Are Those Brown Spots In Your Lawn Fungus?

Spring’s heavy rainfall can turn a healthy lawn into a prime target for lawn fungus outbreaks. If you’re seeing odd brown patches, bleached circles, or pinkish strands in your turf, you’re likely dealing with one of three common diseases: brown patch, dollar spot, or red thread. In this guide, we’ll explain how to identify each fungus, share proven fungicide treatment tips, and outline simple cultural practices to keep your grass green and disease-free all season.

What Causes Lawn Fungus in a Rainy Spring?

• Prolonged leaf wetness: Fungal spores germinate when grass blades stay wet for 8–12 hours.

• Warm days and cool nights: These classic spring conditions accelerate fungus growth.

• Compacted soil and poor airflow: Saturated turf holds moisture at the crown, creating a breeding ground for disease.

1. Brown Patch Identification & Treatment

Brown patch appears as irregular tan or dark-brown blotches, often bordered by a faint “smoke ring.” It thrives in temperatures between 65–85°F under humid, rainy conditions.

• Fungicide application: Choose a broad-spectrum product labeled for brown patch and apply every 10–14 days until symptoms disappear.

• Mowing height: Raise your blades to 3–3.5 inches to shade soil and slow disease spread.

• Watering schedule: Water deeply in the early morning only, allowing grass to dry by afternoon.

• Aeration: Improve soil drainage and airflow by aerating compacted areas.

2. Dollar Spot Control & Prevention

Dollar spot shows up as silver-dollar-sized bleached circles, sometimes with fine cobweb-like mycelium on dewy mornings. Low-nitrogen turf and extended leaf wetness make lawns more susceptible.

• Fungicide program: Schedule 2–3 treatments of a fungicide labeled for dollar spot, spaced 10–14 days apart.

• Nitrogen management: Maintain balanced soil fertility; avoid low-nitrogen conditions that encourage outbreaks.

• Thatch reduction: Dethatch or aerate to reduce thatch buildup and improve spray penetration.

3. Red Thread Identification & Treatment

Red thread manifests as bright pink or red filaments clinging to grass blades, turning patches a reddish or straw color. It commonly appears in cool, wet springs when turf is under light stress.

• Balanced fertilization: Apply a balanced fertilizer to help grass recover and outgrow fungal growth.

• Water management: Irrigate deeply but infrequently, early in the morning to prevent overnight moisture.

• Improved drainage: Aerate regularly and trim back low branches to boost air circulation.

Long-Term Lawn Fungus Prevention

1. Adjust mowing height: Keep grass blades at 3–3.5 inches to crowd out spores and shade the soil.

2. Water wisely: Deep, early-morning watering only—avoid evening or overnight irrigation.

3. Soil health: Test pH (ideal 6.2–7.0) and lime if necessary to create less hospitable conditions for fungus.

4. Regular aeration: Relieve compaction in high-traffic or shaded areas to speed surface drying.

5. Seasonal monitoring: Inspect your lawn weekly during wet spells and treat early at the first sign of disease.

Don’t let lawn fungus ruin your spring turf. With timely fungicide treatments and simple cultural practices, you can keep your grass thick, green, and disease-free all season long. Ready for professional fungal inspection or fungicide application?