Rhizoctonia brown patch

Gail Ruhl, Senior Plant Disease Diagnostician, Purdue University

Rhizoctonia Brown Patch is a fungal disease with development favored by temperatures in the mid to upper 80's, high humidity, heavy dew formation and occasional precipitation.   This pathogen is a foliar disease which begins as irregular shaped lesions on the leaf blades.  This stage of the disease often goes unnoticed.  As the lesions on the individual blades increase and coalesce, a yellowish/brown cast begins to develop.  The fungus spreads to neighboring blades of grass via cottony-white mycelium. The symptoms are expressed as irregular patches, and may grow to several feet in diameter if favorable conditions for disease development persist for long periods of time.  Under Indiana conditions, infected turfgrass areas are seldom killed by this disease, but may exhibit considerable thinning. Once favorable growing conditions for the turfgrass return, lawn quality can be restored.  See Publication (BP-106 pdf file) for management suggestions.

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