Leaf Disease

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What is Leaf Disease?

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 practices with your Columbus North, OH 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 in late Spring or Early Summer. Leaf spots occur most often in Kentucky Bluegrass (especially common bluegrasses) and fescue lawns that are mowed too short.

The leaf spot phase of the disease usually does not damage the plant significantly. However, during continuous cool, wet conditions, the fungus invades the leaf sheath and crown. The fungus also may invade the crown, rhizomes, and roots. As daytime temperatures increase, leaves on crown- infected plants begin to turn light green or yellow, similar to nitrogen deficient turf. Eventually these plants die and turn brown or straw colored. This is referred to as the melting-out phase of the disease. Severe melting-out can result in irregular patches of dead turf. Damaged lawns often appear "thin" or uneven and tend to have weed problems. Excess thatch, heavy spring nitrogen fertilizing, excess shade, mowing too close and excessive herbicide applications can promote leaf spot and melting out.


Leaf Spot Disease on Grass


Dollar Spot Sclerotinia Homeocarpa 

Dollar Spot is a disease that can occur in lawns (especially Kentucky Bluegrass) during warm weather. The fungus enters the grass plants when they are wet for extended periods of time.  The growth of this disease is inhibited when temperatures exceed 90 degrees F.  Turfgrass growing in dry soil conditions is more susceptible to this disease than turf growing with adequate soil moisture, thus proper irrigation is helpful.  Damage is also more pronounce in areas with Nitrogen deficiency your Columbus North, OH Weed Man will provide the necessary amounts of fertilizer to strengthen your lawn.

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.

Dollar Spot on Lawn


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.
 

 

Leaf Blight on Grass


Control

The best method of control is for the Ohio 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.

 
Have your Columbus North, OH Weed Man advise you on correct lawn maintenance.
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