Alfalfa Insect Control in Oklahoma, 1980-81

Insecticides were evaluated on 5 x 10 m plots arranged in a randomized complete block design with 4 replications. Applications were made with ground equipment using a spray volume of 20 gpa. Treatments were applied in the first crop of alfalfa on Apr 18, 1980 (Test 1) and on Mar 10, 1981 (Test 2). Insect populations were sampled at 3 intervals after application. Ten-sweep samples were taken in each plot for each sampling date in 1980 and numbers of alfalfa weevil larvae and pea aphids were recorded. Due to much smaller size of alfalfa at the time of treatment in 1981, 25 stems/plot were clipped at the soil surface. Stems were brushed, then processed in ‘Berlese’ funnels to remove all weevil larvae and spotted alfalfa aphids for counting.