Identification: When Leaf Spot infects your lawn, spots will appear on your leaf blades that have purpilish-red to purplish-brown edges with brown or tan centers. While spots might extend the entire width of the blade, they are typically somewhat longer than they are wide. If the infection is severe enough, the grass leaves will turn entirely reddish-brown and then wither and die. The crowns and roots of infected grass can also become dark brown with rot. When the grass is crown-infected, it may end up dying in hot, windy weather, which will leave many thinned out areas in your lawn.
Cause: The spores of the organisms that cause this disease are windborne, so it is very easy for your lawn to become infected. This disease also thrives in areas where there are warm temperatures (from 70-90 degrees) and high humidity. High amounts of nitrogen in the soil as well as a closely clipped lawn can also contribute to the likelihood of this disease affecting your lawn.
Prevention:
- Reduce shade, where possible
- Aerate your lawn and improve its water drainage
- Water your lawn evenly, preventing dry spots
- Practice good watering practices, preventing frequent, excessive watering
- Fertilize appropriately for your lawn, avoid adding too much nitrogen
- If possible, try to maintain a higher cutting height
- Avoid herbicide applications when the disease is active
- Keep thatch build-up under control, remove when it becomes excessive
Treatment: Fungicides can work well in helping your lawn recover from a Leaf Spot infection. They cannot achieve the best results on their own, however. If your lawn has become infected with this disease, it is recommended that, on top of fungicide application, you should change your lawn maintenance procedures to help prevent future outbreaks and to help your lawn recover from its current state. Planting grass types that are resistant to this disease when you begin your lawn or if you have to reseed is also advised.
Grass types susceptible:
- Bluegrass
- Fescue Grass
- Ryegrass
- Zoysia Grass
