You Are Here: Management Updates 2003 Archive April 22, 2003

Date: April 22, 2003
Category: Insects
Subject: White Grubs, Annual Bluegrass (Hyperodes) Weevil

European chafer grubs have been up and feeding for a few weeks now, and their "cousins" (e.g., Japanese beetles and oriental beetles) seem to be arriving in the root zone now. The recent warm weather began to raise soil temperatures and now most grubs are back in their preferred sites, feeding on roots and root hairs. Several people are encountering the related secondary damage, when skunks or raccoons (or crows or starlings) tear up the turf, getting to those tasty morsels.

If a turf manager is facing an irate client and needs quick relief, trichlorfon (Dylox™) is the quickest acting insecticide available. Note, however, that it is on the "School IPM" restriction list, so folks managing athletic fields on school grounds will not have that option. Meanwhile also note that spring applications of Merit™ will not affect the grubs that are currently present in the root zone. Unless there are extenuating circumstances, imidacloprid (Merit™) should not be applied any earlier than early June - and that would be to protect against grubs that emerge in July or August of this year. In general mid June to mid July would be even better for a Merit™ application.

As always, be sure to water in any application that is being targeted for white grubs. I suspect many of the "failures" reported from last year can be traced to a failure to follow an application with adequate water. Admittedly, it was very difficult to follow with water in August or September of 2002 because of the drought and related water restrictions, but it confirms the importance of watering-in. Also if Merit™ applications were made in August targeting European chafer grubs, those applications were probably a little bit too late.

For readers in western Massachusetts, please be advised that we found European chafer grubs on the UMass Amherst campus last spring (2002), as well as in Holyoke. This year we have already confirmed their presence in Sunderland, just north of Amherst. It is safe to assume they will appear in other towns along the Connecticut River as well - so be prepared to make some adjustments in your grub strategies. Remember that the life cycle of the European chafer is about two weeks earlier than the Japanese beetle, so insecticide applications need to be made earlier.

Annual bluegrass weevil
As Forsythia begin to bloom in central New England, keep in mind that the annual bluegrass weevil will not be too far behind. This is strictly a golf course problem, so landscapers can relax for the time being. Chlorpyrifos (Dursban™) continues to be available for use on golf courses, but the application rate has been limited to 1 pound active ingredient (AI) per acre. There is, however, no limit on the number of applications you make. We have found that an application when Forsythia is "half green-half gold", followed by a second application two weeks later, is very effective. Alternatively, you can use any of the synthetic pyrethroids that are labeled for use on golf courses - same timing. Water lightly, just one or two passes of the irrigation head.

So there you have it - we are off and running!

- Submitted by: Dr. Pat Vittum