Red Thread

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What is Red Thread? Laetisaria fusiformis

  • A troublesome disease that infects lawns across the country
  • Red Thread is a foliar disease that usually occurs during mild temperatures and long periods of wet turf.  The disease is more prevalent in spring and fall but can occur in any season.
  • As a foliar disease Red Thread will not damage the Crown and Root structure.  As weather conditions and fertility improves the lawn will improve.
  • Malnourished turf is often a leading cause of Red Thread.  Deficient nitrogen and/or phosphorous levels can result in serious outbreaks.
  • The disease spreads throughout the lawn in the form of spores. These spores are spread by wind, air, water and humans. The disease may be caused by improper mowing and watering (refer to Weed Man Mowing and Watering Fact Sheets for proper maintenance procedures). Discuss maintenance practices with your Columbus North, OH Weed Man.
  • Red Thread attacks most types of grass but is generally found on lawns that contain high proportions of the Fescue species.
  • Under ideal conditions the fungi appear as small red filaments that may be seen projecting out of the affected leaves.
  • Other factors that may encourage the spread of the disease are poor air circulation, poor drainage and a thatch layer greater than ½ “.


  • Controlling Red Thread can be achieved through modifying the lawn environment. The thinning of trees will improve air circulation and the penetration of sunlight. 
  • Core aeration will reduce the thatch layer and improve water penetration. Regular applications of a balanced fertilizer will produce a healthy lawn, which is more resistant to attacks by this disease. 
  • Have your Columbus North, OH Weed Man fertilize your lawn and advise you on correct maintenance to ensure a healthy disease free lawn.
  • If Red Thread continues to be an ongoing issue year to year, fungicide applications might be considered.  Please contact your Columbus North OH Weed Man for recommendations and pricing.‚Äč
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