Control of Alfalfa Weevil Larvae in Tennessee, 1986

Twenty-five insecticide treatments were evaluated in a 4-yr-old stand of alfalfa at the Middle Tennessee Experiment Station, Spring Hill. Plots were 20 × 20 ft replicated 4 times in a randomized complete block design. Blocks were separated by 15 ft alleys. Furadan 4 F (1.0 lb (Al)/acre) was applied on 6 Mar when the alfalfa was in the stubble stage. All other treatments were applied on 4 Apr when 90% of the tips were infested. Insecticides were applied using a tractor mounted CO2-powered 10 ft boom sprayer at the rate of 30 gal/acre. Insect samples were collected on 7, 11 and 18 Apr using a 15 inch insect net and consisted of 5 pendulum sweeps from each plot. Pre-treatment means were 16 alfalfa weevil larvae (AWL) per 5 sweeps. A 5 × 20 ft strip was harvested from the middle of each plot on 6 May. Subsamples were dried for yield determinations.