The Green Section office in Wisconsin always receives a few additional inquiries about Japanese beetle grub survival every time a mild winter occurs. Everyone wants to hear that a lack of snow cover and above average temperatures will disrupt the life cycle of this pest and ultimately reduce or eliminate populations overwintering grubs.
A little help from Mother Nature regarding grub control would be a welcome bonus considering the high cost of pesticide treatments for fairways and roughs, where most turf loss occurs, versus the more modest expense of treating only a few acres of putting surface where relatively little grub injury is typically observed.
To make matters worse, courses affected by the most severe infestations of grubs are often in sites where Japanese beetle populations have just become well established as they slowly migrate westward across the Region. There tends to be minimal natural control of grubs or adult beetles from disease, parasites, etc. for as long as five to eight years when they invade new turf. During this time, beetle populations can go hog wild and make life miserable for superintendents who are not yet familiar with the direct and indirect effects of grubs making a permanent home in high quality turf.
Japanese beetle control is old hat for superintendents across the eastern part of the country - scout for grubs, identify the pest species, budget for control measures and treat affected turf at the appropriate time only when necessary, as dictated by factors such as pest population levels, weather conditions and turf health. In contrast, the migration and establishment of beetles into new territory is an unsettling event for a golf course. There is the obvious injury to susceptible trees and ornamental plantings caused by adult beetles and the not so obvious, but equally serious, injury to turf caused by grubs. The additional turf disruption caused by skunks and raccoons foraging for grubs at night adds insult to injury. Furthermore, this trifecta of turf trouble was unexpected, so the chances of you having funds already in the budget earmarked for grub control are about as good as the chances you have of getting that angry skunk out of the live trap without stinky repercussions.
Well, the good news is that winter has been unusually mild. The bad news is that the grubs are probably just fine as they have their own form of antifreeze to compensate for the lack of snow cover. Even better news is that there are plenty of options available for effective grub control and several of the reduced risk products developed recently are much more eco-friendly than the materials available for insect control 20 or 30 years ago.
Spend some of the time that you are not spending behind a snow plow to learn more about the new classes of insecticides and how they might fit into a responsible, sustainable turf maintenance program if new bugs are bugging you. Feel free to call the office anytime with questions regarding the best time to treat for specific insect problems and ways to stretch the budget by using new products to control multiple turf pest species.
Source: Bob Vavrek, rvavrek@usga.org or 262-797-8743