Brown Patches in Your Lawn?
How to stop the Japanese beetles that cause the problem
If you have brown patches in your lawn, I expect the cause is Japanese beetle grubs eating the roots of the grasses. Japanese beetles are out in full force, feasting on roses, linden trees and other favorite ornamentals, as well as puncturing and eating peaches, raspberries, blackberries and plums. Soon those same beetles will be landing on your lawn and depositing eggs in the earth. When those eggs hatch, hungry young larvae will begin feeding until fall when the soil cools and they burrow deeper in to survive the winter. Next spring those same larvae will crawl up closer to the roots of your lawn and resume feeding until they pupate and emerge as adults. The larvae are light gray with brown heads and curl into the letter C when disturbed.
The brown patches you are now seeing are from last year’s larvae that survived the winter.
Back when we lived in College Park, we did not have Japanese beetles. That’s because College Park was ground zero for the research that resulted in the development of the milky spore system of Japanese grub control. The developer was Dr. George Langford, chairman of the Department of Entomology. To test the effectiveness of the system, in the mid-1950s he treated all of the lawns within the city limits. A single treatment was highly effective.
When Clara and I moved to Deale in 1990, the lawn was full of mole tunnels. Moles love to feast on. Realizing the mole problem was due to a large infestation of Japanese beetle grubs, I treated the entire lawn with milky spore powder the summer of 1991. It took three years before I had 100 percent control. I have never had to repeat the treatment. Japanese beetles are flying around and feasting on our little leaf linden, and they are laying eggs in my lawn, but the milky spore is digesting the larvae as they hatch. The milky spore system of control is self-supporting once it becomes well established. It has now been almost a quarter century since I first used milky spore, and I no longer have moles tunneling nor dead brown spots in my lawn.
True, there are insecticides you can spread on your lawn that will kill the grub, but these insecticides have to be redone yearly. The use of them on lawns can also contribute to the pollution of the Bay. If you live near the Bay or its tributaries, do not use these insecticides; to be effective, they must be applied over the entire lawn.
Milky spore is available in two forms, powder or granular. The powdered form is measured using one-quarter teaspoon at three-foot intervals. The granular form is applied using a spreader. One bag of granular milky spore will cover approximately 7,000 square feet. Milky spore must be thoroughly and promptly soaked into the soil soon after being applied. Applying it just before a predicted heavy rain is best unless you have an in-ground sprinkler system that covers the entire lawn.
Milky spore can be used in the spring, summer or fall, but now is the best time because this is when the Japanese beetles are laying their eggs.
Milky spore is a good, safe and effective grub control system, but it cannot be used in conjunction with any of the other harsh insecticides recommended for grub control. Having Japanese beetles laying eggs in your lawn every year keeps the milky spore population alive and well.