You Are Here: Management Updates 2005 Archive July 5, 2005

Date: July 5, 2005
Category: Insects
Subject: White Grubs

I was on a golf course in western Massachusetts yesterday (July 4th) and noticed Japanese beetle adults were beginning to swarm on the fairways. This is absolutely "on time" - normally we expect to become aware of Japanese beetle adults right around the holiday, and this year is no exception. Meanwhile European chafers and oriental beetles have been flying for a week or two now in most southern New England locations. (These two species are night fliers, so some people may not see them, but European chafers in particular are attracted to certain trees in a given area and can congregate in huge numbers at dusk, with literally thousands of beetles in a tree.)

For those turf managers in southern New England planning to use some of the slower-acting grub materials (e.g., Merit™ or Mach 2™ or the new product, Arena™), those applications should be made during the first three weeks of July if at all possible. Remember that it is very important to water in these applications with at least 0.1 inch of water, 0.25 inch is even better.

Many areas experienced heavy grub damage last fall or this past spring. While it is difficult to predict what will happen this summer, certainly the grub populations were quite heavy in some locations this spring and the potential exists for significant egg-laying activity from one or more of our grub species.

Weather patterns from mid July to the end of August will have a major impact on the development of grubs. If the summer turns out to be hot and very dry, grub activity may be a little lower than expected because some of the eggs that are laid will desiccate and not develop, at least in unirrigated turf. Or beetles may delay their egg-laying until soil moisture improves, which means that grubs will be slower to develop in late summer. That just means the damage shows up later in the fall, when it is too late to respond! It might be tempting to some to withhold irrigation in some areas, hoping to have a negative impact on the grub eggs. However, it is probably more important to keep the turf properly watered to provide the best agronomic conditions for the grass to withstand summer stresses. Grubs are pretty darned resourceful, and they will find a way to survive!

Submitted by: Dr. Pat Vittum

DISCLAIMER - As always, it is the responsibility of the applicator to verify the registration status of any pesticide BEFORE applying it. Different states have different regulations as well. The author and the University of Massachusetts are not liable for any consequences of any pesticide "recommendations". Mention of any trade name is not to be considered endorsement of a product.

Links followed by the symbol are external links that open in a new window.