It's a good time to scout turf areas for white grub populations. You may not have seen many of the adult beetles, but conditions were ideal during egg-laying, especially during a year like this one when soil moisture has been plentiful.

You may find Oriental beetles, Japanese beetles, masked chafers, Asiatic garden beetles, or Green June beetles, depending on your location. These beetles lay their eggs in the soil and successful hatches depend in part on soil moisture. We have had plenty of that.

It's a good idea to look under the turf in untreated areas so you aren't taken by surprise in September or October when large grubs could potentially cause a lot of damage. Turf that is growing well with plenty of moisture can support grub-feeding without symptoms.

If things dry out in the fall, the damage will quickly worsen. In the early stages of feeding, the turf won't "pull up like a carpet," so you will need to cut some squares and inspect the root zone.

If you find high numbers of white grubs in early September, you can still treat them with products containing imidacloprid or clothianidin, but it's too late for Acelepryn. Dylox and Sevin can also be used.

Beneficial nematodes are also an option, especially when the soil is wet. In all cases, follow label directions to water-in the treatment after application.

Irrigate with around one-quarter-inch of water immediately after treatment (or timely rainfall) to leach the insecticide into the root zone where the grubs are feeding. Irrigation also increases insecticide contact by drawing the grubs closer to the surface.

If the soil is very dry, irrigation one day before treatment increases efficacy by bringing grubs closer to the surface and reducing thatch binding and evaporation of liquid treatments. Do not apply soil insecticides to saturated soil.

Granular formulations need to be applied to dry grass to allow the granules to sift down into the thatch. Liquid and granular applications are equally effective, but granular formulations are more forgiving if post-treatment irrigation is delayed. Read instructions on insecticide label carefully.

For best results with any insecticide, mow the turf and rake out dead grass and thatch before treatment to reduce the amount of insecticide bound up by surface debris. If the thatch layer is greater than a half inch thick, consider removing it with a dethatching machine before applying a grub treatment.

Good turf management (proper irrigation, fertilization, mowing) results in vigorous turf with a deep, extensive root system that can tolerate higher grub densities without showing damage.

While grub-resistant turfgrasses do not exist, species with a deeper root-system and higher heat-drought tolerance are generally more tolerant of grub feeding. Among the cool-season grasses, tall fescue is the most tolerant species and perennial ryegrass the least tolerant.

Watering during peak beetle activity in summer tends to attract egg-laying females, especially when the soil in surrounding areas is dry, and increases survival of eggs and young larvae. In late summer and fall, however, irrigation makes the grass more grub tolerant.

"Growing Green" is contributed by Lehigh County Extension Office Staff and Master Gardeners. Lehigh County Extension Office, 610-391-9840; Northampton County Extension Office, 610-746-1970.