Common Grass Diseases

By Clément André, last updated at 2012-01-7

Snow mold can be identified just after the snow melts on the lawn. There are two types of snow mold: gray snow mold, Typhula blight or, and pink snow mold or Fusarium patch. Gray snow mold causes the grass to turn straw color with gray mold growing on the surface. Pink snow mold will make the lawn look bleached with more pink mold on top. You can prevent both types of snow mold by keeping the lawn mowed in the fall. Fungicide can be applied on lawns with a history of snow mold.

Gardeners can see signs of rust where the summers are particularly hot. Rust spreads rapidly when air temperatures are between 85 to 95 degrees Fahrenheit, according to North Dakota State University. This disease causes the grass to turn yellow-orange to red. You may be able to control rust by applying the right amount of fertilizer and water for the lawn. Keep the grass to its recommended height will help keep the blades in good enough health to fight disease.

The stain is caused by fungal spores called Bipolaris sorokiniana. This disease is one of the most destructive evils for bluegrass, according to North Dakota State University. You can see spots in the yard that are purple on the edges and tan in the center. If left untreated, fungal disease can spread down to the root system or "melt". Once it is in the root system, the blade of grass and roots can all die. Treat the stain with a fungicide when you first see signs of the disease.

Types of cool season grasses like fescue, and ryegrass and bluegrass are very susceptible to brown spot. Gardeners should look for brown areas that are 6 to 12 inches in diameter, according to Cornell University. Grass will tanning centers with brown edges. Thatch or thatch which is 1/2 inch thick may promote brown patch. Applying too much nitrogen to the lawn will also weaken the grass and cause brown spots. A fungicide can be applied to treat the lawn.

Unhealthy lawns are particularly susceptible to a common lawn disease. Thatch, poor fertilization and moist soil health contribute to the decline of a lawn, leaving them vulnerable to a disease of weed. Diseases such as brown patch, leaf spot, rust and snow mold can infect the grass and leave bare spots or entire lawn in trouble with the disease, according to Cornell University.

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