You Are Here: Management Updates 2002 Archive April 26, 2002

Date: April 26, 2002
Category: Insects
Subject: White Grubs, Hyperodes Weevil

We continue to receive numerous reports of white grub activity throughout the Northeast. European chafer grubs are causing significant damage in many regions, including areas where they had previously not been reported. Home lawns, athletic fields, and roughs of golf courses have sustained severe damage, as have some pastures and hay fields. The long time "hot spots", such as the North Shore of Massachusetts, southeastern New Hampshire, and Capital District of New York are experiencing major damage from grubs directly and from secondary pests, such as skunks and raccoons. (We are also getting samples from other areas including the other usual suspects, Japanese beetles, oriental beetles, and asiatic garden beetles.)

European chafers thrive in dry conditions so we suspect many areas were attacked last fall but homeowners or turf managers may have mistaken the damage for drought stress, following the hot dry summer of 2001. When grubs returned to feed in the spring of 2002, they destroyed the previously weakened turf.

For the short term, an application of trichloron (Dylox or Proxol) is the only treatment alternative. It is probably too late in most locations to derive much "success" from such an application, and it is difficult to justify economically in many cases anyway. Meanwhile note that trichlorfon is NOT labeled for use in Maine. Try to manage the damage for now (roll areas that have been torn up), and remember that grubs will remain active for about four more weeks before they begin to pupate. (Based on this spring's plant phenology, this is only a guess. My colleague, Paul Heller, at Penn State University, tells me that one indicator plant we often use to predict European chafer pupation is already in bloom in Pennsylvania, so perhaps the chafers will be ahead of schedule as well.) So if you plan to overseed or renovate, you might want to wait until the grubs have finished feeding (usually late May or early June).

Annual Bluegrass Weevils: The spring weather has been a real roller coaster and we do not yet know the final impact on the annual bluegrass weevil ('Hyperodes' weevil). We know the adults have been moving out of overwintering sites since the first week of April, and we expected some of them to reach the fairways and greens last week and begin to lay eggs. But then we had the cold weather. Our best guess right now is that the cold weather simply stopped them in their tracks (Frank Rossi suggested a "red light - green light" scenario), and that as the weather warms again, they will resume their trek.

For golf course superintendents in southern New England and metropolitan New York, we appear to be in the middle of the optimum time to apply a protective application. You can use Dursban (the label limits each application to 1 pound AI per acre but there is no limit to the number of applications), or you can use any of the synthetic pyrethroids labeled for use on golf courses. Follow with a light watering (one or two passes of the sprinkler should do it). Those in central and northern New England should try to delay applications until the middle of next week (say around May 1st).

Are you as confused as I am? Here in Amherst, we have Forsythia still in full bloom, alongside flowering dogwoods ... and the beat goes on.

- Submitted by: Dr. Pat Vittum