Abstract
Abstract Nine chemical insecticide treatments were evaluated for efficacy in controlling AW larvae and aphids on a second year stand of ‘Cimarron’ alfalfa located at the Agronomy Research Station, Stillwater, OK. Pretreatment samples indicated a population of 3.3 AW larvae/stem, while aphid numbers averaged 45 per 25 stems. Sprays were applied on 9 Apr using a tractormounted boom sprayer equipped with flooding nozzles (Spraying Systems Co., TK SS-5) calibrated to deliver 20 gpa at 24 psi while traveling at 3.0 mph. Plot size was 5 × 8 m, arranged in a randomized complete block design with 4 replications. Efficacy of treatments was determined from samples of 25 stems pulled from each plot at 2, 7, 14, and 21 DAT. Standard Berlese funnels were used to extract AW larvae and aphids from the stem samples for counting. Subsamples of aphids were examined on each date for species determination. Dry matter yield estimates were made by harvesting two 0.5 m quadrates from each plot on 14 May and drying forage before weighing and calculating yield on a per acre basis.
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