Check 1: the tug test
Grab a handful of the brown grass at the edge of the patch and pull. If it peels back like a loose carpet, something has eaten the roots. Look in the top inch or two of soil for white, C-shaped grubs. Ohio State University Extension calls this the quickest way to check for grubs.
If the grass stays put and the roots hold, it is not grubs. Move on to check 2.
Check 2: the screwdriver test
Push a long screwdriver into the soil in the brown area, then in a green area. If it goes into the green area easily but fights you in the brown one, the soil is dry and the grass is most likely drought-stressed or dormant. Dormant grass turns straw-colored, starting in the sunniest and driest spots: slopes, the strip along the driveway and areas over shallow soil. Footprints stay pressed into it long after you walk across.
Dormant grass is not dead. It usually greens back up within a couple of weeks of steady rain or deep watering.
Check 3: the shape of the damage
- Irregular patches that lift like carpet, with animals digging: grubs. Skunks, raccoons and birds tearing up the lawn are often the first sign.
- Broad, even browning in the sunniest and driest areas: drought.
- A round dead spot with a dark green ring around it: dog urine. The ring is the extra nitrogen at the edge.
- A sunny patch along a driveway or walk that keeps spreading and does not recover with water: possibly chinch bugs.
- Circles or small spots that show up after hot, humid nights, with lesions on the blades: a lawn fungus such as brown patch or dollar spot.
- Shredded, white-tipped blades or scalped high spots: the mower. A dull blade tears grass, and cutting too low scalps it.
How many grubs is too many?
A few grubs are normal. To count them, cut three sides of a one-foot square of sod with a spade, fold it back and count the grubs in the soil and roots. Ohio State’s guideline for the common annual grubs is about 10 per square foot before control is usually needed. A healthy, well-fed lawn tolerates more feeding than one that is already stressed.
What to do about each
- Grubs: treat the current grubs, reseed the bare areas in fall, and put prevention in place for next year. Preventive products go down between late May and mid-August, depending on the product. Annual grub prevention is part of our standard lawn care package.
- Drought: water deeply when you water, mow high (3 to 3.5 inches) and hold off on feeding grass that is dormant. It will come back with rain.
- Dog spots: water the spot right after the dog goes to dilute it, and reseed spots that do not recover.
- Chinch bugs: they need a treatment aimed at the insects; water alone will not fix it.
- Fungus: water early in the morning rather than in the evening, so the grass dries before night, and mow with a sharp blade.
- Thin, patchy lawn after any of these: plan on fall over-seeding and core aeration.
Still not sure?
Text a photo of the patch to 440-840-5018 and ask. A close-up of the grass and a wider shot of the area help.