We have received our first report of grubs in a lawn south of Boston. The grubs were first instars (very small) and the lawn has been irrigated throughout the summer. This makes sense to me. As noted earlier, we should see nearly normal development of grubs on irrigated turf this summer, and first instars usually start to show up in early to mid August. Now would be a good time to start looking in your usual trouble spots, to make sure that any preventive applications you made earlier in the year are working.
The dry conditions that continue to be widespread throughout southern New England may result in a delay in egg-laying by the adults of the various white grub species we have. So if you scout those areas now, you may get a false sense of security if you don't see any grubs. Eggs may not be laid for another week or two, which of course means that the small grubs won't be apparent until the early part of September. So start monitoring those unirrigated areas next week, especially concentrating on the areas that hold moisture a little bit better. Be prepared to apply a curative product if necessary - but wait until the grass is growing again. (Remember that many of the preventive products rely on being taken up into the plant, but that can't happen when the plant is in summer dormancy.)
As mentioned in previous posts, chinchbugs and billbugs have been active in many locations this summer. Turf that appears to be in summer dormancy will not recover in September if it has been killed by chinchbugs or billbugs.
Another culprit that appears to be causing some damage in some lawn-type turf is sod webworms. Some areas appear to be parched (even crinkling dry, brown - in other words, dead) with evidence of holes in the turf where birds have been pecking. If you monitor the area and find small caterpillars feeding, there are several insecticide options that can be used to reduce their activity. If the caterpillars are more than 0.5 inch long, it may be difficult to get significant levels of control at this point. (There are several different species of sod webworms, and adults have been flying in the evenings for the past couple weeks in western Massachusetts, so presumably they have been active elsewhere too!)
Submitted by: Dr. Pat Vittum