Evaluation of Regent Insecticide for Early Season Insect Control in Corn, 1996

Abstract

Abstract This experiment was designed to test Regent applied at planting and at the whorl stage for the control of WCR and com borer larvae. Plots were planted at 30,600 seed/acre on 9 May in a furrow-irrigated field at the Southwest Research-Extension Center, in Finney County, KS. The field was pre-watered on 9 Apr, but the seed-bed dried out and the field was watered again on 24 May to complete emergence. The soil type was a Richfield silt loam with a pH of 7.5 and an organic matter content of 1.5%. Plots were 2 rows (5 ft) by 50 ft long, arranged in a RCB design, and replicated four times. Plots wre separated by 10 ft alleyways at the end of each plot and with 4 rows of border com between plots. Planting time granular treatments were applied as a 7-inch band over the open seed-furrow (T-band) or into the open seed-furrow (in-furrow) with planter-mounted John Deere granular applicators. The liquid applications at planting were made with a CO2 backpack sprayer mounted on the planter with nozzles directed into each furrow delivering 1.5 gpa. Rootworm damage was evaluated on 4 plants from each plot on 9 Jul using the 6 point Iowa scale. Plant stunting was also visually rated as percent reduction in biomass relative to the best WCR treatment (Counter). The banded treatment on 8-inch com was made 13 Jun with a hand sprayer. Whorl stage applications were made on 11 Jul using a high clearance sprayer with three nozzles directed at each row and calibrated to deliver 20 gpa at 2 mph and 40 psi. A total of 6.5 inches of rain was recorded between planting and taking the root ratings and another 1.3 inches of rain was recorded between 9 Jul and 19 Jul when the corn borer ratings were taken. To assure first generation com borer pressure, 5 ECB egg masses were pinned to every 3rd plant in a 15-plant marked section in each plot on 25 Jun. These plants were evaluated for com borer injury on 19 Jul using the Guthry scale and by dissecting plants to determine the number of com borers and the amount of tunneling. Second generation damage was evaluated on 30 Sep by dissecting 15 plants in each plot. Yields were taken by mechanically harvesting each plot and taking row measurements to correct for gaps created by the destructive sampling.