Disease Control

Lawn Diseases

Most lawn diseases are preventable by maintaining healthy, vigorous growth during the growing season. Water infrequently but deeply--too little water and/or frequent watering promotes shallow root growth and other problems.

Mowing your lawn on a regular basis and cutting only 1/3 of the grass blade helps to keep the thatch layer to a minimum. Aerating the lawn helps water penetrate deep into the soil, breaks down heavy thatch layers, and mixes nutrients, all of which help to develop a healthy lawn. Using a well-balanced fertilizer through the growing season is essential to maintain a thick, lush lawn.

Properly balanced pH soil levels allow the lawn to flourish; we recommend an annual application of lime to help maintain the correct pH level. Excessive thatch creates an excellent environment for disease and undesirable insects. Grassman can help prevent disease by aerating to manage your soil compaction and thatch. If a disease develops, a fungicide application may be needed, and we can help with that, too.

Dog Spots

Symptoms: Circular spots of brown grass, 8 to 10 inches in diameter, sometimes surrounded by rings of deep green grass.
Cause: Burned grass from dog urine.
Control: Limestone can neutralize the salt that causes the spot. Watering the area well and fertilizing promotes new grass growth. Common Diseases Found in Connecticut

Early Spring

Pink Snow Mold

This fungal disease is usually seen after the last snow melts. The affected area can range from a few inches to over a foot in diameter. Diseased areas are pale yellow at first, then become bleached or tan. Under ideal conditions (for the fungus!), the grass becomes covered with white mycelium that turns light pink with longer exposure to light. The fungus favors temperatures between 32 and 60 degrees Fahrenheit and becomes dormant above 70 degrees. Increasing air flow by removing limbs or trees helps deter this disease. Regularly raking leaves off the lawn in the fall also aids in prevention.

Gray Snow Mold

This disease is very similar to the Pink Snow Mold; however, the color is gray, and the fungus favors temperatures between 32 and 40 degrees. Increasing air flow by removing limbs or trees will help deter this disease. Regularly raking the leaves off the lawn in the fall will also aid in prevention.

Mid-Spring

Dollar Spot

This disease peppers the turf with bleach spots that may be light tan or gray with a red-brown border. Dollar spot favor the following conditions:

• 60 to 80 degree temperatures

• excess moisture

• heavy thatch

We recommend removing excess thatch, and then watering infrequently but deeply.

Red Thread

Symptoms of this disease are coral-pink to red fungus strands on the blades of grass binding leaves together. Affected turf areas are roughly circular and vary from 2 to 15 inches in diameter. When dry, the fungus strands resemble red threads. Red thread is most serious during periods of prolonged cool and wet weather. Water infrequently but deeply and only early in the morning so the foliage can dry quickly.

Summer

Pythium Blight

This disease is most destructive during hot, humid weather with temperatures of 80 to 95 degrees. Pythium blight can destroy large areas of turf in fewer than 24 hours. Over-watering, poor air movement and scalping the lawn will favor this disease. A fluffy white to grey fungus covers the affected area, usually in the morning. Water only in the morning, allow the leaves to dry, reduce fertilizer applications, and use preventive fungicide applications.

Brown Patch

Early in the morning, when the grass is wet, the affected area may be ringed by an area of dark, newly-infected grass. This "smoke ring" usually starts small but may spread to many feet in diameter. Affected leaf blades first appear water-soaked and dark. Leaf blades then wilt and become light brown as tissue dies. Conditions favoring this disease are excessive thatch, high humidity, high temperatures (between 75 and 95 degrees), and soft lush growth. Water deeply and infrequently, and only in early morning so the foliage can dry completely through the day. Reduce shade by pruning trees and removing heavy canopy to allow better air flow. Aeration is recommended for the thatch build up.

Fall

Rust

The first sign of rust is the development of light yellow flecks or lesions on the affected grass blades. As they grow, the leaf blades rupture and the classic rusty color develops as spores form. This mass of spores is easily spread by wind and traffic throughout rust-infected turf. Conditions that promote this disease are short periods of low light, high relative humidity and temperatures from 70 to 75 degrees. Lower humidity, higher temperatures and more light will help to eliminate rust.

Powdery Mildew

Powdery mildew first shows up as small light to grey patches of fungus growth, primarily on the upper surface of grass leaves. Patches rapidly enlarge and may involve the entire leaf surface. The underside of the leaf turns yellow then brown as the tissue dies. In severe outbreaks, the entire turf grass area appears a dull white. Shade, poor air movement and drainage, high relative humidity and temperatures around 65 degrees all promote powdery mildew.