This is USU Extension Horticulturist Tom Beddes based in Utah and Juab counties.
In the summer, the lawns often develop brown spots. While it's often assumed to be due to drought stress, there are many other causes like lawn-feeding insects and fungal diseases.
To determine whether drought stress is the cause of your brown spots, stick a long screwdriver into the soil and the brown areas. If the screwdriver penetrates easily to the hilt, the brown spots are probably adequately watered.
You must also check the brown spots for lawn-feeding insects. The most common are grubs and sod webworms. This year lawn grubs will be active until late July to early August. But sod webworms can be active the entire season until October.
To check for them try pulling on the grass and a brown area. If it easily comes up without roots, it's likely due to insects. If brown areas receive adequate irrigation and the dead grass is still rooted though, you can send a sample to the Utah State University Extension pest lab at theUSU Extension pest Lab.
The past lab will provide what information they need including the type of sample so that they can best help you.
