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Management Updates

This section of the web site features Management Updates written by the turf specialists of the UMass Extension Turf Program. The messages cover regional problems, are geared toward regional conditions, and are posted frequently during the growing season.

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Rainfall and Turf Insects

Jul 30 2018

What about all the rain ?!?!?

Some folks have been asking me how the turf insects are being affected by all the rain we have seen in Massachusetts. While some parts of northern New England apparently have been notably drier, western Massachusetts and much of Connecticut has seen a lot of rain over the past couple weeks - 10 inches or more in some places. So below is my best guess as to the impact of all that water on insect activity and insecticide performance:

White grubs - Since temperatures have been normal or higher than usual in some places, I believe most grub species are following their "normal" schedule for egg laying and grub hatch. That means adults are laying eggs now, and may continue to do so for a few more weeks. (Most egg laying should be done by the middle to end of August.) In areas that have received a lot of rain, you should look for grubs to hatch in higher areas or areas that drain better (sandier soils). Turf managers who applied a neonicotinoid in June or early July and experienced a rain event that delivered three or more inches of rain in a period of 48 hours should monitor the treated areas starting in the second week of August. (My concern is that the high rainfall may have moved some of the product beyond the root zone. This is just a supposition on my part, not based on any data, but you might want to keep an eye out for some grubs hatching in treated areas.)

Chinchbugs - Chinchbugs are active throughout the summer months. While some studies initially suggested that they thrive in hot, dry conditions, other studies indicate they do well in wet conditions. In any case, they are active in the summer months. The damage often resembles summer dormancy, and is often misdiagnosed until September, when the dormant grass begins to recuperate. Many of the lawns in the areas where rain has been heavy are still green (one benefit to all the rain!), and not showing dormancy. Turf managers may be lulled into a sense of complacency but chinchbugs may be active in these lawns. So if you have a history of chinchbug activity, get out and monitor now to see whether chinchbugs are present. (A pyrethroid will reduce populations considerably.)

Billbugs - Like chinchbugs, billbugs are active and cause damage during July and August. They should mostly be in the larvae stages, active in the thatch and crown. The damage often resembles summer dormancy and can be masked by turf that has plenty of moisture. So get out soon and take a look to determine whether billbugs are present. The bad news is that billbug larvae are very difficult to control, but you can manage the damage by raising the mowing height, and consider renovating the areas to incorporate cultivars of perennial ryegrass and some of the turf-type tall fescues that have endophytes.

Caterpillars - Black cutworm activity remains steady throughout the region. I have seen some sod webworm adults flying in recent weeks, but I have never noticed a correlation between heavy adult flights and heavy caterpillar activity. So just because you see lots of moths, there is no guarantee that there will be lots of caterpillars. As with all the others, get out and take a look. (A soapy flush will bring up larger caterpillars quite quickly, but may underestimate the total population since some of the younger caterpillars will die on the way to the surface. Remember to rinse the flush with clear water, and do not flush on a hot, sunny day because you may burn the turf.) Caterpillar activity appears to be relatively unaffected by the wet weather we have seen so far this summer.

Annual bluegrass weevils (golf course only) - Like the other insects, the steady rain has provided plenty of moisture for the turf so if you have managed to avoid the various summer pathogens, the turf may be masking ABW activity. Monitor throughout the next several weeks to determine whether you have larvae feeding. The medium-sized larvae will be found above the crown, in the thatch, but the larger larvae will be deeper in the profile, often in the crown. Remember that large larvae are very difficult to control, and pupae only respond to a sledgehammer! If you find small larvae, you may get some relief with one of the larvicides. Cyantraniliprole would be one option that would help reduce ABW populations and give you control of white grubs as well. Other larvicides include indoxacarb and spinosad. If you are seeing adults moving on the surface, you can apply a pyrethroid (only if you do not have pyrethroid resistance) or chlorpyrifos. But remember the summer adult applications are usually much less effective than spring applications, and you run the risk of accelerating the development of resistance in the population.

Crane flies- Most of the New England crane fly populations are Tipula oleracea, the "common" crane fly. This species has two generations per year, with one of those generations feeding actively as larvae throughout the summer months. (Both species pupate in late August to mid September.) Crane flies do better in wet conditions, so it is likely that our crane flies are liking the wet conditions we are seeing in much of southern New England so far this summer. That means that we are likely to see a higher percentage of the larvae surviving, which translates into more adults flying in late summer. Check for evidence of crane fly feeding now in the root zone or in the thatch. (The larvae look like wriggly brown caterpillars but are much more active than most caterpillars, and the damage can resemble grub damage.) And watch for adult flights in late summer.

Submitted by: Dr. Pat Vittum