Copper Spot Fungicides

Copper spot is an occasional disease of creeping bentgrass and annual bluegrass, most often on closely mown, low-fertility turf during warm, humid weather.

What to Look For

Small copper, salmon, or reddish-brown spots appear suddenly and may merge into irregular blighted areas. Individual leaves can show water-soaked lesions before turning copper colored.

Why It Develops

High humidity, prolonged leaf wetness, warm weather, and low nitrogen favor outbreaks, particularly on stressed putting turf.

Reduce Disease Pressure

• Use light, balanced nitrogen where deficiency is contributing to poor recovery.
• Water early and improve airflow to shorten leaf wetness.
• Avoid unnecessary mowing or traffic stress during active disease.
• Confirm the diagnosis because copper spot can resemble dollar spot or other foliar blights.

What University Research and Extension Guidance Says

Published efficacy data are limited. Kentucky reports good control in trials from several fungicide groups and combination products, while classifying other options as limited-data rather than ineffective. That makes early treatment, diagnosis, and close observation especially important.

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.