Answer: The best way to find out what's going on with your lawn is to dig into the area and inspect the soil. Sod web worms will leave webbing on the grass blades close to the soil; grubs will be found an inch or two below the top of the soil. If you've treated for grubs, you probably won't find any, but you may find other pests. A large population can turn the sod brown, but so can fungal diseases or dry soil. Cool season grasses will brown out in the summer but green up when the weather cools. You might want to take a turfgrass sample to your local cooperative extension office for inspection. Helpful folks there can determine whether the browning is a result of disease or insect feeding.
Best wishes with your lawn!
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