Lawn Grass Disease: 11 Most Common

Diagnosing the correct lawn grass disease can stump even experienced landscapers. It can be fungal, bacterial, or viral. The most common are usually caused by soil dwelling fungi.

Here is what may be destroying your lawn...

1. Anthracnose

  • Reddish brown spots with yellow markings.
  • Affected areas range from 2 inches to 20 feet in diameter.
  • Most common in wet weather.
  • Likely to hit grasses stressed by drought or low fertility.
  • Solution – Treat with fungicide.

2. Brown Patch

  • Dead plants within a circular area. Can be several inches to several feet in diameter.
  • Widespread on Bentgrass and warm season grasses.
  • Common in hot weather.
  • Solution – Remove thatch, aerate, and sprinkle on compost. Avoid fertilizers before warm periods. Treat with fungicide.

3. Crown Rot

  • Wet rot on the crown of the plant.
  • Solution – Treat with fungicide.

4. Dollarspot

  • Dead grass in small circles on cool weather grasses. Larger circles on warm-season grasses.
  • Straw colored bands with reddish brown border on leaves.
  • Most common in spring and fall. Can appear throughout lawn.
  • Solution – Use fertilizer high in nitrogen, aerate the lawn, and sprinkle compost over it. Treat with fungicide.

5. Fusarium Blight

  • Reddish brown grass in irregular patches of wilted turf.
  • Circular diseased area (1 to 8 inches in diameter).
  • Only in full sun, showing green center.
  • Solution – Difficult to control. Aerate and remove thatch. Mow high during the summer.

6. Leaf Spot

  • Reddish brown to blue-black circles on leaves.
  • Irregular shaped disease area.
  • Common in Bluegrass.
  • Solution – Mow high and add compost. Reduce use of high nitrogen fertilizer. Treat with fungicide.

7. Melting Out

  • Leaves that wither, turn brown and die.
  • Most common when termperatures and humidity are high.
  • Solution – Treat with fungicide. Reseed with resistant variety.

8. Powdery Mildew

  • Powdery white dust on the blades.
  • Common in shady areas with poor air circulation.
  • Solution – Treat with fungicide.

9. Pythium Blight

  • Wilted, greasy-looking turf. Tan and shriveled or dead grass.
  • Circular diseased area (1 to 8 inches in diameter). In low areas. Can be in streaks.
  • Most common when weather is warm and wet. Common on cool-season grasses.
  • Solution – Use less nitrogen fertilizer. Don’t fertilize at all in hot weather. Remove thatch and aerate.

10. Rust

  • Red, orange or brown powder on the blades.
  • Thin turf.
  • Common in shady, damp areas.
  • Solution – Water only in early morning so grass can dry quickly. Mow frequently at recommended heights.

11. Snow Mold

  • Pink or gray mold covering the turf after the snow melts in the spring.
  • Circular diseased area.
  • Solution – Mow lawn in fall. Avoid early fall fertilizing. Treat with fungicide.

Controlling Lawn Grass Disease

Understanding the conditions that give rise to a lawn grass disease will help prevent it from getting started. Common causes include:

  • Poor soil.
  • Lack of sunlight.
  • Grass seed not suited for climate and conditions.
  • Adverse weather conditions: excessive rain, ice, or heat.
  • Overuse of chemicals. (Use slow release fertilizer. Fast release promotes quick lush grass, which is susceptible to disease.)
  • Overwatering when the air is humid. Fungus thrives on wet roots.

If you need some expert advice, ask a local lawn treatment company. I like how you can sign up online for a free estimate.

Return from Lawn Grass Disease to Problems.