Why is my lawn turning brown? Learn the difference between heat stress and Chinch bugs
Updated: Mar 24
When the mercury tops 90F, the humidity is off the charts and there’s not a rainy day in sight, you take yourself to the pool or, if you’re lucky, to the shore. Your lawn and garden don’t have those luxuries, however, and must stand and take the brutally hot conditions. Anything that provides your grass and landscape plantings with some relief will have to come either from Mother Nature or from you.
Your lawn and heat stress
August is traditionally a brutal time for your home landscape. Temperatures are routinely averaging in the above-80F range going into the second consecutive month. Rainstorms are unpredictable as always. And when it does rain, it’s often a deluge of a storm, dumping way more rain than can be absorbed by the ground. Excess water flows off into ditches and away from the plants on your property that need it for growth.
And despite the storms, the lawn and landscape are using more water than the ground has available. This results in heat stress. Oftentimes the progression from happy to heat stress in the landscape happens right under our noses without us even noticing.
Signs of heat stress
The next time you pull up to your driveway or take the trash to the curb, stop a minute to scan your property and take in what you see, from the grass in the yard to the perennials edging the drive to shrubs and trees surrounding the home. The telltale signs of damage due to prolonged heat stress will be:
Leaf blades that begin to curl.
Fading color in the lawn from green to light green to brown—either just at the tips or the full blade—especially in full-sun spots.
Footprints that stay in the lawn rather than the grass rebounding.
Trees, shrubs and perennials symptoms
Leaves that are wilting, yellowing or even looking burned around their edges.
Rust-colored spots and/or bumps on the leaves.
Sap trickling down the tree’s trunk.
No new or healthy seasonal growth.
How to treat and prevent heat stress
Since the cause of heat stress is lack of water during times of prolonged heat, watering the lawn, tree and perennial plantings will go a long way to bringing your yard back to life. But don’t just wave your watering wand over the lawn for just a few minutes each day. These short-lived watering sessions promote a shallow root system, and shallow roots cannot properly search out the ground’s water reserves during dry spells.
Deep watering your lawn and trees
Water your lawn and plants deeply two to three times per week. An oscillating, rotating or impulse sprinkler can do the heavy work of long and deep watering. You should water a section of your lawn for at least 15-20 minutes at a time to ensure proper absorption. For trees, be sure you water under the entire tree, from just beyond the trunk to the “drip line,” or where the canopy shades the ground. A soaker hose is best for under trees as an oscillating sprinkler will waste too much water by hitting leaves and branches.
Try not to walk on your dry lawn during heat stress
Walking on a dry lawn is also a stressor. Try to find other ways into your home or around the lawn rather than walking directly on it.
Don't fertilize if your lawn is stressed
If your lawn is still stressed at the time of fertilizing, eliminate or push back the feeding until the lawn has regained some of its previous vigor.
It may be time to consider an irrigation system
Watering and watching, and watering and watching. That's a lot of time and energy you're spending and you'll feel it again when you receive your water bill. A sprinkler or irrigation system could save you both. See our irrigation system pros and cons list.
OK, but maybe it’s Chinch bugs
Are you doing all you can do — watering long and deep two to three times a week? Not walking on the lawn? Following your lawn feeding regimen to a T?—and still finding that your lawn is browning in spots? Maybe it’s not heat stress after all. Maybe its Chinch bugs.
Chinch bug identification and life cycle
The Chinch bug (Blissus leucopterus) is a native North American insect that feeds on the stems of turf grass and grain crops. The insect is very small—less than ¼-inch long when fully developed—and therefore not very noticeable. The adults vary in color from dark red to brown. Its wings are white and its legs are red. The distinguishing characteristic of the nymph stage—which is about half the length of the adult—is a white band found across its abdomen.
Chinch bug adults emerge from hibernation in March and April, when they begin to mate and lay eggs into early summer. These adults begin feeding on grass and grain crops, and as the nymphs develop throughout the summer, they, too, begin to feed as adults. The first generation of adults then die and the new generation will hibernate in hedgerows, road sides, woodlands and even under the thatch of your lawn during the winter.
Chinch bugs feed on plants in the grass family, which include economically important crops such as wheat, oats and corn, as well as turf. They prefer hot, dry and sunny conditions. Heavy rains will pin nymphs into the ground and kill them, while generally moist and humid conditions promote the growth of a fungus that feeds on and kills the adult. They also have a few natural predators, including the big-eye bug and the tiny wasp.
Signs of a Chinch bug infestation
Dry brown spots in a lawn can indicate a feeding chinch bug population. These spots can start small and then spread. This happens because the chinch bugs are essentially sucking the “juice” from a grass blade until it is dry, then they move on to the next grass plant. The sucking action also can release a toxin from the chinch bug that can kill the grass plant. These brown spots can look a lot like poorly watered turf. Properly watered grass that still has brown spots can be a sign of chinch bugs.
Do this first: How to know if it's heat stress or Chinch bugs
You can check for the presence of chinch bugs by getting on your hands and knees in a location where the brown spot of grass meets with the greener grass. Part the grass enough to see down to the base of the grass plants. If chinch bugs are present, you’ll see the tiny dark-red to brown bugs moving around near or attached to the base of the grass. A magnifying lens may be helpful here.
Another way to check for the presence of chinch bugs is to cut a plug of grass from that brown-green grass intersection with a knife (an apple corer may work, too!). Place that plug of grass into a bucket of water. If present, the chinch bugs should float to the top.
How to prevent a Chinch bug infestation
The best prevention of a chinch bug infestation is keeping to a regular lawn maintenance program. That means regular mowing, fertilizing and especially irrigation. A healthy, non-stressed lawn grows fast enough to outpace any damage from chinch bugs.