Evaluation of various miticidal products for two-spotted spider mite, alfalfa caterpillar, and beet armyworm control in alfalfa

Abstract

"A number of products with miticidal activity were applied both in the spring and summer of 2002 to alfalfa in the Blythe, CA, area to evaluate their efficacy for twospotted spider mite (Tetranychus urticae) control. These two application periods differed in regards to presence of western flower thrips (Frankliniella occidentalis), a predator of spider mites. Western flower thrips populations were high in the spring but essentially absent during the period following the summer application, providing contrasting data for effects of western flower thrips interactions with many miticides for spider mite control. Miticides tested included those currently utilized for mite control in alfalfa hay production as well as a number of new and/or potential products for alfalfa hay. In the spring testing, most treatments had more spider mites than the untreated check at three days post treatment when western flower thrips were present and actively feeding on spider mites. Two fertilizer treatments that contained high amounts of sulfur also had more spider mites than the untreated check at three days post treatment, thought due to repellency of adult western flower thrips. Many of the treatments that had more spider mites than the check following the spring application are known to have thrips activity (Zephyr, Trilogy, Dimethoate, Lorsban, etc.). Fewer motile (adults and immatures, not eggs) spider mites than in the check were noted only from the Capture + Dimethoate 400, Capture, and the combination of the two Gowan numbered products (1528, 1549) at three days after treatment. Products that provided excellent (90%+) control throughout the duration of the summer part of the experiment included two numbered compounds from Gowan (1528 and 1549), Capture + Dimethoate 400, Danitol, Zephyr + Trilogy, and a numbered compound from Valent USA (V-1283). The wide disparity in the two data sets indicate that western flower thrips presence/absence should be considered as part of the decision making process for spider mite control. "