Abstract
Abstract This test was conducted on a field of ‘Cimarron’ alfalfa at the Southcentral Research Station in Chickasha, Okla. Efficacy of several foliar insecticides was determined for AW larvae, PA, and BAA. Pretreatment counts made 21 Mar indicated an infestation level for AW in excess of the economic threshold (1.5 larvae/stem). PA numbered less than 1/stem, and there were approximately 20 BAA/stem. Insecticides were applied 21 Mar with a tractor-drawn boom sprayer equipped with flooding nozzles and calibrated to deliver 20 gal/acre at 20 psi. Plots were 4.0 by 7.0 m, arranged in a randomized complete block design with 4 replicates. AW population densities were estimated from 25 stem samples taken from each plot on each posttreatment sampling date. Larvae were extracted from foliage with Berlese funnels prior to counting. Efficacy data for control of each aphid species were determined by clipping 10 stems/plot and washing the aphids into jars of alcohol for counting and identification. Yield was determined by harvesting a 1.0- by 5.0-m area from each plot using a Carter harvester.
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