Check Your Lawn For These 8 Most Dangerous Lawn Diseases!

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Spot what Lawn Disease Looks Like


A lawn disease is the result of a fungal infection taking over your grass. Under certain conditions, various types of invasive fungi can thrive and multiply in your lawn, where they will destroy your turf! This damage is characterized by dead, thinning, and discolored patches of grass, and the following situations could lead to an infection:

  • Hot days with cool nights
  • High humidity
  • Poor drainage
  • Watering your lawn at dusk
  • Diseased leaves in your yard

Holmes Lawn & Pest knows what to look out for when determining whether your lawn has a disease, and we wanted to pass that knowledge on to you. Services like aeration and fertilization can improve soil and grass quality, but symptoms of infection may still linger. The information below will help you spot some of the most common lawn diseases in Utah.

1) Brown Patch

identifying Brown Patch Disease

This disease is responsible for many unsightly patches appearing all over lawns in Utah. Brown patch causes roughly circular patches of yellow-to-brown grass to form over infected areas of a lawn. These patches can expand to about 3 feet in diameter, with irregular edges that resemble smoke rings around each infected patch. Infected grass within the patch will start to wilt and lose its green color, and the middle of the patch often appears sunken into the soil. Brown patch only affects cool-season turfgrasses; when the brown patch fungus infects warm-season grass types, the disease is called “large patch.”  

2) Necrotic Ring

identifying more summer patch

Necrotic ring is one of the most dangerous lawn diseases in Utah, and it is not hard to identify when you see it. Patches of grass that are infected by this disease start around 6 inches in diameter, and they often grow much larger and merge together. Necrotic ring is well known for the “frog eye” patches of grass, which feature a center of healthy grass surrounded by a ring of dead grass. Necrotic ring attacks the crowns and roots of turfgrass, which makes recovery from infection very difficult.

3) Snow Mold

identifying snow mold

Pink snow mold and gray snow mold are two similar diseases that creep into lawns over winter, and lawns start showing signs of damage as soon as snow melts in spring. Both types of snow mold cause spots of damaged grass to grow up to a foot in length, and the damaged grass typically appears matted and stiff. A pink cobweb-like growth can often be seen around the perimeter of pink mold, and gray mold spots sometimes develop hardened sclerotia in the center. Pink snow mold can withstand winter better than gray snow mold, but gray snow mold handles heat and drought stress better than pink.

4) Dollar Spot

Dollar Spot Lawn Disease

Though dollar spot is most active in hot, humid climates, this disease is common in Utah during the summer months. Dollar spot is a patch-type disease, but the patches it leaves in its wake are significantly smaller than most other diseases. As the name suggests, dollar spot patches are roughly the size of a silver dollar, but they tend to expand and merge together to form larger patches. This disease first starts by forming small spots of discoloration on individual grass blades, and those spots get bigger and spread to other grass blades to form the dollar spot patches.

5) Leaf Spot

identifying leaf spot

Infected leaves falling onto your lawn is likely the cause of leaf spot on your grass. Leaf spot is characterized by small dark spots forming all over an infected leaf/grass blade. These spots are typically an oval shape, they have brown centers, and the edges of the spots are a darker purplish color. Leaf spot spreads very quickly to healthy plant matter, which is why leaves should be removed from lawns promptly. Infected lawns will experience thinning and weakening of grass blades, and other issues may arise as a result, such as weeds and pests.

6) Red Thread

identifying Red Thread

The signs of red thread truly do resemble thick red threads weaved throughout a lawn. The reddish color is caused by red fungal spores on the threads that are known to come off on shoes and tools. If left untreated, these threads will begin to mat together, causing unpleasant tangles of diseased turf to form all across your yard. The damaged patches will appear dried out and hard, and the tangled nature of this disease makes it a nightmare to combat once it begins spreading.

7) Rust

identifying Rust Lawn Disease

The fungal disease known as rust creates flakes of yellow and orange that closely resemble common rust you would find on metal objects. Infected grass starts thinning out before it develops yellow specks, and those specks eventually turn into raised pustules that look like rust. As the pustules burst, the powder-like spores of the fungi are released and spread throughout a lawn. The powdery, orange spores are known to stick to shoes and lawn mowers, which are two of the main ways this disease spreads. You will likely notice an orange substance smeared on your shoes if your lawn is infected with rust.

8) Powdery Mildew

identifying powdery mildew

Similar to rust, powdery mildew covers grass in fungal spores that resemble a white powder. This disease most often affects garden plants, but infected plants in the garden can quickly lead to an infected lawn. Infected plants become covered in tiny white circles that quickly spread to form a “dusting” effect. Powdery mildew does spread easily and quickly, but it is one of the easier diseases to contain if the infection has not spread too quickly. You can apply everyday items like lime or baking soda to treat powdery mildew, or you can just call in the pros!

We hope you enjoyed this blog post, mowing your lawn is an important part of any lawn care routine so be sure to check out our blog to learn how often you should mow your lawn.

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