You Are Here: Management Updates 2006 Archive June 29, 2006

Date: June 29, 2006
Category: Insects
Subject: Annual Bluegrass (Hyperodes) Weevil, White Grubs

Annual bluegrass weevils
My "antennae" are picking up reports that some golf course superintendents in the Northeast are being encouraged to use Arena™ (chlothianidin), a relatively new product that is chemically related to Merit™ (imidacloprid) to control annual bluegrass weevils (ABW). Our field data from trials conducted earlier this year suggest that Arena is inconsistent at best against the annual bluegrass weevil. While we have not yet completed the statistical analysis, the numbers show that there was a 37% reduction in larval populations in an Arena plot that was treated in mid-April (and sampled in early June) compared to the untreated check, and a 78% reduction in populations in a plot that was treated in early May and sampled in early June.

There are many questions that still need to be answered about this product on ABW - what is the ideal timing? does it reduce populations consistently? will it work in the heat of summer? I tend toward being conservative, so until we have answers to these questions based on non-biased field trials, I would urge caution. Keep in mind that the product is chemically related to Merit™, which has proven to be very inconsistent against ABW over the years.

Having said that, Arena™ looks very promising against the various white grubs, and appears to have a longer period during which it can be applied successfully. In addition, reports from some university colleagues indicate that it may be more effective against chinch bugs and a variety of other insects than is its cousin, Merit™.

We are now in that period where you need to monitor areas where ABW have been active. Check some of our updates from last year for more details, but briefly:

If most of the insects are in the adult stage, treat the affected areas with something that stays in the thatch (e.g., Dursban™ or a pyrethroid).

If most of the insects are pupae, wait a week and then use Dursban™ or a pyrethroid.

If most of the insects are larvae and have not begun to pupate, you may get some relief with trichlorfon (Dylox™). We have also had success in previous years with spinosad (Conserve™) but the results this year have been inconclusive.

White grubs
Just a reminder - we are now in the period of time when an application of imidacloprid (Merit™) should be very effective against most white grubs. The European chafer adults are flying now and laying eggs, and oriental beetles have been out and about in some areas for a week or two. So now is a good time - remember to wait until the soils dry out a little if you are in an area that has been inundated with rain, and then water in (with at least 0.1 inch).

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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