Rhizoctonia solani
Brown Patch (Rhizoctonia solani) is a serious fungal disease affecting Tall Fescue, Perennial Ryegrass, Kentucky Bluegrass, St. Augustine Grass. It triggers under nighttime temperatures >68°f with prolonged foliar moisture and high relative humidity (>85%). Symptom manifestation begins with leaves exhibit water-soaked dark lesions that dry into irregular tan spots with dark brown margins. turf crowns remain green. Curative control requires Azoxystrobin (Heritage G) or Propiconazole (Banner MAXX) applied at 14–21 day intervals during hot, humid spells.
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Curative treatment of Brown Patch requires strict adherence to statutory EPA product label directions. University extension trials demonstrate high efficacy with the following commercial chemistries:
Broad-spectrum systemic strobilurin (Azoxystrobin, FRAC 11) for curative and preventative control of turf fungi.
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Check Price on Amazon →Pathogen virulence operates strictly under the classic Plant Disease Triangle: infection requires an active pathogen inoculum, a genetically susceptible turfgrass host, and conducive microclimatic conditions (primarily prolonged leaf canopy moisture exceeding 10 consecutive hours combined with elevated rootzone humidity). Unmown or excessively dense turf stands impede airflow, creating an insulated stagnant microclimate where fungal spore germination accelerates.
When evaluating suspect turf patches, cross-examine rootzone integrity against foliar discoloration. True root-rot pathogens compromise subterranean anchoring, allowing turfgrass mats to be pulled up effortlessly with zero tensile resistance. In contrast, foliar blights damage leaf blades while leaving crown tissue and primary adventitious roots viable for regenerative recovery once fungicide active ingredients are introduced.
Cultural Protocol: Avoid evening irrigation; water only between 4:00 AM and 8:00 AM. Reduce synthetic nitrogen fertilization during July and August. Always avoid excess evening irrigation; irrigate early between 4:00 AM and 8:00 AM to allow rapid sun-drying of turf foliage. Keep cutting blades sharp to minimize ragged blade wounds through which fungal hyphae penetrate.
Chemical Protocol: Azoxystrobin (Heritage G) or Propiconazole (Banner MAXX) applied at 14–21 day intervals during hot, humid spells. Rotate active ingredients across different FRAC / IRAC mode-of-action groups (such as rotating Group 11 strobilurins with Group 3 triazoles) to prevent resistant fungal strains from dominating your lawn ecosystem.
Brown Patch is recognized by Tan to brownish-yellow with a dark purplish "smoke ring" border in early morning hours. forming 6 inches to 3 feet circular patches.. Blade symptoms: Leaves exhibit water-soaked dark lesions that dry into irregular tan spots with dark brown margins. Turf crowns remain green.
Primary susceptible hosts include Tall Fescue, Perennial Ryegrass, Kentucky Bluegrass, St. Augustine Grass. Maintaining proper fertilization and irrigation reduces pathogen virulence.
Extension-recommended treatment: Azoxystrobin (Heritage G) or Propiconazole (Banner MAXX) applied at 14–21 day intervals during hot, humid spells. Active ingredient: Azoxystrobin (QoI / Group 11 Fungicide) & Propiconazole (DMI / Group 3 Fungicide).
Avoid evening irrigation; water only between 4:00 AM and 8:00 AM. Reduce synthetic nitrogen fertilization during July and August.
