Like other varieties of plants, grass can suffer from diseases and damaging conditions. Although lawns are comprised of numerous, individual grass plants, large expanses can quickly die when diseases spread from one small plant to others, often affecting the whole lawn. Early recognition and management of developing diseases may save an entire lawn from succumbing. Yellow patch, one common type of mildew disease that affects lawn grasses, requires quick treatment to keep it from spreading and ruining your lawn.
Learn to recognize the presence of yellow patch disease in your lawn. Look for irregular patches that reach up to 3 feet in diameter. Notice yellowing grass that forms a circle around sections of greener grass. Check your lawn during damp, cool weather in the fall and spring. These symptoms may also appear in the winter months in climates where the grass does not become dormant.
Limit the amount of water you apply to your lawn as soon as you notice the appearance of yellow patch. Allow the surface of the soil near the blades of grass to become dry before watering. Do not water your lawn after a rainfall or when the weather forecast predicts rain, especially during periods of cool weather. Water your lawn just once each week during dry periods, allowing the water to soak into the top 6 inches of soil. Avoid shallow, frequent watering sessions that may cause this disease to spread.
Remove the thatch in your lawn to allow healthy amounts of air to flow around the bases of the grass blades. Thatch is a layer of debris on the surface of the soil that contains dead particles of grass and leaves. Rent a vertical mower to pull this layer of vegetative debris out of your lawn. Run the vertical mower back and forth over your lawn in accordance with the manufacturer's instructions to remove thatch in every section of your lawn.
Apply a fungicide designed for use on your type of lawn grass, but use this method to only if the other methods do not eliminate the yellow patch. Apply the fungicide in mid April to early May, or as directed on the package instructions for your variety of lawn grass.