Identifying Turf Disease: Brown Patch, Lawn Rust, and More
Brown Patch
Brown Patch is a fungus — the Rhizoctonia solani fungus, to be exact. It penetrates the roots of your turf and is first visible as brown spotting on your grass blades. When left unchecked, it will turn the entire blade brown.
Brown Patch forms circular, or nearly circular, rings within your yard. Patches are irregular in size and shape and can be quite large. In the early morning when your turf is still wet with dew, you can discern a grayish “smoke ring” around the circumference of the Brown Patch areas.
Cooler temperatures, and when the season heats up — between 80 and 85 degrees Fahrenheit — the fungus spreads and becomes noticeable.
To prevent Brown Patch from invading your turf, maintain consistent watering and mowing and proper fertilization.
- Water your turf during the midday to prevent wet grass at night.
- Mow your turf to its ideal length on a consistent basis. This will promote air movement, and help blades dry properly.
- Use a moderate amount of nitrogenous fertilizer. Both over- and under-fertilization causes Brown Patch.
It’s also important to keep in mind, that while Brown Patch is a major cause of browning grass, it’s not the only cause. For example, stress due to lack of water can cause brown patches in turf. Consult a landscaping expert before attempting to treat your browning lawn.
Lawn Rust
Fortunately, Lawn Rust doesn’t affect the roots of your turf, but it does leave grass blades with a rather unpleasant orange “rusty” color. If you rub a handful of grass between paper towel pieces, blades infected with Lawn Rust will leave behind orange-colored blades and a powdery material.
Lawn Rust likes warm, dry, under-fertilized turf and usually develops in the late summer and early fall. Proper fertilization is your best line of defense against Lawn Rust. Aerating and seeding your turf in the fall can also help set it up for a successful summer next year.
Identifying turf disease can be a challenge. Download our Turf Disease E-book to help you identify and treat all types of lawn disease found in Tennessee.
Image Credit: Landscape Data Corporation
Dollar Spot
True to its name, dollar spot typically begins as small, distinct circles, about the size of a silver dollar. Because of the initial small size, it can be easy to underestimate the damage that dollar spot can do to a lawn. Dollar spot is a very thorough fungus, and kills the entire grass plant.
Low nitrogen fertility and low soil moisture are culprits for the spread of dollar spot. It can be prevented by fertilizing in late spring and watering for longer times, less frequently.
Red Thread
From a distance, Red Thread appears as pink to red patches from 4″ to 2 ft. in diameter. When observed more closely, you will see the reddish thread-like fungal structures on grass plants. When there is dew present on the lawn, you may even see small pink tufts on these spots as well. As the fungus grows, smaller spots may turn into larger ones as they connect together to form larger irregularly-shaped areas.
Fertilizing lawns in late spring and early summer will help to provide nitrogen. As that nitrogen gets watered in, most lawns will grow-out this specific turf disease problem. That being said, there are instances where Red Thread can become a chronic problem or advance past normal levels and a fungicide treatment may be required. This isn’t typical, but it can happen.