HORTICULTURAL ENTOMOLOGY Management of Early-Instar Japanese Beetle (Coleoptera: Scarabaeidae) in Field-Grown Nursery Crops

Numerous Þeld studies were conducted in commercial nurseries in Tennessee from 1996 through 1999 to evaluate chemical and biological treatments, application timing and rates, and method of application for control of early instars of Japanese beetle, Popillia japonica Newman. Insecticide treatments included bifenthrin, bendiocarb, chlorpyrifos, carbaryl, Þpronil, halofenozide, imidacloprid, permethrin, teßuthrin, thiamethoxam, and trichlorfon. Biological treatments included entomopathogenic nematodes (Heterorhabditis bacteriophora HP88 or H. marelatus), Bacillus thuringiensisBerliner subspecies japonensisBuibui strain, andBeauveria bassiana (Balsamo) Vuillemin. All treatments were applied on the soil surface or injected into the soil around the base of each tree. Tree type and size varied among and within tests, however, the sampling unit (61-cm-diameter root ball) remained the same throughout all tests. The biological treatments provided poor-to-moderate control (0Ð75%) of Japanese beetle larvae. Imidacloprid was the most frequently evaluated insecticide and achieved 91Ð100, 87Ð100, 83Ð100, and 41Ð100% control with applications in May, June, July, and August, respectively. Halofenozide treatments were not signiÞcantly different from imidacloprid treatmentswith one exception.Halofenozide provided 60Ð87, 85Ð100, and 82Ð92 control with applications made in June, July, and August, respectively. Fipronil and thiamethoxam were evaluated to a lesser extent but both performed similarly to imidacloprid. Most other insecticide treatmentswere less successful in reducingnumbers of Japanese beetle larvae and with few exceptions achieved 50% control.