Lawn Disease Prevention: Fall Recovery Plan

Fall Lawn Diseases: Act Before Winter

Fall cool, damp conditions create the perfect environment for fungal diseases. If left untreated, these diseases can devastate your lawn over winter and leave large dead patches in spring. Early identification and treatment in fall is far more effective than spring recovery.

Common Fall Lawn Diseases

Brown Patch

Appearance: Circular patches of brown, dead grass six inches to several feet in diameter. A dark smoke ring border may be visible in early morning dew.

Cause: Rhizoctonia solani fungus, active when nighttime temps are above 60 degrees and grass stays wet for 12 or more hours.

Treatment: Reduce evening watering. Apply fungicide containing azoxystrobin or propiconazole. Improve air circulation by trimming nearby shrubs.

Dollar Spot

Appearance: Small, straw-colored circular spots about the size of a silver dollar. Multiple spots may merge into larger dead areas.

Cause: Clarireedia jacksonii fungus, common in lawns low in nitrogen.

Treatment: Apply a light nitrogen fertilizer. Fungicide with chlorothalonil or myclobutanil for severe cases.

Leaf Spot and Melting Out

Appearance: Dark spots on individual grass blades that expand and kill the leaf, eventually reaching the crown and roots.

Cause: Bipolaris and Drechslera fungi, favored by cool, wet fall weather.

Treatment: Mow at the correct height, avoid overwatering, and apply a preventive fungicide if your lawn has a history of this disease.

Snow Mold Prevention

Snow mold develops under snow cover when the ground is not frozen. Two types exist: gray snow mold and pink snow mold. Prevention steps:

• Last mowing: Cut grass half an inch shorter than normal for the final mow
• Rake leaves: Remove all leaf litter before snow falls
• Avoid late nitrogen: Do not fertilize within six weeks of expected snowfall
• Aerate: Core aeration reduces thatch and improves drainage

Preventive Lawn Care Schedule

• September: Core aerate, overseed, apply fall fertilizer
• October: Apply preventive fungicide if disease history exists
• November: Final mow, clear all debris, prepare for snow mold prevention

A lawn that enters winter healthy and disease-free has a 90 percent better chance of a lush spring greenup. Prevention costs a fraction of the recovery effort.