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Fixing Brown Patches in Lawns

Posted by Jack Warpinski June 17th, 2020. Updated July, 6th 2023

You’ve seen it before! Your lawn has been looking great all spring and you want is to keep it that way through summer so you water a few times a week to help mother nature out through the hot summer. Then, anywhere from early June to late August, strange brown patches appear that only seem to grow in size, even though you water more and more.

Water isn't the problem!

You most likely have a common lawn fungal disease! It is called ‘Brown Patch’ in Tall Fescue or Zoysiagrass and ‘Summer Patch’ in Kentucky Bluegrass. These fungi attack your lawn when the weather is hot and humid during the night. Generally, if the nighttime weather is above 70 degrees and humid for several nights in a row, you should be on the lookout for these diseases.


These fungal infections present themselves as small, irregular blobs or rings of dead grass that grow in size as time progresses.

Brown Patch in Lawn

To confirm the diagnosis, take a close look at the grass that is starting to turn yellow on the outside edge of the patches. You will see that the tip of the grass blade is turning brown and curling up while the base of the blade remains green.

Prevention and Control

Follow these practices to prevent brown patch from infecting your lawn, and to control it if it does. Luckily, most lawns will eventually recover from these diseases without replanting as long as the issue is dealt with in a timely manner.

  • Use recommended NTEP grass varieties.We only grow sod from the best performing seed varieties, which are selected for (amongst other things) their resistance to summer diseases.
  • Make sure your mower blades are sharp.Sharp mower blades will cleanly slice the grass when you cut your lawn. Dull blades will tear the blades, providing much greater surface area for the fungus to enter the plant.
  • Reduce fertilizer usage. Fertilizer should be avoided in the summer if you have a cool-season lawn. Increased nutrients will cause the grass to grow faster which actually weakens the cell walls in the plant, making it an easy target for fungal disease
  • Water heavily and infrequently in the morningsIf your lawn needs water, it is best to water in the morning, no later than 12 noon. This gives all afternoon for the grass to dry out. Fungus LOVES warm, moist nighttime conditions and watering in the evenings will almost guarantee a problem!
  • Fungicide. If you have very high expectations of your lawn and want to ensure it remains impeccable through the summer, you should apply a fungicide as a preventative every 3 - 4 weeks. The fungicide coats the blades of grass and prevents infection in the first place. Fungicide can also be used to treat a fungus problem that has already appeared.


If your cool season lawn was severely damaged by fungus during the summer, you can easily overseed in September once the cooler weather returns. Be sure to use an NTEP Selected Blend to help fight fungus next year!