Brown patch tends to be most severe in lawns fertilized heavily with nitrogen fertilizer earlier in the season. Grass in these lawns tends to be lush and remain green longer into the season. These conditions makes turf grass more vulnerable to attack by the brown spot fungus. This disease is characterized by the development of irregular, circular areas. Grass in affected areas loses its normal green appearance and develops a straw-brown color.
Affected areas range in size from a few inches to several feet in diameter.
Generally, brown patch attacks only the leaves and stems of the grass. However, if not controlled it can attack the roots and kill large areas of the lawn. Homeowners who've spotted brown patch in their St. Augustine, zoysia, or centipede lawns may want to apply a fungicide to slow disease development and increase chances of stronger turf as we approach the winter season. Preferred fungicides for brown patch control include Spectracide Immunex, Terraclor or Bayleton. Fungicides such as Daconil 2787, or similar products with chlorothalonil as the active ingredient, will slow down the spread of brown patch but are not as effective as Immunex or Terraclor.