Potato Leafhopper Control In Alfalfa, 1995
Abstract Three insecticide treatments were evaluated against PLH in a firstyear stand of ‘Haymaker ’ alfalfa located in Montgomery Co., VA. Plots of 24 X 40 ft were arranged in a RCBD with an untreated check in each of 4 replications. Mean alfalfa stem height and PLH density were estimated in each plot prior to spray treatment (21 Jul). Potato leafhopper density was estimated using combined counts of PLH nymphs and adults from 10 pendulum sweeps of a 15-inch diam sweep net taken arbitrarily across the plot. All insecticide treatments were applied as foliar sprays on 21 Jul using a CO2 backpack sprayer, delivering 20 gpa at 40 psi. Post-treatment alfalfa stem height and PLH densities were sampled every 3 to 4 d in each plot until harvest (14 Aug). Yields were determined from 60 ft2 swaths taken from each plot using a sickle-bar mower. Freshly mowed alfalfa was raked into a pile and weighed by hand using a milk scale to determine the wet wt at harvest. A 2.2-lb subsample of alfalfa was removed from each plot and dried at 131 to 140°F for 48 h to determine % dry matter. Forage samples were submitted to Virginia Tech Forage Testing Laboratory, Blacksburg, VA, for quality analysis, including % crude protein and % acid detergent fiber. A twoway ANOVA with Fisher ’s protected LSD was used to analyze differences among treatments in PLH sweep net counts (after [x + 0.5 ½ transformation), stem ht, dry matter yield, % crude protein, and % acid detergent fiber.