CHEMICAL1 CONTROL OF THREE WHITE GRUB SPECIES (COLEOPTERA: SCARABAEIDAE) ATTACKING FRASER FIR CHRISTMAS TREES IN THE SOUTHERN APPALACHIANS

Field experiments were conducted in 1982, 1983, and 1984 to evaluate the efficacy of several insecticides for controlling white grubs infesting Fraser fir, Abies fraseri (Pursh) Poir., Christmas trees and pastureland scheduled for fir plantings, and to evaluate insecticide phytotoxicity. The white grub complex consisted primarily of three species: Pyllophaga anxia (LeConte) Glasgow, P. fusca (Froelich) Glasgow, and Polyphylla comes Casey. Mean pretreatment white grub population densities ranged from 20.8 to 77.8 grubs per m2. Isazophos, diazinon, carbofuran, carbaryl, trichlorfon, chlorpyrifos, and isofenphos demonstrated a wide range of effectiveness in reducing populations while showing no phytotoxicity to grass sod or fir. Isazophos and diazinon applications provided the highest levels of control.