Potential Acaricides for Management of Blueberry Bud Mite in Michigan Blueberries

Abstract

The goal of this study was to evaluate potential alternatives to endosulfan for control of the blueberry bud mite (Acalitus vaccinii), because the availability of this acaricide may be restricted in the future. Laboratory evaluations of potential acaricides showed that endosulfan and a combination of abamectin plus oil provided 97% and 100% control, respectively. Pyridaben and fenpropathrin were less effective, reducing mite survival by 49% and 57%, respectively. Further laboratory evaluation of the abamectin plus oil treatment showed that each component applied alone provided a high level of control of blueberry bud mite. Field trials in Michigan on a mature highbush blueberry (Vaccinium corymbosum) planting were conducted to compare control of this pest by postharvest applications of endosulfan, delayed-dormant application of oil, or a combination of both treatments. The oil provided a 40% reduction in mite scores, while endosulfan was more effective (48%) and similar to the combination of endosulfan and oil (52%). A separate field trial using a multifan/nozzle sprayer that applied the pesticide in 233.8 L·ha-1 (25 gal/acre) of water suggested that the level of control from one application of endosulfan was not as effective as two applications. Results are discussed in relation to developing future bud mite control programs in blueberry and the need to address gaps in our understanding of the biology of blueberry bud mite. Endosulfan (Thiodan 50 WP), Endosulfan (Thiodan 3 EC), Abamectin (AgriMek 0.15 EC), Fenpropathrin (Danitol 2.4 EC), Pyridaben (Pyramite 60 WP).