Brown patch lawn disease is one of the most destructive of all turf lawn diseases. It sneaks up on you and destroys large areas of turf virtually overnight when the weather conditions are just right. Brown patch lawn disease isn't picky; it attacks a wide variety of grass types, and really likes the lawns receiving large amounts of fast release nitrogen fertilizer. Learn more about how lawn disease develops and tips to prevent it.

Brown Patch Loves Hot Summer

“Brown Patch is the most damaging turf grass disease”

Brown patch is really a summer lawn disease that's caused by a fungus called Rhizoctonia. The disease begins to show growth when temperatures reach 65°, but the most active growth of brown patch lawn disease occurs at temperatures of 80-85° when humidity levels are very high. The fungi survive the winter in plant debris (thatch) and enter the leaf tissue through wounds caused by mowing and through the pores (or stomata) when daytime temperatures get into the 70s. Infected turf grass can go quite a while without showing damage because it’s actively growing. But, if the daytime temperatures reach the mid 80s and nighttime air temperatures stay above 70°, the grass will be under stress. Then, lawn disease damage can become visible almost immediately. Once started, brown patch lawn disease spreads fast. Brown patch damage first appears as circular areas of brown and dead grass surrounded by a narrow, dark ring. This dark, smoke ring is not always visible, but is more likely to appear in the early morning when there's dew on the grass. Brown patch lawn disease grows out from a central point, so these circular areas can enlarge rapidly. Brown patch circles range from a few inches in diameter to several feet, and are not always true circles. Sometimes the patches grow together, creating large irregular dead areas. Diseased turf first appears water soaked with leaf edges showing a wavy or wilted pattern, but soon dies completely and mats down, creating a sunken effect.


Cultural Management: Preventing Brown Patch Lawn Disease

Since high levels of fast release nitrogen increase disease activity, Spring-Green uses a correct blend of fertilizers for lawn fertilizing during the warmer months. Mow less frequently during periods of hot and humid weather, this reduces stress and limits the movement of grass disease by being carried on your feet or mower. If possible, increase light and air penetration, or movement, by pruning overhanging trees and shrubs. During cooler seasons, open up the thatch layer with power core aeration. If these cultural cures fail, a preventative fungicide lawn treatment program may have to be applied to control this most damaging of lawn diseases. [attached-images title="What Brown Patch Looks Like"]


  • Brown patch is the most damaging of all turf grass diseases
  • Brown patch lawn disease becomes most active when day temperatures are over 85° and night air stays above 70°
  • Because infected plants may appear healthy, brown patch damage can occur very fast when conditions are right
  • Avoid high levels of nitrogen in fast release form; it encourages brown patch development

Learn more about grass facts and keeping your lawn healthy and green. At Spring Green, we take brown patch lawn disease seriously because we know the damage it can cause. If you ever suspect this disease of infecting your turf, please contact your neighborhood Spring Green lawn service. 

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