Management of early-instar Japanese beetle (Coleoptera : Scarabaeidae) in field-grown nursery crops

Numerous fleld studies were conducted in commercial nurseries in Tennessee from 1996 through 1999 to evaluate chemical and biological treatments, appl ication timing and rates, and method of application for control of early in stars of Japanese beetle, Popillia japonica Newman. Insecticide treatments included bifenthrin, bendiocarb, chlorpyrifos, carbaryl, fipronil, halofeno zide, imidacloprid, permethrin, tefluthrin, thiamethoxam, and trichlorfon. Biological treatments included entomopathogenic nematodes (Heterorhabditis bacteriophora HP88 or H. marelatus), Bacillus thuringiensis Berliner subspe cies japonensis Buibui strain, and Beauveria bassiana (Balsamo) Vuillemin, All treatments were applied on the soil surface or injected into the soil a round the base of each tree. Tree type and size varied among and within tes ts, however, the sampling unit (61-cm-diameter root ball) remained the same throughout all tests. The biological treatments provided poor-to-moderate control (0-75%) of Japanese beetle larvae. Imidacloprid was the most freque ntly evaluated insecticide and achieved 91-100, 87-100, 83-100, and 41-100% control with applications in May, June, July, and August, respectively. Ha lofenozide treatments were not sig nificantly different from imiducloprid t reatments with one exception. Halofenozide provided 60-87, 85-100, and 82-9 2 control with applications made in June, July, and August, respectively. F ipronil and thiamethoxam were evaluated to a lesser extent but both perform ed similarly to imidacloprid. Most other insecticide treatments were less s uccessful in reducing numbers of Japanese beetle larvae and with few except ions achieved < 50% control.