Have you ever awoken on a crisp fall morning, pulled back the curtains to gaze upon your lawn, and thought for a second that somebody must have vandalized your turf with a shovel? I suspect you probably received a visit from a neighborhood skunk or raccoon.
White grubs are a common pest in cool-season lawns in Virginia because they feed on our lawn's root system during periods when turfgrass growth can be greatly slowed by extremes in temperature and/or moisture. Therefore, most recommendations suggest mid-July to mid-August as a preferred time to apply a grubicide for white grub control in Virginia's cool-season lawns. (Be aware that newly emerging chemistries are touting and doing a pretty good job of delivering "season-long" grub control, so pay attention to updates in labeled chemistry as new products arrive to market). The summer application timing for our standard insecticides is all about controlling grubs when they are at their youngest, most vulnerable stage of development.
This strategy is very appropriate year-in, year-out, but it should be considered that the next generation of grubs is actively feeding on turfgrass roots during the fall until they move deeper into the soil to survive the extreme temperatures of winter. We don't often think of grub damage during the fall because with the arrival of moderating temperatures and fall rains, cool-season turfgrasses usually rebound from the stresses of summer, and any root damage from grub activity is offset by the rapid growth of the grass. However, we can get some really prominent reminders that the grubs are there from some of our four-legged friends (skunks and raccoons) paying our lawn an overnight visit. Skunks and raccoons are foraging for 3rd instar grubs, a tasty, high protein meal for these animals. Their digging action can destroy several square feet of sod in just a matter of hours. So while summer applications are still the norm for applying a grubicide product, if you have a history of skunk or raccoon damage, this is a valid reason to consider a late summer or early fall application of a grubicide to remove the basis for all of the digging in your lawn. I speak from personal experience with this problem as my lawn in Blacksburg was decimated for consecutive years by foraging skunks before I began making a preventive grubicide application in mid-August. Since taking this approach, there has been greatly reduced skunk activity in my lawn.
Dr. Rod Youngman, Extension Entomologist at Virginia Tech, has a thorough discussion of products and strategies in insect control in the lawn and landscape that can be found in the Virginia Cooperative Extension Pest Management Guide for Home Grounds and Animals (pubs.ext.vt.edu). Our Turf and Garden Tips webpage (www.anr.ext.vt.edu/lawnandgarden/turfandgardentips/) provides podcasts, transcripts, and an assortment of other links and attachments of timely topics in homelawn care. And remember that your local extension office is a great resource for information specific to your area.
Dr. Michael Goatley, Jr.
Professor and Extension Turfgrass Specialist
Department of Crop and Soil Environmental Sciences
Virginia Tech
