Potato Leafhopper Control, 1995

Two tests were conducted to evaluate the efficacy of insecticides against PLH. The experiments were conducted at the Russell E. Larson Agricultural Research Center at Rock Springs, Centre County, PA, on the second and third alfalfa crops. Plots of 40 X 40 ft were arranged in a RCBD with an untreated check in each of 4 replications. Potato leafhopper densities were estimated on 19 Jun (Experiment I) from 20 pendulum sweeps of a 15 inch diam insect beating net taken randomly across each plot. All insecticide treatments were applied as foliar sprays on 20 Jun. Alfalfa height at application was 4–6 inches. Leafhopper densities were sampled on 23, 29 Jun and 5, 11, and 18 Jul (3, 9, 15, 21, and 28 DAT). Densities reported represent combined adult and nymphs collected per 20 sweeps. Insecticides were applied in 25 gal of water per acre at 25 psi with a tractor-mounted sprayer equipped with a 20 ft boom containing 80° fiat fan nozzles and 50 mesh screens. Alfalfa yield was determined on 19 Jul from a 60 ft2 swath taken from each plot with a Carter Forage Harvester (Carter Mfg. Co. Inc., Brookston, IN). Insecticide treatments in Experiment II were similarly applied on 31 Jul. Potato leafhopper density was determined from sweep samples on that same date before the foliar sprays were applied. Thereafter, leafhopper densities were determined from sweep samples on 3, 8, 15, 21, 28 Aug (3, 8, 15, 21, and 28 DAT). Alfalfa yield was determined on 29 Aug as in Experiment I.