You Are Here: Management Updates 2005 Archive July 19, 2005

Date: July 19, 2005
Category: Insects
Subject: White Grubs, Annual Bluegrass (Hyperodes) Weevil

White grubs
I have had several reports from people throughout New England reporting plenty of adults flying - Japanese beetles, oriental beetles, asiatic garden beetles, European chafers. You name it, they are out and about. One intrepid reporter told me his swimming pool (in Granby, Massachusetts, just south of Amherst) was loaded with oriental beetles and asiatic garden beetles the last couple nights. As he skimmed the pool, more beetles piled in.

When soils are very dry in the summer, beetles often delay their egg-laying activity until soils get wetter. This year there will be no delay! Soils are plenty moist, and egg laying is already underway. And grubs seem to be surprisingly resilient in wet soils. Last year we sampled an area just a few days after it had been flooded for three days, and the grubs (European chafers) were just fine, as healthy as could be. So the wet soils many of us currently have probably will not discourage grub activity at all.

Several people have asked me about imidacloprid (Merit™) applications for grubs. Normally we recommend that the applications be made by the end of July if possible, but this year the wet soils are having an impact. Do not apply Merit™ (or any other grub material) when soils are saturated. It is better to wait until soils dry out a bit. And applications that are in place by 10 August or so should work fine in most cases. The exception would be south-facing slopes in areas where European chafers are the primary grub species. In those situations, try to get the material down by the end of July if at all possible. Dave Shetlar, my colleague at Ohio State University, says that his studies have indicated that Merit™ can be used even later in the summer if necessary. The main "rule" this summer is to avoid treating when soils are saturated.

Annual bluegrass weevils
It's official. As far as I am concerned, this is the craziest year I have ever experienced with this insect, and I have worked with the @&#*# beasts for 30 years now! On one site where we collect samples regularly, we found mostly large larvae and pupae in one section of the fairway, and 30 yards further down the fairway, the insects were mostly adults and tiny larvae. Go figure!

For western Massachusetts, most of the ABW are in the adult or small larvae stage now. You might hold off (again until things dry out a bit) and use a curative treatment (e.g., Dylox™) about a week from now in areas where you see the tell-tale wilting. In other locations - it's impossible at this point to project what is going on! You will have to monitor your own areas and determine which stages are most prevalent, and act accordingly.

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.

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