Alfalfa Insect Control with Synthetic Pyrethroids, Minnesota, 1982

Experiments were conducted on 2nd and 3rd cuttings of 3rd-year alfalfa at the Rosemount Agricultural Experiment Station, Dakota Co., MN. Plots were 22 x 50 ft (0.025 acre) and arranged in a randomized complete block design with 4 replications. Spray treatments were applied with a tractor-drawn boom sprayer in 27 gal/acre at 100 psi pressure to 2nd cutting on Jun 25 and to 3rd cutting on Aug 5. On 2nd cutting, insects were sampled prespray, Jun 23, and postspray, Jun 28, by taking 25 pendulum sweeps/plot. On 3rd cutting, insects were sampled postspray by vacuum machine taking 15 ‘putdowns’, equivalent to 5.2 ft2 Aug 6, 12, 20, and 20., and by taking 25 pendulum sweeps/plot Aug 6. Ammo at 0.08 lb/acre and Pay-Off at 0.04 lb ai/acre and gave control of pea aphid apterae and potato leafhopper comparable to that provided by 0.5 lb ai/acre of Furadan. There was no evidence that use of the pyrethroids favored beneficial taxa, although only data for parasitic Hymenoptera are shown here. No phytotoxicity was noted.