Is That Spot in My Yard Some Sort of Lawn Fungus?

By TruGreen November 8, 2016
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Discover the lawn diseases that can affect your lawn each season.

<p>Does my lawn have some sort of fungus</p>

Lawn disease and fungus can invade anyone’s lawn. Most fungi will show signs and symptoms, but there is always a chance that something could be going on that you can’t see. The best thing to do is educate yourself on the common signs and symptoms of various lawn diseases and contact a lawn care expert as soon as you suspect something is wrong. 

There are many types of lawn fungus that can pose a threat to your lawn. Cool or warm temperatures, over- or under-fertilization, unbalanced fertilization and certain watering habits all can contribute to the onset of a lawn fungus or lawn disease. 

There are a number of signs that a lawn fungus of some sort is affecting the health of your lawn. Here are some of the most common.

Common Signs of Lawn Fungus Diseases

  • Spots/patches
  • Bleached turf
  • Stunted growth
  • Shredded or shriveled grass blades
  • Lesions on leaf
  • Dark growth at the base of the plant

For the lucky (or unlucky depending on your opinion of snow) grass growers in the north, some diseases appear in certain seasons. Check out our guide below on which diseases appear in each season.

From fall to early spring:

  • Pink snow mold: Begins as light yellow-green areas, infected turf becomes bleached, grass begins to feel slimy, white to pink fungal growth may become visible with affected areas showing a pinkish border. Favors conditions with abundant moisture and temperatures 32° to 55° Fahrenheit.
  • Gray snow mold: As with the pink snow mold, this fungus starts as light yellow-green areas, infected turf becomes bleached and matted. White to gray fungal threads may be visible, with hard, reddish-brown seed-like structures present in leaves and crowns. Favors conditions with abundant moisture and temperatures 30° to 40° Fahrenheit.
  • Yellow patch: Circular patches or rings of light tan to yellow patches (depending on grass type), reddening of leaf blades from tip. Favors cool, wet conditions and recent sod is often more severely affected.
  • Leptosphaeria patch: Begins as circular yellow patches. In advanced states grass turns tan or brown, crowns turn black. Favors cool, wet conditions.

From spring to early summer:

  • Stripe smut: May stunt lawn growth, grass turns a lighter, yellow-green color, veins turn black and rupture, blades shred, shrivel, and curl. Favors conditions with high moisture and temperatures 50° to 60° Fahrenheit.
  • Red thread/pink patch: First appears as small patches of water-soaked plants, patches become bleached to light pink or red. Favors cooler weather and moist conditions. Learn more about red thread here.
  • Helminthosporium leaf spot/melting out: Begins showing as tiny, circular dark spots, spots then enlarge and turn purplish, eventually centers of spots can become light brown. Crown rot causes thinning of turf. Favors cool, overcast, moist conditions and improper mowing.

From summer to early fall:

  • Dollar spot: Displays circular patches (about 1 to 6 inches in size) of bleached turf, light tan leaf lesions with reddish-brown borders, white fungal growth may be visible in early mornings. Favors humid conditions and temperatures of 60° to 80° Fahrenheit. Learn more about dollar spot lawn disease here.
  • Fusarium blight: Begins as dark, circular patches that appear drought-stressed, later patches turn to light straw color, crowns usually die. Favors humid conditions, stressed turfgrass, daytime temperatures of 80° to 95° Fahrenheit and night temperatures above 70° Fahrenheit.
  • Pythium blight (grease spot or cottony blight): Starts as small, blighted spots, leaves show as greasy and dark at first but fade to a light brown color, spots merge forming large, irregular patches.
  • Rhizoctonia blight (brown patch): Circular patches (about ½ to 2 feet in diameter) of light brown turf, light brown lesions with dark borders occur on leaf blades, dark fungal growth at the base of grass. Favors moist conditions and temperatures of 75° to 85° Fahrenheit.  Read more about brown patch lawn disease here. Favors high humidity, poor air circulation, and temperatures of 85° to 95° Fahrenheit.
  • Nematodes: Displays discolored, yellowed turf, stunted grass growth, thinning. Favors moist soil, light-textured soil and temperatures of 60° to 85° Fahrenheit.
  • Fairy ring: First appears as circular patches on dark green, fast-growing grass, patches enlarge into rings, ring of dead grass may occur on inside of green grass. Favors mild temperatures and moisture, but turf browning may occur during hot, dry conditions.

Late summer to fall:

  • Powdery mildew: White to gray powdery growth appears on leaf surfaces, later leaves may turn yellow, thinning may occur. Favors high humidity, low light intensity, and temperatures around 65° Fahrenheit.
  • Rust: First appears as small, yellow flakes on leaves, flecks enlarge to form rust-colored pustules, overall turf color may be yellow-orange to reddish-brown. Favors stressed turf and moderately warm and humid conditions.
  • Yellow tuft: Display as yellow spots (½ to 4 inches in diameter), spots consist of a dense cluster of yellow shoots, tufts may easily detach. Favors cool and wet conditions.

Beware that damage in a lawn isn’t always caused by a fungus, so it’s unwise to turn to a lawn fungus treatment without more knowledge of the problem. Once the issue is determined, you can then identify the safest and most cost-effective lawn disease treatment or lawn care plan designed to restore the lawn to lush, green health. 

Your local TruGreen® experts are trained to determine what is ailing your lawn and if lawn fungus treatment is really what you need. They can provide valuable advice on how to treat lawn fungus as well as tips for proper mowing and watering. In addition, the ongoing technical support they offer can greatly reduce the likelihood of lawn damaging diseases reappearing in your lawn and will fortify your lawn fungus control. Visit or call 866.688.6722 today for more information.

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