May Beetle Grub Control, North Carolina, 1983

Abstract

Abstract Six soil-applied insecticides were evaluated for efficacy in controlling May beetle grubs in pastureland scheduled for Fraser fir (Abies fraseri) Christmas tree plantings. The test pasture was densely covered with a mixture of annual and perennial grasses accompanied by various broadleaf weeds. The pasture is harvested for hay once a year in early Sept and had been cut just prior to insecticide applications. The mineral-organic Porter loamy soil (2-3% organic matter) located in Watauga Co. had a pH of 5.4, an average temperature of 15.2 degrees C at a depth of 4 inch, and a moisture content of 21% by weight. Test plots measured 10 by 10 ft and contained an average of 5.8 late-stage grubs per sq ft. Each treatment was replicated 5 times; the plots were organized in a completely random design. Pre-treatment grub counts were acquired on 16 Sep, with insecticides applied the same day. One sq ft of sod per plot was turned back to expose feeding grubs. The sod was replaced without injuring the grubs. Liquid insecticides were mixed with 2 gal of water per plot and applied with a hand-pressurized portable sprayer. Granular formulations were applied with a 20” wide hand-pushed spreader. On 16 Oct, posttreatment grub counts were acquired by turning back a previously undisturbed sq ft of sod. Both surviving and dead grubs were counted and percent grub mortality calculated. Grubs at the observed high population density were causing extensive root damage and chlorotic conditions to the sod.