You Are Here: Management Updates 2004 Archive July 9, 2004

Date: July 9, 2004
Category: Insects
Subject: Annual Bluegrass (Hyperodes) Weevil, White Grubs

Hyperodes - Still!
Most of the telephone calls I have received over the last ten days have been questions about the annual bluegrass weevil. While we have covered many aspects of the weevil in previous updates, I will try and review the "critical points" here.

Throughout the Northeast, populations are much higher this year than they have been in the past 15 years. Usually the first generation is pretty well synchronized, so that all the weevils are in about the same stage of development at the same time. However, this year there was a lot of variation as early as mid May, and that variation has continued. So now if you sample the turf, you may see tiny larvae, medium larvae, large larvae, pupae, and adults, all in the same small area. This makes it difficult to make decisions about control options.

We recommend that golf course superintendents scout the usual suspect areas regularly throughout June and July. Areas that experienced damage in mid June from larvae feeding are probably going to be vulnerable to attack with the second generation. Based on accounts from telephone calls, I believe many areas in southern New England are at a point where many adults are active on the surface right now. Adults can be seen walking on the surface, especially on sunny days.

In "normal" years good control can be achieved by targeting the adults of the second generation with an application of something that stays in the thatch, such as Dursban™ or a pyrethroid. This year a good target date appears to be between 5 July and 15 July for golf courses in most of Massachusetts and southern New Hampshire and Vermont. Points south of there may have already missed that window. In fact, golf courses around New York City may already be nearing the end of the second generation, believe it or not. Remember to water in lightly (one or two passes of the head.)

It all comes down to monitoring ... if samples show there are many larvae active in the thatch or crowns, you may get some relief with something that is very mobile and works quickly. Note that annual bluegrass weevil is not on the Dylox™ label, but given that company-supported field trials earlier this year looked very promising, we hope the insect will be added to the label soon. Also note that nothing will kill all the larvae, but usually you can bring the larval population below the threshold.

Larvae look like grains of sand with brown heads. Pupae are cream colored and diamond shaped. The wings are visible on pupae. If turf samples reveal that most of the insects are larvae, you may get some relief with an insecticide. However, if turf samples reveal that most of the insects are already pupae, you should delay - consider treating the area about two weeks later, when the pupae have completed their development and emerged as adults. (See previous updates for a description of a saline solution that is very effective at drawing larvae and pupae out of turf samples.)

As we have been saying all along, this will be one of the most confusing and confounding years for "Hyperodes" control in a long time. Keep sampling and stay tuned for more updates!

Grubs
Adults of all the usual suspects (Japanese beetles, European chafers, oriental beetles, asiatic garden beetles, among other) are out and about. European chafers have already begun to lay eggs, while the otherse will be following suit soon. With all the rain we have been seeing in many parts of the state, soil moistures are very favorable for egg survival, so the potential is there for an active grub season.

- Submitted by: Dr. Pat Vittum