Your lawn is your little piece of the earth. You own it; you care for it, and you’re responsible for it. What do you do when your lawn starts turning red, yellow, or brown? Most likely, you’re looking at a lawn disease, specifically a fungal disease. However, lawn disease can be treated when you diagnose it correctly and follow the right plan.
Once you learn how to identify lawn disease, you’ll be pleased to know that you can once again achieve a beautiful front yard, back yard, and side yard – a healthy lawn that your neighbors will admire.
Fungal diseases kill of large swatches of your lawn, which is why they’re called patch diseases. Advanced stages of the disease appear as rings of dead turf surrounding living turf that resemble a “frog’s eye”.
Patch diseases generally occur on sodded lawns, especially within the first 5 years of establishment. However, older lawns either established from seed or sod can also develop patch diseases. Once established, these diseases are extremely difficult to control and tend to occur in the following years. These diseases can occur on any turfgrass but are the most damaging to Kentucky Bluegrass.
Initial symptoms appear as small spots of light green turf with a diameter of two to four inches. The spots grow to form colored circles, irregular patches, and crescent patterns that are one to two feet in diameter.
Centers of the patches may contain grass that is alive or dead. When the center grass is dead, the patches appear crater-like or sunken. Patches may overlap to form large areas of blighted turf. Symptoms may also appear as diffused patterns of yellow or brown turf. You may also see blackened crowns, rhizomes, and roots.
Researchers have identified several fungi that cause patch-like symptoms. Here are the most common fungi that cause lawn disease.
Nectrotic Ring Spot
Necrotic ring spot (leptosphaeria korrae) thrives in cool, wet conditions, which occur primarily in the spring and fall. Although necrotic ring spot is active during cool weather in the spring and fall, you may also see patches in the summer months.
Yellow patch (Rhizoctonia cerealis) also prefers cool, wet conditions, which occur primarily in the spring and fall. Like a necrotic ring patch, you may see a yellow patch in the summer if it isn’t treated properly during the spring or fall.
Summer patch (magnaporthe poae), as you can guess from its common name, is active during the summer period. Summer patch thrives in hot, humid conditions.
Controlling Lawn Disease
Controlling lawn diseases is can be difficult. Properly maintaining your grass will reduce damage by patch diseases. When installing a lawn, properly prepare the soil and select good quality sod or grass seed. Aerating your lawn in the fall will help the grass root more effectively, which will help prevent lawn disease. If your grass is too far gone, you may need to renovate your lawn.
Here are recommendations for controlling lawn disease.
- Mow frequently at 2 1/2 to 3 inches in height.
- Water your lawn frequently without drowning it.
- Keep thatch to a minimum.
- Reduce soil compaction by aerating your lawn.
Note: fungicides alone generally do not provide satisfactory control of patch diseases.
Red Thread and Pink Patch
Red thread and pink patch are diseases that attack Kentucky bluegrass, fescues, ryegrass, and bentgrass. These diseases thrive when there are prolonged periods of high humidity, with temperatures between 60°F to 75°F and your lawn is slow-growing with nitrogen-deficient turf. If a red thread is present, you’ll see grass that’s covered with a pink, fibrous growth. In the final stage, reddish fungal threads are found at the leaf tips.
Pink/red areas can be 2 to 15 inches in diameter when a lawn is infested with red thread or pink patch. These patches can grow to form large areas of damaged turf. Eventually, those patches may turn brown and dry out if they aren’t treated properly.