A Record-Wet Summer Means Watching for Lawn Fungus

This summer didn't look like a typical Central Illinois dry spell. Peoria just logged its 2nd-wettest August in 132 years of record-keeping, and 2026 is running as the 8th-wettest year to date — nearly 9 inches above normal precipitation. With more rain moving through the area this week and the push toward our average October 15 first frost underway, a lot of area lawns are showing something homeowners don't expect out of a wet year: fungal disease.

Why a Wet Year Is Actually Harder on Turf Than a Dry One

Turfgrass fungal pathogens don't need drought stress to cause damage — they need the opposite: extended periods of leaf wetness, humid air sitting low in the canopy, and soil that stays saturated longer than roots can use. That's exactly what this year's pattern has produced across the Peoria area. Diseases like brown patch, red thread, and dollar spot all spread fastest when grass blades stay wet for six hours or more at a stretch, which has been the rule rather than the exception through a summer and early fall this wet.

What to Actually Look For

Brown patch shows up as roughly circular patches of tan or brown turf, often with a darker, smoke-colored ring visible around the edge in early morning dew. Red thread leaves pinkish-red, thread-like fungal growth on blade tips, usually in patches a few inches to a couple feet across. Dollar spot causes small, silver-dollar-sized bleached spots that can merge into larger irregular areas if left untreated. All three are easy to mistake for normal fall color change from a distance, but the defined patch shapes and the fungal threads or powder visible up close are the giveaway.

Mowing Wet Grass Is Making It Worse

With more rain in this week's forecast, it's worth resisting the urge to mow on schedule if the lawn is still wet — mower decks and tires physically carry fungal spores from an infected patch to clean turf across the rest of the yard, which is one of the most common ways a small disease spot turns into a lawn-wide problem. Letting grass dry out before mowing, and cleaning the mower deck between sections if disease is already visible, cuts down on spread more than almost anything else a homeowner can do for free.

The Bottom Line

The wettest summer in over a century doesn't mean a lawn is in the clear — it just means a different set of problems than drought, and fungal disease is the big one this year. Catching it now, before cool-season grass goes dormant for winter, gives treatment time to actually work instead of carrying disease pressure into next spring's green-up.