Lawn Pests and Diseases

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Just what are those little cream-colored moths flying up out of the grass? Everyone seems to think that they are the adult sod webworm moth. They aren’t. These small moths are the mature adults of those little green worms that totally defoliate the boxelder trees and they will not damage your lawn in any way. Nor will the mosquito-like gnats that fly up out of the grass when you mow, damage your turf. If you notice either of these pests, ignore them. They are just out enjoying your yard.

The actual culprits that damage your lawn hide much better and are less conspicuous. White grubs (the larva of June beetles and billbugs) and sod webworms (the larva of the lawn moth) are the most common destroyers of turf. The adult beetles and billbugs deposit their eggs in the soil in June and early July, which hatch out shortly thereafter, and start nibbling on the roots of the grass. Sometimes they damage the lawn so severely that large brown patches will begin to appear, and no matter how much you water, the spots keep turning brown. The best way to determine if you have grubs is to cut a 12 by 12 inch triangle in the turf where it has been damaged, and pull up on it. If it comes up easily, like someone has been through with a sod cutter, and you discover little white worms underneath, you have grubs.

Lawn moths fly over your lawn at night, usually in July and August, dropping eggs into the grass as they fly. When they hatch out, the webworms, unlike white grubs, do their damage where the grass emerges out from the soil. They will quickly chew the stem off and move to the next one. Almost always, where you notice the damage, you will find a sticky, web-like cocoon (hence the name webworm), where they find shelter from the heat. Mach 2, Dylox and Merit granules have proven effective. It will take a few weeks to a month for your lawn to recuperate after insect damage, so have some patience. It won’t green back up instantly after you apply an insecticide.

Did you have problems with grubs eating your lawn last year? Adult grubs winter-over deep in your lawn, hibernating until warm weather wakes them, then they work their way to the surface and make a meal out of the roots of your grass. Because of the wet weather during spring, the damaged grass still appears healthy and green. Only when the weather turns hot and dry does the turf start to stress, and the patches begin to appear–long after the damage has been done. March and early April usually are the best time to control the grubs BEFORE they damage your lawn. Merit and Mach 2 are the best products available used to combat these invaders. One application will effectively control grubs and other root attacking insects in your lawn all year.

If you still have dead patches and you haven’t found evidence of either of these pests, then you might have a lawn disease. With all the wet weather, mixed with hot and cool temperatures during the spring, numerous diseases spring up in the lawn. The best thing to do (if you think you have a disease) is to take a sample to the Extension agent or a local nursery (like us) for diagnosis. Luckily, most diseases can be controlled with a general purpose fungicide such as Daconil or Copper Sulfate.

Your best defense against insect and disease damage in your lawn is proper watering and fertilizing habits. Many gardeners kill their lawns with kindness. When the weather turns hot, a gardener’s instincts tell him or her to water more often. A lot of people water every day for 15 minutes in hot weather, even twice a day sometimes. How deep do you think the water can penetrate most soils in 15 minutes? Not very deep. This form of watering encourages shallow roots and weak grass that turns brown in the summer even if you do water it every day. It has no capacity for water storage and burns easily. By watering less often (such as every 3 days) and for longer periods of time (45-60 minutes per station) your lawn will develop deeper, stronger roots that will find the water it needs deep in the soil when the weather turns hot.

A consistent fertilization program (about every 6 to 8 weeks) will also keep your lawn looking its best. An application of a slow release nitrogen or a combination fertilizer 4 to 6 times a year promotes a healthy, green, thick lawn that requires less water and resists insect and disease damage. Although you might have to mow a little more often (and always remember to mow high, especially during the hot summer months, about 2 to 2 1/2 inches), it will be well worth the extra work.