White grubs are an insect that feed on the roots of grass. Lawn browning and areas that grow haphazardly are indications of a grub infection. When browning of the lawn is not solved by fertilization or watering, check the root level of the lawn where brown, wilted grass meets green grass for c-shaped white grubs, recommends the University of Illinois extension. There are several ways to prevent damage to a lawn by white grub damage.
Allow the lawn to dry out and go into dormancy during July to prevent the soil moisture needed for grubs to lay new eggs, recommends the University of Illinois Extension.
Mow, irrigate and fertilize the lawn regularly to keep the lawn healthy and prevent extensive damage by grubs, recommends the Michigan State University Extension. A healthy lawn is less likely to breed grubs.
Plant tall fescue grass as it is resistant to grubs damage, recommends Michigan State University. Seed fescue grass during the fall for a spring cover.
Cut a one foot piece of sod down to a two inch depth to inspect for grubs, recommends the University of Florida Extension. Early detection will reduce damage to the lawn.
Treat browning areas where grubs are detected with diazinon or trichlorfon (Dylox) insecticide to prevent damage, says the University of Illinois Extension.
Apply insecticides such as imidacloprid (Merit) or halofenozide (GrubEx) to prevent the growth and damage done by grubs. Insecticide application is best during late July, says the University of Illinois Extension, as this is when grubs lay their eggs.