Yellow Patch (Cool-Weather Brown Patch) Fungicides

Yellow patch, also called cool-weather brown patch, is a Rhizoctonia disease of cool-season turf during prolonged cool, wet weather.

What to Look For

Yellow, tan, or reddish rings and patches range from several inches to a few feet across. Leaves may be blighted, but crowns and roots often survive and recover when conditions improve.

Why It Develops

Cool temperatures, cloudy wet weather, long leaf wetness, poor drainage, excess thatch, and low turf growth favor disease.

Reduce Disease Pressure

• Improve drainage and airflow.
• Reduce excessive thatch.
• Water early and avoid extending leaf wetness.
• Maintain balanced fall fertility without forcing lush growth.

What University Research and Extension Guidance Says

University guidance notes that damage is often cosmetic and recovery occurs as weather becomes warmer and drier. Preventive fungicides are most useful on high-value sites with a predictable history. Some university trials indicate that appropriate fall nitrogen may improve turf recovery rather than worsen this cool-weather disease.

Choosing and Using a Fungicide

Use the products below as a starting point, then match the active ingredient, FRAC group, turf species, use site, timing, rate, interval, and watering directions to the current product label. Preventive or very early applications are usually more reliable than rescue treatments after extensive injury. Rotate effective FRAC groups and combine fungicides with the cultural changes above.

Research and label note: University research may identify useful activity even when a current product label does not name this disease. That is research evidence, not a label direction. Apply a product only where the turf or application site and use pattern are permitted, and follow the complete label and applicable state requirements.

University sources: University of Kentucky: Chemical Control of Turfgrass Diseases 2024; NC State Extension: Yellow Patch in Turf.