You Are Here: Management Updates 2003 Archive June 24, 2003

Date: June 24, 2003
Category: Insects
Subject: What Impact is the Rain Having on Insect Development?

For those of you wondering about when you should apply imidacloprid (Merit™) for white grub control, do not apply the material when the ground is saturated. Most of Massachusetts has received heavy rainfall in the past few days and in most cases, the ground is saturated or nearly so right now. So hold off for a few days and let the soil dry out a little before applying any insecticide. In general the month of July is a good target date (the early half of the month for areas that have European chafers, the later half of the month for Japanese beetles), so don't feel you have to "jump the gun" yet.

Meanwhile I have received numerous telephone inquiries about annual bluegrass weevils (strictly a golf course problem). The development of this insect is the most unusual I have seen in many years. We collected samples from Westchester County, New York (just north of New York City) on Monday, 16 June, and are finding tiny larvae along side large larvae and pupae. As I said before, I think it will be extremely difficult to figure out timing of applications for the remainder of this season because the populations are already "spread out" - lots of different stages side by side. Having said that, my current projection for application dates for the second generation in southern New England would be sometime between 10 and 20 July. We'll know more as the current weather pattern (some heat and finally a break in the rain) progresses, and I will refine that projection early next week. But for now, figure on treating between 10 and 20 July. (Of course for those of you in locations further south, that target date will probably be just slightly earlier).

- Submitted by: Dr. Pat Vittum