Alfalfa Weevil Control, 1993

Abstract

Alfalfa weevil control was evaluated at 2 locations near Rapid City and I location near Gregory. Treatments consisted of various cultural methods and insecticides applied in a final spray volume of 20 gal per acre at 35 psi using a hand-held sprayboom consisting of 4, 8002S nozzles on 19 inch centers. Insecticide applications were made on 9 Jun at both Rapid City locations and 10 Jun at the Gregory location. Plots were 30 ft × 30 ft. Treatments were arranged in a RCBD with 3 replications per treatment. Early harvest was made on the insecticide application date at all locations. Cultivation treatments were made at the time of alfalfa green up and consisted of a single pass with a spring-tooth harrow at the Rapid City location 1 and a single pass with a tandem disc at the Gregory location. Flaming treatment at Gregory consisted of a single pass over plots with a tractor-mounted propane flamer at the time of initial alfalfa growth. Alfalfa weevil density was evaluated prior to insecticide treatments and 7 and 14 DAT by taking 10 sweeps from each plot using a standard 15 inch sweep net. Larval densities are expressed as mean number of alfalfa weevil larvae per 10 sweeps. Yield was determined from a 45 ft2 area in the center of each plot.