You Are Here: Management Updates 2007 Archive June 19, 2007

Date: June 19, 2007
Category: Insects
Subject: Annual Bluegrass (Hyperodes) Weevil

Unbelievable!!! That is about all I can say. We have seen the highest populations in at least 20 years on virtually every golf course in the Northeast. Some courses are reporting damage for the first time, others are experiencing incredible populations in their usual trouble spots. Some of the sites we have been sampling have had populations well over 200 larvae per square foot. Given that the threshold in the spring is generally considered to be about 30 to 80 larvae per square foot, these courses have considerable damage.

We are just finishing the counting of the samples we collected from our various field trials, and I have done some preliminary statistical analysis. Briefly, very few products applied during the traditional spring application window (between Forsythia and dogwood full bloom) "worked" very well this year. Most of them provided between 40 and 60% control of the populations. We don't know whether this drop off in performance is because the population levels were overwhelming or whether something else might be going on.

One phenomenon that seems to be fairly widespread this year, at least from New Jersey up through New England, is that there apparently were two distinct periods in the spring during which the adults laid eggs. Some adults became active during that warm stretch in late April or early May, and started laying eggs, while others did not get started until a couple weeks later. As a result, we are seeing two "flushes" of larval activity. We collect our samples using two-inch diameter pluggers, and on several occasions we have found at least one pupa and at least one tiny (need a microscope to confirm it) larva in the same plug. That is very unusual in June, because usually the first generation is reasonably well synchronized.

Those of you in Connecticut and points south should generally be done with the main damage from this first generation. However, because the populations were so incredibly high, you can expect to have additional activity throughout the summer. In most cases you should have a brief respite before the current new adults begin to lay eggs and you start to see the next generation larvae. For those of you in central Massachusetts and points north, you may still be seeing new damage - and lots of larvae.

Again - if you are still finding active larvae, hit them with trichlorfon (Dylox™) and water lightly. (Dylox™ is soluble so it does not need much water to get to the crown area.) I would suggest one or two passes of the sprinkler system. If you are finding mostly adults, consider treating the affected areas with a pyrethroid or chlorpyrifos (Dursban™). And if you are finding mostly pupae, wait a week or ten days and then apply a pyrethroid or Dursban™.

Good luck - it looks like it is going to be a wild ride for everybody!

And just to keep things interesting, I have had an unconfirmed report (from a very reliable source) of a green June beetle in South Deerfield, Massachusetts. And the oriental beetle adults started flying in Amherst earlier this week. Oh, goodie.

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. Trade names of materials are provided for informational purposes only and do not substitute for a thorough and careful reading of the label and application according to label instructions. 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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