Evaluation of Soil Insecticides for Early Season Control of Thrips on Peanuts, 1993

Abstract

Abstract ‘Okrun’ peanuts were planted at approximately 5-6 seeds/ft on 19 May into a Larton loam fine sand soil at Gary Weger Farms in Bryan County, Oklahoma. Plots measured 4 rows by 25 ft, with rows spaced 36- inches apart and each plot was separated by 5 ft long buffers within rows. All treatments were replicated four times in a RCB design. Broadcast preplant incorporated (BC-PPI) treatments were applied on 18 May with a wheel barrel sprayer calibrated to deliver 14.5 gal/acre at 20 psi through 8003 flat fan nozzles spaced 18 inches apart on the boom and incorporated into the soil approximately 2 ft deep with a rototiller. In-furrow (IF) treatments were applied into the seed furrow at planting using a 71 John Deere flexi-planter equipped with granular boxes. Sixinch band treatments were applied at planting with a Precision Granular Applicator® and lightly incorporated into the soil with a rake. Conventional cultural practices were used throughout the trial and irrigation was provided as needed with an overhead ride roll system. Peanut plants were rated for thrips damage on 18 Jun and 12 Jul by examining 5 plants from the middle 2 rows of each plot and estimating the percentage of leaf area affected by thrips damage. Thrips damage was rated on a scale of 1-5: 1 = none (0%); 2 = low, minimum damage to leaves with few leaves puckered (1-25%); 3 = moderate, majority of leaves puckered (26-50%); 4 = high, puckered leaves and slight stunting (51-76%); and 5 = severe, heavily puckered leaves and severe stunting (75-100%). Thrips populations were assessed on 12 Jul by sampling 5 trifoliate leaflets and 10 blooms per plot from the same 5 plants rated for thrips damage. Samples were immediately placed in 200 ml of 70% ethyl alcohol and later rinsed thoroughly and strained to dislodge and separate any thrips caught in plant tissue. Strained samples were poured through a porcelain Buchner funnel lined with filter paper and examined for thrips. Analyses of variance were used to analyze data and means were separated with Ryan-Einot-Gabriel-Welsch multiple range test (P ≤ 0.10).