Have you looked at your lawn in the Sioux Falls, SD area recently and noticed pale straw-colored lines where people or equipment passed? Those tracks are almost always heat tracking — a mechanical bruise to the leaf blades, not a chemical burn. Turf-science studies at Iowa State University’s turfgrass program and Michigan State University Extension show that heat tracking happens when slightly dehydrated grass is compressed by feet, mower tires, or spreader wheels during hot, sunny weather. The weight crushes cell walls and chloroplasts, causing blades to overheat and bleach within 24–48 hours. Fortunately, only the leaves are injured; crowns and roots stay alive, so the turf can make a complete comeback with the right care.

What exactly causes heat tracking?

1. Turgor loss: In hot, dry weather the water pressure (“turgor”) inside each grass cell drops.
2. Mechanical compression: Traffic across those weakened blades ruptures cell membranes and chloroplasts.
3. Thermal spike: With transpiration shut down, the damaged tissue overheats, dehydrates, and turns tan along the exact path of travel.

Researchers sometimes detect a harmless fungus called Ascochyta on the bruised tips. It feeds on already-dead tissue and is therefore a secondary player, not the primary cause, and it fades once new leaf growth resumes.

How to recognize heat tracking on your lawn

 
Heat tracking stripes—straw-colored lines matching mower tire width on a residential lawn

Heat tracking shows up as straight, tire-wide lines or narrow footpaths that follow your mowing pattern or common walking routes. Tug on a yellowed blade: if the root holds firm and looks white, you’re seeing heat tracking—chemical burns usually leave roots brown and brittle. A day or two of 85 °F+ weather after irrigation or rain is the classic trigger window.

If you’re unsure whether it’s heat tracking or something more serious, contact our lawn-care specialists for a quick confirmation.

Why heat tracking is not a chemical burn

Chemical phytotoxicity creates diffuse blotches or entire boom-width bands and harms crown tissue. Heat tracking, by contrast, produces razor-sharp lines that match tire spacing, leaves crowns intact, and resolves without reseeding once moisture returns. University trials confirm that properly applied fertilizers and herbicides cannot scorch turf at the labeled rates we use.

Best practices to prevent and recover from heat tracking

Deep watering: Irrigate ½–¾ inch every two to three days so moisture reaches 4–6 inches deep.
Higher mowing height: Maintain a 3½–4 inch cut to shade the soil, reduce leaf temperature, and speed regrowth.
Traffic timing: Avoid driving or heavy foot traffic on the lawn during mid-afternoon heat; mow in the morning when blades are cool and hydrated.
Patience: Cool-season grasses typically green up in three to six weeks once conditions improve. Fungicides are rarely needed—even if Ascochyta is present—because the pathogen is superficial.

FAQ: Do you need to reseed after heat tracking?

No. Because roots are unaffected, the plant produces new blades on its own. Reseeding is only necessary if large areas were already thin before the event.

Think your lawn is showing heat tracking? Let us help.

Our turf experts can confirm heat tracking, rule out other issues, and design a custom recovery plan. We serve Sioux Falls, SD, Sioux City, IA, and nearby communities in South Dakota, including Tea and Harrisburg. If you’re in the Sioux Falls area, call (605) 251-6880. For the Sioux City area, reach us at (712) 253-8024. We’ll put science to work for your lawn!