The best way to prevent a fungus problem is by maintaining a healthy lawn. Be careful not to over-water your lawn or water it at the wrong time of day. Here is a list of common lawn diseases found in Florida.
Brown Patch is most common to Bermuda, Kentucky Bluegrass, Centipede Grass, Bent Grass, St. Augustine, and ryegrasses in regions with high humidity and/or shade. Brown patch commonly starts as a small spot and can quickly spread outwards in a circular or horseshoe pattern up to a couple of feet wide. Often times, while expanding outwards, the inside of the circle will recover, leaving the brown areas resembling a smoke-ring.
Dollar spots are most common to Kentucky Bluegrass, Bent Grass, and Bermuda in humid climates. They get their name from their small silver dollar-like shape, but can begin as the size of a small grapefruit. Usually looks brown or straw-colored in appearance. The spots may merge to form large patches several feet wide.
Fairy Rings can grow in most grasses, and are distinguishable by circular rings filled with fast-growing, dark-green grass. Around the perimeter of the ring, the grass will typically turn brown and often times grow mushrooms. Fairy rings typically grow in soils that contain wood debris and/or old decaying tree stumps.
Rust gets its name from the orange, “rusty” appearance it gives leaf blades. Most commonly affecting ryegrasses and Kentucky Bluegrass, rust tends to flourish in conditions of morning dew, shade, high soil compaction, and low-fertility. The best way to check for rust problems is by taking a white tissue or paper towel and rubbing a few grass blades through it. If an orange color remains, then it’s usually rust.
Grease Spot can affect all grasses in humid climates and can be recognized by the slimy-brown patches that often have a white, cotton-like fungus around it. Grease Spot gets its name for the “greasy” appearance it makes while matting together and can appear in streaks across the lawn.
Red Thread is most common to Fescues, Ryegrasses, and Kentucky Bluegrasses during times of moist and cool weather. Red Thread gets its name from the pinkish-red threads that form around the leaf blades and bind them together. The red threads will be most visible when wet. Eventually, the affected grass will turn brown. The good news is Red Thread only attacks leaves and leaf sheaths and is seldom serious enough to kill a lawn.
Grass suffering from Powdery Mildew looks as though it is sprinkled with flour. Kentucky bluegrass and shady areas are most susceptible to this disease. But it is serious. Left untreated, eventually grass will wither and die.
You’ll notice irregularly shaded spots of wilted brown grass, as well as cobweb-like masses of fungi on moist nights or mornings. Patches cluster to form streaks a foot or more wide.
Lawns affected by Fusarium Blight will develop light green patches that spread, then turn reddish brown and eventually die.
The signs of this disease include brown to purple lesions (spots) on grass blades. Eventually, irregular dying areas of grass will form with lesions visible on the blades on the outer margins of dead area.
Like powdery mildew, slime mold covers grass with a powdery covering that looks almost like crystallized frost. Feeds on decaying organic matter found in the soil. As the powdery covering becomes thicker, it reduces the light reaching the plant cells, and they begin to turn yellow.