Six insecticides and/or rates were applied for efficacy data collection for Empoasca sp. leafhoppers and threecornered alfalfa hoppers. Data were also collected on a number of other insects present. Samples were collected one, four, seven and ten days post treatment. Yield and quality data were obtained after baling. Data indicated that several insecticides effectively controlled threecornered alfalfa hopper, as well as provided control of Empoasca leafhoppers. The Baythroid 2 treatment increased yields by 0.3 tons/acre (35%) compared with the check, but yields across the various treatments did not correlate with insect control. Quality from the various treatments was similar. Application of Baythroid 2 at 2 oz/acre increased net return by $7.63/acre due to increased yields. No postiive economic returns were realized from any of the other treatments in this experiment.

This report summarizes data from several studies conducted along the Colorado River in recent years for control of Empoasca sp. leafhoppers, threecornered alfalfa hoppers, and western big-eyed bugs. Data were rearranged and presented in an easy to understand format for insect pests control utilizing a time sequence corresponding to sampling dates after application, a method not always readily available.

"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. "

An experiment was initiated utilizing a swather based sprayer to determine if miticides applied at cutting would be an effective control method of spider mites in low desert alfalfa hay. Two treatments (Trilogy, Trilogy + Kinetic) were applied the morning of May 23, 2003, to alfalfa with very high numbers of spider mites. Treatments had five replications, with plots sampled on June 2, 9 and 18. Data indicated a severe reduction in spider mite numbers as of June 2 in all treatments (including untreated) thought due to high temperatures experienced shortly after cutting that exceeded lethal thresholds for spider mite survival. Differences in treatments for spider mites or western flower thrips were not noted until June 18, when significantly fewer spider mites were noted in Trilogy treated plots than untreated check plots. Trilogy + Kinetic treatments resulted in numerically fewer spider mites than the untreated check on this sample date, but numerically more than Trilogy treatment.