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Leaf Disease

What is Leaf Disease?

Leaf Disease Lawn Care

The disease spreads, in the form of spores, throughout your lawn by wind, air, water and humans. The disease may re-appear from year to year if conditions are met. Improper watering and mowing may cause the disease. Refer to Weed Man Mowing and Watering Fact Sheets for proper maintenance procedures. Discuss maintenance practises with your Weed Man.

Leaf Spot   (Helminthosporium spp.)

If your lawn is being watered and fertilized but still seems yellowish, it could be due to leaf spot disease. This disease is a fungus that attacks the blades of grass. Leaf spots are small circles with yellow centers and dark borders on, and along, the leaf blade. The disease can be a problem when the weather is cool and moist. Leaf spots occur most often in lawns that are mowed too short.

Dollar Spot    (Sclerotinia Homeocarpa)

Dollar Spot is a disease that can occur in lawns during warm weather. The fungus enters the grass plants when they are wet. Large tan colored wounds appear on the grass blades. These infected grass blades form rounded, damaged patches the size of a silver dollar. If the disease becomes more serious, the patches will expand and damage the entire lawn. Leaf spots are small circles with yellow centers and dark borders on, and along, the leaf blade.

Leaf Blight    (Ascochyta spp.)

Leaf Blight occurs on lawns during hot humid weather. The disease enters the grass plants after evening mowing, followed by excessive night watering. In heavily infested patches the fungus damages the lawn in circular or tubular patches that often form large bleached areas. Close inspection of the plant reveals individual leaves dying from the tip down with a brownish purple line running horizontally across the plant.


The best method of control is for the homeowner to alter the present lawncare practices. Avoid allowing water to sit on the grass overnight. Avoid mowing in the evening. Prune trees to encourage more air movement. Also keeping the thatch layer to less than ½” (1 cm) and proper fertility should be done to prevent the occurrence of these diseases. Promoting a healthy lawn is the key. In order to ensure everything is ok, have your local Weed Man advise you on correct lawn maintenance.