And the fun begins
Annual bluegrass weevils (ABW) got off to a slow start this spring in most of New England. Forsythia only began to show “half green-half gold” (HGHG) about a week ago in the Amherst area, and Bradford pears were showing a similar “half green-half white” as the leaves began to emerge. Normally we recommend that an adulticide be applied between Forsythia HGHG and full bloom of flowering dogwoods Cornus florida), and usually there is a 10- to 14-day period between the two. But this year the Forsythia on campus were just reaching HGHG at the same time that dogwoods exploded into full bloom, seemingly overnight. So some locations had about a two day window for that adulticide!
The folks in southern New Hampshire appear to be about a week behind us in Amherst. Forsythia was still in full bloom, azaleas were in peak blossom, and daffodils were still in full bloom on Saturday (May 11th) just east of Concord. So golf courses in similar settings are probably still too early for an adult treatment.
Further complicating matters has been the steady rain we have had throughout most of April (nearly 9 inches in some areas, triple the average) in most of southern New England. We had a brief break in the precipitation for a few days, but are back to steady rain for the next couple days. Presumably the rain is keeping soil temperatures from warming up, so ABW populations are getting off to a slow start.
Most of the samples that came in to our lab last week for the Weevil Trak monitoring program are only adults so far. There is no sign of any young larvae emerging yet, and I don’t expect to see any larvae for another couple weeks from the sites we are monitoring in Massachusetts. Of course, if we get a stretch of warm weather (highs in the mid 70s), that could change quickly, as everything is driven by temperature. In previous years we were already seeing tiny larvae in some of the warmest locations by the middle of May in warm years, but that is not happening this year.
Those of you in most of Massachusetts (other than the hills of Worcester and Berkshire Counties, which are usually markedly cooler) should aim to apply an adulticide as soon as possible, if you have not already done so. Keep an eye on those temperatures. If it warms up, things will begin to “pop” quickly.
Stay tuned – the next indicator to watch for is Rhododendron catawbiensis full bloom, a good time to apply a larvicide. At this point it seems like that will be at least a week or two from now, maybe even more!
Submitted by: Dr. Olga Kostromytska and Dr. Pat Vittum
