Brown Patch, also known as Rhizoctonia solani or Rhizoctonia Blight, attacks lawn grass during the early summer. It causes small (silver dollar sized) spots of tan/brown on most lawn types. These spots can eventually merge to infect large areas. Large brown-patch thrives best during hot, humid nights. It makes its appearance in circular, smoky-looking spots six to eight inches in diameter. The grass in these spots have at first a cooked appearance as if scalded with hot water. A close examination reveals a fine cobwebby growth on the outer margins of the spots.
Given a few hours of hot sunshine, the spots turn brown, hence the name “brown-patch.” If no remedy is applied and the weather is favorable, some of these spots may spread in the course of a few nights over an entire green.
Do not apply nitrogen fertilizer to grass prior to or during hot and humid weather. The removal of dew, by dragging a water hose across the area each morning has proven effective as an aid in reducing brown patch. Any necessary watering should be done in time for the grass to dry prior to nightfall.