Potato Leafhopper Control in Alfalfa, 1994

Abstract

Abstract Five insecticides were evaluated for PLH control in a first yr stand of ‘Arrow’ alfalfa located in Montgomery Co., VA in 1994. Plots of 24 × 40 ft were arranged in a RCBD with four replications. A pre-treatment estimate of PLH density was made on 1 Jul. Counts of PLH were made from 4 sets of 10 pendulum sweeps of a 15 inch diam sweep net taken arbitrarily across the field. On 1 Jul, after completing the pre-treatment estimate, foliar insecticide treatments were applied using a CO2 backpack sprayer, delivering 20 gal per acre at 40 psi. Post-treatment estimates of combined PLH nymphs and adults per 10 sweeps were made in all plots on 5, 8, 12, 16, and 22 Jul. Alfalfa stem heights also were determined in all plots on 16 and 22 Jul. Treatment yields were determined at 12% bloom on 28 Jul from 60 ft2 swaths taken from each plot using a sickle-bar mower. Freshly mowed alfalfa was raked into a pile and weighed using a milk scale to determine the wet wt. A 2.2-lb subsample of alfalfa was removed from each plot and dried at 130 to 140°F for 48 h to determine percent dry matter. A two-way ANOVA with Fisher’s protected LSD was used to analyze differences among treatments in PLH sweep net counts (after [x + 0.5]1/2 transformation), stem ht, and dry matter yield for each sample date.