On lawns with a history of white grub damage and where preventative-type insecticides are used, the best time to apply these insecticides is from the third week of June to mid-July. Insecticides for preventative grub control include Chlorantraniliprole, Imidacloprid and Halofenozide. Preventatives are normally used on areas that have had a history of grub problems. Traditional grub insecticides such as Dylox are normally applied in late July after grubs are present or as a rescue treatment once damage is seen. Products that contain Merit (imidacloprid) or Mach 2 (halofenozide) are considered grub preventers.

Actually, neither product prevents grubs, but rather they kill grubs when they are quite small, and long before they cause damage. Merit and Mach 2 are safer to use around pets and humans than traditional grub killers. Remember, all grub products must be watered in before they are activated.

Squash bugs

Squash bugs are the grey, shield-shaped bugs that feed on squash and pumpkin plants. If you have had problems with these insects in the past, you know that they are almost impossible to control when mature. Non-chemical control would be a daily search of the copper-brown egg masses that are laid on the underside of the leaves. Adult squash bugs have a hard body that an insecticide has difficulty penetrating. Thus, chemical spraying when the insects are small is important.

We are now seeing the nymphs of the first generation. These nymphs will eventually become adults, which will lay eggs that will become the second generation. The second generation is often huge and devastating. As each new generation hatch, the population just explodes! Therefore, now is the most important time to control as many squash bugs as possible.

Because squash bugs feed by sucking juice from the plant, only insecticides that directly contact the insect will work. General-use insecticides such as permethrin (Bug-B-Gon Multi-Purpose Garden Dust, Green Thumb Multipurpose Garden and Pet Dust, Bug-No-More Yard and Garden Insect Spray, Eight Vegetable, Fruit and Flower Concentrate, Garden, Pet and Livestock Insect Control, Lawn & Garden Insect Killer), malathion, rotenone and methoxychlor provide control if a direct application is made to young, soft-bodied squash bugs. This means that you MUST spray or dust the underside of the leaves because this is where the insects live.

Lawn weeds

Ask homeowners about their No. 1 lawn concern, and the usual reply is "weeds." But most homeowners are too narrow in their approach to controlling weeds. When someone asks, "How do I control weeds?" they usually mean, "What product do I spray?" Although herbicides are an important tool for controlling weeds, they are only a part of a total weed control program. The best defense against weeds is a dense, healthy, vigorous lawn, which can only be obtained through proper fertilizing, watering and mowing.

Many Extension publications discuss both cultural and chemical control of weeds. For more depth on the cultural practices that are an integral part of a weed control program, see the Kansas State Research and Extension publications "Fertilizing Kansas Lawns," "Watering Your Lawn" and "Mowing Your Lawn."

Weeds are opportunists, taking advantage of open spaces in thin, weak stands of turf. Although improper fertilizing, watering and mowing are the most common causes of poor lawns, insects and diseases also can expose the lawn to weed invasion. Always try to determine why weeds invaded the lawn, and correct the problem. If the basic cause is not corrected, weeds will return even though existing weeds may be eradicated with herbicides. Understanding the basic concepts of weed control are important for weed-free lawns. For application information, cautions and restrictions, refer to the label directions on the product container.

Controlling annuals

Cool-season grasses, such as annual bluegrass, annual bromes and little barley germinate in early fall after spring-applied pre-emergence chemicals are no longer effective. If these weeds are a special problem, additional fall applications may have to be used about late August through mid-September. Annual broadleaf weeds such as chickweed, henbit and shepherd's-purse are also winter annuals that germinate in the fall. Knotweed germinates in late winter or very early spring, often in February under snow cover. The appropriate pre-emergence herbicide should also be applied by mid-September for these weeds. Annual bluegrass begins germination earlier and requires pre-emergence application by early August. Germination may also occur through early spring.

Make sure the product you choose is labeled for the weeds you want to control. Special note: If overseeding or seeding a lawn in the fall, many of these products will also kill the seeded grass as it begins to germinate. Application of a herbicide prior to seeding is often not recommended unless the product label specifically states that is can be used.

For more information or assistance on this or other topics, please call the Extension Office at 272-3670, located at 501 S. Ninth St.