water; thrips were separated from the solution using vacuum filtration onto gridded filter paper, then immatures and adults were counted under magnification. Peanuts were dug on 23 September and harvested on 7 October. Yields were determined by combining peanuts from 2 rows of each plot and adjusting to 10% moisture. Data were analyzed using analysis of variance (ANOVA) with means separation using least significant difference (LSD) statistical procedures.

Adult thrips species composition averaged across treatments and sample dates was 75% TT, 20% WFT, and 5% other or not identified. At 7DAT, Exirel and Radiant treatments had significantly less thrips injury than Orthene and the untreated check (Table 1). At 13DAT, Exirel had the least thrips injury. There were no differences in thrips populations at 7DAT. At 13DAT, there were fewer immature thrips in Exirel and Radiant treatments, relative to the untreated check. Yields were not different, with all insecticide treatments numerically higher than the untreated check.

Acknowledgments

This research was supported in part by industry gifts of pesticides.