The winter and spring in MA have been close to "normal" according to temperature data. Growing Degree Day (GDD) accumulation started in the second week of March and has been slow in the beginning, with relatively steady increases in mid and late March. GDD accumulations are not very different across Massachusetts, with both locations at 40 -50 GDD by mid-April. Many golf course locations in western and southern parts of the state are most likely to approach peak adult activity, and hence, a good opportunity for adulticide application, by last week of April – first week of May. (~100 GDDs).
For the most part, Forsythia has reached full bloom and maybe barely started to green up, indicating that the adults have started showing up on the short-cut grass. According to our observations, nine years out of ten, it is better to wait at least until Forsythia reaches that “half green – half gold” stage or and when Bradford pear is about half white blossoms and half green leaves. This seems to be about the right time to apply an adulticide, and as above, we expect that to line up with the peak of adult activity around the first week of May.
The first adults were observed on the short-mowed grass in late March, and now we are seeing a steady increase of weevil numbers on those areas. Remember the best timing for adulticides is when the following factors come together: adult activity increases, GDD accumulation is near 100, and Forsythia or Bradford pear is half-in-bloom-half-green… but we are not there just yet.
Monitoring of ABW adult activity is critical at this time to pinpoint the best adulticide timing, because these materials have short residual activity. Soap flushes, vacuuming, visual inspections of the greens, and checking clipping buckets after greens mowing can be used to detect peak densities of adults. If pitfall traps are installed, pay attention to daily catches to determine the peak. Monitoring adult activity is a great investment of time and effort even if an adulticide application is not in your plans. The peak of adult activity can also be a reference point for early larvicide application. If you plan to apply an early application of chlorantraniliprole (AceleprynTM) as a larvicide targeting small larvae feeding inside of the stem, the application should be scheduled 1-2 weeks after peak of adult activity.
Submitted by: Dr. Olga Kostromytska
