How to Treat Grass Fungus

Updated February 21, 2017

Fungal diseases in lawns can be a nuisance for homeowners and gardeners. Various types of grass fungi exist, including powdery mildew, rust infection, red thread, slime moulds and even pythium blight. Yellow, orange or red patches of fungi often can be seen in the grass. These types of fungi steal nutrients and moisture the grass needs. Getting rid of and preventing fungus will help you to maintain a healthy lawn.

Identify the type of lawn fungus you are dealing with to determine how best to treat the lawn.

Apply a fungicide to the area of fungus on your grass, per manufacturer's directions. Alternatively, make your own natural product by mixing 1 quart of water per 1 tsp baking powder. Pour it evenly over the infected area. The baking powder will help neutralise the fungus. Another natural solution is to cover the area with corn meal, which stimulates beneficial microorganisms that feed on pathogens.

Apply a nitrogen fertiliser to the lawn, particularly if it has fairy rings, red thread, rust or dollar spot. Follow the manufacturer's instructions. Several lighter applications are less likely to trigger disease than a single heavy application of fertiliser.

Cut the grass to length of about 3 inches, which is low enough to allow air to circulate around the grass. Water your grass in the morning to give the lawn time to dry from the sun during the day. Water only when the sun is expected to shine. Water at least to root level and only after the lawn had dried from the previous watering.

Rake up thatch, which is a layer of living and dead roots and shoots that form between the soil surface and green grass. Fungi feed on dead organic matter created from thatch.

Remove snow that will not melt, as most lawn fungi form after winter or during the fall. Removing lingering snow will help to keep the grass dry and prevent fungi. To prevent snow mould, continue mowing at the end of the summer season, and apply a fall fertiliser more than six weeks before the grass becomes dormant.


In some cases slime mould fungus can be removed by hosing it off with a forceful stream of water.

Things You'll Need

  • Fungicide
  • Baking powder
  • Corn meal
  • Nitrogen fertiliser
  • Lawnmower
  • Sprinkler
  • Garden rake
  • Fall fertiliser
  • Garden hose
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About the Author

YaShekia King, of Indianapolis, began writing professionally in 2003. Her work has appeared in several publications including the "South Bend Tribune" and "Clouds Across the Stars," an international book. She also is a licensed Realtor and clinical certified dental assistant. King holds a bachelor's degree in journalism from Ball State University.