Are grubs having a picnic with your lawn? 07-30-07

With only a few weeks of ideal growing conditions left for our lawns to recover from summer disease or insect damage, it is important that we do not ignore their presence and control them now. White grubs are the larvae of several species of beetles such as mask chafers, May, June and others that feed below ground, pruning the roots and weakening our lawns.

A full-sized larvae is about one inch long, has a brownish-yellow head, grayish-black posterior, three pairs of legs, and usually found curled in a C-shape These insects may go unnoticed until severe turf damage is done. Make an effort to scout for them by cutting several one to two foot-square samples about two inches deep into the turf and then lifting or rolling the sod back to search for the grubs.

Another sign of grubs is the digging of skunks, raccoons, armadillos, etc. in the lawn. Because grubs are much easier to control when small the best time for control is mid to late summer. It is often difficult to determine the threshold of grubs before treatment is necessary due the turf health from other turf pests, but generally treating is suggested if three to five grubs are found in a one-foot square sample. The danger is that if the grubs weaken the root system just before winter, then it is not until the following spring that any recovery can take place.

When applying insecticides for grub control it is important to water the insecticide into the soil according to label directions. The Extension Web site has several good publications that will help you properly identify lawn pests and give recommendations for their management.

Published July 30, 2007

Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. wwells@ext.msstate.edu