Diagnosing a Dead Grass Rectangle: Abiotic vs. Biotic

Straight Lines = Abiotic Cause

An 8x1 ft dead strip along a sidewalk with sharp edges suggests non-living factors:

• Chemical spill (herbicide, gasoline, cleaner).
• Physical blockage (plywood, tarp, equipment left during tree work).
• Sprinkler malfunction (sharp edge = head not rotating).
• Hot exhaust from parked machinery.
• Salt/ice melt runoff from sidewalk.

Curved Edges = Biotic Suspect

If edges are irregular, consider:

• Chinch bugs (St. Augustine) – soap flush to confirm.
• Fungal patch – look for smoke ring, lesion patterns.
• Grub damage – turf lifts like carpet.

Next Steps

1. Soap flush (2 oz soap/2 gal water over 2 sq ft) to rule out insects.
2. Check sprinkler coverage with catch cups.
3. Ask tree crew about equipment parking.
4. If abiotic: remove dead sod, loosen soil, reseed/sod.