Diagnosing Brown Rings in St. Augustine Lawn

A Caldwell, TX homeowner has a 6-foot brown ring in 6-month-old St. Augustine sod that expanded despite fungicide and chinch bug treatments.

Key Management Adjustments

• Stop winter fertilization — excess nitrogen feeds fungal pathogens
• Reduce irrigation frequency — water deeply in morning only, allowing drying during day
• Current schedule (2x/week, 15 min) likely keeps surface too wet

Fungicide Options for Brown Patch

If cultural changes don't halt expansion, these active ingredients target brown patch (Rhizoctonia solani): azoxystrobin, propiconazole, thiophanate-methyl, flutolanil, myclobutanil, and others. Scotts products contain one or more. Rotate chemistries to prevent resistance.

Natural Chinch Bug Control

Mycotrol-O (Beauveria bassiana strain) is a fungal biopesticide targeting chinch bug nymphs. Reintroduces beneficial fungus to soil. Expensive but effective in cooler, moist conditions.

Next Steps

Monitor the ring through winter. Cool temperatures naturally slow fungal activity. Resume cultural management in spring; treat only if expansion continues.