All of us have been commenting on how unusually cool this spring has been so far. Now I have the data to "prove it"!
Below is a graph that shows the degree day accumulation for the month of April for each of the last 10 years at Tumble Brook Country Club in Bloomfield, CT. The superintendent, Cindy Johnson, has been a cooperator with the Weevil Trak program each of those 10 years, and the data shown here are from a WatchDog data logger that was placed in the same location each year. So the temperature comparisons from one year to another give us a good look at what has happened over the years.
Tumble Brook CC Degree Day Accumulation 2009-2018
Two years (2010 and 2012) were unusually warm. Some of you will remember that we saw Forsythia in full bloom in late March in Amherst in 2012!!! Those years are reflected in the purple and rust-colored lines at the top of the chart. Meanwhile for comparison, 2018 shows up as the broad black line on the bottom. Most years we have seen a bit of a warm up in the middle of April, but that has not happened this year. (Forsythia has just reached full bloom in most of the Amherst area, a full month later than in 2012.)
Of course the warm weather we are experiencing today and tomorrow will result in a very noticeable increase in degree days so perhaps eventually this unusually cool spring will "even out" and catch up to other years. But for now note that the usual triggers for annual bluegrass weevil (ABW) activity are just beginning to occur in southern New England. We often consider 125 to 150 degree days to be the target for making an application targeting adults, and that often coincides with Forsythia "half green, half gold". At the very least you should be monitoring for adult activity at this point - soap flushes along the edges of your usual hot spots would be a good idea, and look for weevils on the surface on these warm, sunny days.
Avoid the temptation to treat too early. As Ben McGraw's work has shown, the earliest arriving adults take a while to become reproductively mature, so it makes sense to delay your application until a significant portion of the population has wandered onto the short grass.
Submitted by: Dr. Pat Vittum
