Recurring Brown Spots in Louisiana Heat: Could Grubs Be the Culprit?

Annual brown spots appearing in September-October after damp weather, in the same locations each year, suggest a cyclical pest rather than a simple fungal issue. In Louisiana's hot, humid climate, grubs are a prime suspect.

Why Grubs Fit the Pattern

Grubs migrate upward in response to moisture and seasonal cycles, feeding on roots. Damaged turf lifts like a carpet because roots are severed. You may need to dig deeply — a post-hole shovel works — to find them, as they often stay below the surface.

Confirm Before Treating

Cut and peel back a 1-foot square of affected turf. Check the root zone for white, C-shaped larvae. Count them: 5-10 per square foot warrants treatment. Time insecticide applications for when grubs are small and near the surface (typically late summer/early fall).

Break the Cycle

Combine curative treatment with preventive practices: avoid overwatering in late summer, maintain proper mowing height, and consider a preventive grub control application next June-July if history repeats.