KC Gardens

Time to control grubs

Grub on table

Tip of the Week

Summer officially begins June 21, which means less rainfall and warmer temperatures. The arrival of summer also signals that it is time to be proactive and prevent one of the most destructive lawn pests, grubs. White grubs feed on the roots of all commonly used turfgrass species. As a result of their feeding, the grass plants cannot cope with the stresses of summer and die. Oftentimes the grass dies, leaving you with large dead patches of grass in the late summer. Prevention of grubs is the key to proper control.

The most common approach to treatment is to apply a preventive application. This chemical is applied prior to the grub hatch and feeding. The preventive treatments then are in place in the grass roots ready to kill the young grubs as they start to feed. The next couple of weeks are the ideal time to apply grub control. That allows time for it to be up taken by the plant and ready to stave off damage when grubs hatch, usually in early August.

Consider grub treatment as insurance for your lawn. If you have had grub problems in the past you are likely to experience the same results this year, so treatment is recommended. If you don’t like the idea of making blanket applications of pesticides then consider this — shade areas in the lawn are seldom bothered by grubs. They prefer to lay their eggs in the warm, sunny portions of the yard. The adult stage of the white grub is the common brown June bugs seen buzzing around patio lights.

Preventive grub control products include imidacloprid (Merit) and chlorantraniliprole (Scotts GrubEx). These products have a long residual activity and require only the one, early summer application.

Insecticides should be watered in, or the application can be timed with forecasted rain. Ideally, this is within 24 hours of application. Watering in the product serves several purposes. Irrigation activates the chemical and moves it into the soil. Grubs feed within the root zone, not the soil surface, so the product must be moved past the turf crown and thatch, into the feeding zone. This also gets the product out of direct sunlight, which can lead to photo degradation and reduced effectiveness. If the ground is especially dry, irrigation prior to application will move grubs closer to the soil surface and insecticides.

As long as I have you thinking about your lawn, remember these tips for summer lawn care:

• Cut high and let it lie: Mow bluegrass and tall fescue around 3 – 3 ½ inches and zoysia at 1 ½ inches. Let grass clippings fall back to the ground to return nutrients to the turf. • Irrigate deep and infrequently. Soak the soil to a depth of 6 – 8 inches and then do not water again until the turf shows signs of needing it. • Keep those mower blades sharp! Rule of thumb is to sharpen after every 10 hours of use.


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