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Brown Patch Disease – There is fungus among us

What is brown patch?
It’s a warm humid night and you’re looking at your beautiful lawn while enjoying the evening. You wake up the next morning and notice some yellow patches developing… You wake up the next morning and the yellow patches begin to turn brown.  What’s going on? Overnight yellowing can be a symptom of a number of different lawn diseases. This particular culprit is most likely a lawn fungus called brown patch. Dennis Patton (Master Gardener for Kansas State) says, “You can come home at 5 in the afternoon, walk through a perfectly green front lawn and wake up to brown patch taking hold.” That’s because the foliar disease started coloring your grass blades with brown leaf spots while you were sleeping. 

How and when does it thrive?
Brown patch thrives when it is hot and humid, and can affect your lawn in late spring, summer or early fall, depending on what type of cool-season grass you have, where you live and recent weather conditions. It also survives the winter (dormant) in the lawn’s thatch. Brown Patch survival also depends on what type of cool-season grass you have, where you live, and recent weather conditions. Prolonged wetness from rain, dew, evening or nighttime watering, or poor drainage; or any other activity that keeps grass blades wet can create ideal conditions for the growth of fungal disease. Temperature also plays a part in ideal living conditions for a lawn disease/fungus. When temperatures are above 80°F during the day and 65°F at night the lawn remains moist, it is likely that a disease / fungus will pop up.  In addition, if the grass that has been over-stimulated with nitrogen just before or during hot, humid weather, the grass tends to be more susceptible to brown patch.

How to identify brown patch

  • Big brown circles – These circular patches are the disease spreading from grass blade to grass blade. They turn brown and brittle and create the spots that give the brown patch its name.
  • Lesions – In most cases, the entire blade of grass won’t be brown. Instead, there will be an abundance of copper and brown lesions.
  • Green center – Often, the center of the circle will recover, creating a pattern that kind of looks like a donut.
  • Smoke ring – The perimeter is a gray-white band called a “smoke ring.”
  • White mycelium – In the morning on dew-covered turf, white mycelium can often be seen between and on grass leaves of the affected areas. White mycelium appears thin, white, and spider-web-like.
  • Rotted sheathes – tug on the green grass, if it separates easily, this is a tell-tale sign of brown patch.

These signs should help you identify if your lawn is suffering or succumbed to the fungus. However, It’s important to keep in mind that, like most diseases, you may not see all the symptoms. 


This is an early stage of Brown Patch Disease
This is an early stage of Brown Patch Disease
This is an advanced stage of Brown Patch Disease
This is an advanced stage of Brown Patch disease
This is an image of brown patch lesions on a blade of grass
Lesions on a blade of grass caused by Brown Patch

When does it happen?

  • Cool – season grasses like perennial ryegrass, tall fescue, Kentucky bluegrass, and bentgrass usually start showing symptoms in late spring. 
  • Warm – season species like Zoysiagrass, St. Augustinegrass, centipedegrass, and  Bermudagrass show symptoms twice during the year: early spring and late fall.

Control Measures

  • Aeration – Increasing air circulation in your lawn can sometimes dry out and cure your brown patch problem. If anything, it often causes the fungus to return to its dormant state.
  • Dethatch – Like aerating, dethatching will increase air movement and dry out the fungus, leading to  elimination altogether or dormancy.
  • Change your lawn care practices – Brown patch thrives in wet, warm, fertile lawns. Reduce your watering, avoid excessive nitrogen fertilizer in high growth times and avoid watering in the evenings; which increases the risk of fungal growth.
  • Don’t mow – Mowing a diseased lawn is a hard NO. Like coughing without covering your mouth, you’ll fling the disease everywhere, increasing the risk of infection in remaining healthy areas.
  • Increase drainage – Improper drainage increases moisture, making brown patch thrive. With good drainage, diseased lawns will dry out easier, reducing and even eliminating the problem.
  • Fungicide – Fungicide treatments are available to treat, maintain, and get rid of lawn disease. 
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