Lawn Diseases

Diagnosing lawn disease is a difficult process. There are many factors in the development of a lawn disease; poor aeration, insect infestation, poor soil quality, nitrogen imbalance, excessive shade or cutting and thatch. It is important to inspect the lawn regularly for signs of dysfunction.

Many factors of an unhealthy lawn promote disease and infestation. Dull lawnmower blades strip the tops of the grass – splitting them rather than making a clean cut. These tears make it easy for disease to invade the blade of grass while spreading to the entire lawn.

If the lawn is suspected to be diseased it is important to remove the clippings from the lawn after mowing. Allowing the clippings to remain will only allow the disease to spread. Clippings provide a healthy amount of fertilizer for the grass but only become a hindrance if infected with disease.

The two most prevalent fungal lawn diseases appear in the form of mushrooms and rust. Mushrooms are often caused by decaying matter in the soil such as wood. Rust appears as a rust coloured film on the underside of the blades of grass. Lawns that have been mowed too short or neglected are at risk of developing rust.

Mushrooms are not harmful to the grass in which they grow but become a discerning matter if ingested by children or pets. There is no way to properly identify a poisonous and non poisonous mushroom without knowing the species. Mushrooms become prevalent after a period of rain and are easily removed.

Rust disease may become noticeable while mowing as the grass emits a rust colored dust. This dust also becomes visible on shoes and clothing that come in contact with the lawn. Rust is easily prevented with adequate watering and fertilizing practises.

A lawn infected with mildew may appear to be greyish in color.  Mildew is often caused by a lack of sunlight and to eradicate the problem may require the removal of branches or overhead brush. Once the sunlight is able to reach the lawn the mildew should disappear restoring the lawn to its natural color.

Snow mould develops in the spring on lawns that have lingering snow and can be easily solved by removing the snow, and allowing the lawn to be exposed to the sun. Snow mould is identifiable by white patches of dead grass on the lawn.

Fairy rings are the most difficult of the funguses to remove from the lawn – as well as the quickest to contaminate the entire lawn. Fairy rings appear as dead grass in ring with living dark green grass on the outside of the circle. It is important to aerate the ring from the outside in with a pitchfork while cleaning the pitchfork after each use with rubbing alcohol. Aerate the lawn from seven to ten inches deep infusing the holes with soapy water for one week, than following with clean water for a period of two months. This should eradicate the problem. It is important that the soil or the matter from the fairy rings not come in contact with other parts of the lawn – as it is easily spread. 

Fairy ring infected areas may be treated with nitrogen rich fertilizer several times a year. At best this will mask the symptoms, but the unsightly rings may become less noticeable with treatment.

There are many preventative measures that one can take to lower the risk of diseased lawns. Be sure to mow the lawn to the recommended height, fertilize with nitrogen and aerate in the spring and in the fall and water deeply during the summer months. All of these combined measures will ensure that the lawn remains safe from disease.

For additional information on lawn care or related topics please visit our lawn care article center.