Southern Corn Rootworm Control in Peanuts, North Carolina, 1989

Abstract

Abstract A field on the Morrell Jones farm in Halifax Co. was chosen to test several insecticide treatments for control of the southern corn rootworm. Peanuts were planted on 30 May (90 lb seed/acre), and standard agronomic practices were used in the production as recommended by the N.C. Agricultural Extension Service. Thimet was applied in the seed furrow at 1 lb (AI)/acre by the cooperator. Soil humic matter was 0.9% and soil temperature was 71°F at 3 inches. Plots were 4 rows (36 inch centers) × 20 ft with 4 replicates/treatment, and treatments were arranged in a randomized complete block. Most treatments were applied at pegging time; however, some insecticides had other application timings as indicated in the table below. The pre-plant incorporated Lorsban treatment was applied just prior to planting by spraying the insecticide as a broadcast treatment over the plot area and immediately incorporating the material with a hand rake. Sprays were applied using a CO2- pressurized backpack sprayer delivering 30 gal/acre at 40 psi using boom-mounted 8002 flat-fan nozzles. The Lorsban at plant application of granular insecticide was applied immediately after planting with a bicycle-wheel granular applicator utilizing a Noble metering unit and placing the insecticide in a 16-inch band. This insecticide was also lightly incorporated with a rake. At-flower treatments were applied on 27 Jun using the same bicycle-wheel granular applicator to apply a 16-inch wide band. At-pegging treatments were applied on 11 Jul, using the same granular applicator. A delayed treatment of Lorsban and one of Mocap were applied 1 Aug. In addition, 2 treatments consisted of foliar sprays applied on 25 Jul and again on 1 Aug. Growing conditions were unusually wet all season long which greatly enhanced the potential for rootworms and increased the potential for leaching of the soil-applied insecticides. Peanuts were sampled for rootworm damage on 11 Sep by collecting 100 pods at random-from plants in the 2 left-hand rows of the plots. Pods were placed in plastic' bags and returned to the laboratory and examined for rootworm damage. Peanuts were dug 7 Oct and harvested 16 Oct. Yield was determined by harvesting and weighing all pods in the two right-hand rows of the plots. Data were subjected to analysis of variance and means separated by Duncan's New Multiple Range Test. All data were transformed X + 0.5 prior to analysis, but actual means were reported.