Southern Corn Rootworm Control on Peanut, 1997

Abstract

Abstract Two locations were chosen to evaluate insecticide efficacy and timing for SCR control. Variety NC-7 peanuts were planted at location no. 1 on 18 May and at location no. 2 on 7 May in Bertie County. Peanuts were planted at approximately 100 lb of seed per acre. Thimet 20 G was placed in-furrow at-plant at 5.0 lb product/acre at location no. 1. Temik 15 G was placed in-furrow at-plant at 7.0 lb product/acre at location no. 2. Peanuts were grown under standard agronomic practices as recommended by the N.C. Cooperative Extension Service. Soil at both locations consisted of a sandy loam with location no. 1 comprised of 0.79% humic matter, and a pH of 5.8, and location no. 2 comprised of 2.01% humic matter, and a pH of 5.7. At-plant soil temperature was 70°F at location no. 1 and 72°F at location no. 2 at planting. Plots were 4 rows (36-inch centers) by 20 ft with four replicates per treatment and all treatments were arranged in a RCBD at both locations. Lorsban 15 G at flowering treatments were applied on 16 Jun and pegging treatments on 9 Jul at both locations. Mocap 10 G was applied at late pegging 22 Jul at both locations. Fipronil 1.65 G was applied at-plant on 14 May at location no. 1 and on 22 May at location no. 2. All treatments were applied by using a bicycle-wheel granular applicator utilizing a Noble metering unit. Some of the early-season treatments did not provide significant control because dry soil conditions were unfavorable and resulted in a reduction in the egg survival. Late-season rains provided perfect field conditions for egg survival and thus created a later than normal outbreak of rootworms. Therefore, treatments applied late in the season seemed to have provided the highest level of control. Peanuts were sampled for rootworm damage at both locations on 20 Sep by collecting 100 pods at random from 5 plants in the two left-hand rows. Pods were placed into plastic bags and returned to the laboratory for examination. Damage was rated by recording the number of pods that had one or more root-worm feeding scars or punctures. Yield was determined by digging, drying, and weighing peanuts from all 4 rows of each plot on 7 Nov at location no. 2. All data were transformed (square root ofx = 0.05) prior to ANOVA and DNMRT.