Melting Out Fungicides

Melting out is the crown- and root-decline phase of a leaf spot disease complex. It is especially damaging to susceptible Kentucky bluegrass when early leaf infection progresses into the lower plant.

What to Look For

Turf thins in irregular yellow, reddish-brown, or straw-colored areas. Lower stems, crowns, and roots darken and die, and affected plants pull apart easily. Earlier leaf spots may still be visible on surviving blades.

Why It Develops

Leaf infection often begins during cool, wet weather; crown and root loss becomes more visible as temperatures rise and turf is stressed. Shade, thatch, low mowing, poor airflow, unbalanced fertility, and drought increase severity.

Reduce Disease Pressure

• Overseed with resistant cultivars where the disease is chronic.
• Maintain balanced fertility and avoid abrupt flushes of growth.
• Raise mowing height where practical and manage thatch.
• Water early, improve airflow, and prevent severe drought stress.

What University Research and Extension Guidance Says

NC State emphasizes intervention during the early leaf-spot phase because fungicides may slow additional spread after melting out begins but cannot restore dead crowns. University efficacy ratings should guide product choice because performance varies substantially among chemistries.

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: NC State Extension: Leaf Spot in Turf; University of Kentucky: Chemical Control of Turfgrass Diseases 2024.