Brown Patches in Wet Clay Lawn: Drainage and Fungus

Pennsylvania lawn: Former evergreen site. Wet, mushy after rain. Brown patches, grass pulls up rootless. Suspects evergreen sap acidity. Needs pH test method.

Primary Issue: Drainage, Not Acidity

• Mushy 2+ days = anaerobic soil = root death
• Evergreen needles acidify, but drainage kills first
• Rootless pull-up = crown/root rot from saturation

Diagnostic Priority

1. Soil test: pH + texture (kit or lab). Target pH 6.5-7.0
2. Percolation test: Dig 12" hole, fill water. >24 hrs to drain = problem
3. Check for fungal lesions on grass blades

Fungus Likely (Brown Patch)

• Wet, warm + high N = Rhizoctonia
• Circular patches, "smoke ring" at edge
• Links: TAMU plant pathology, UNL brown patch

Drainage Fixes (Priority Order)

1. Core aerate + compost topdress: Annual, builds slowly
2. Sand amendment: 5-10% tilled in (NOT topdressed)
3. French drain: Perforated pipe to daylight/dry well
4. Regrade: Berms/swales to redirect water
5. Dry wells: Vertical PVC + gravel at low points
6. Rain garden: Native wet plants in low spot

Acidity Management

• If pH <6.0: Lime per soil test (not guess)
• Gypsum if high sodium
• Don't lime blindly—can worsen structure

Grass Upgrade

• If >12-15 yr old variety: Replace with disease-resistant hybrid
• Tall fescue blends handle wet better than bluegrass/rye

Immediate

• Stop fertilizing
• Reduce watering
• Fungicide if active disease (azoxystrobin)
• Plan fall drainage project

Fix the water, the pH often self-corrects. Wet soil = dead grass regardless of pH.