LEARN YOUR LAWN: Necrotic Ring Spot

What Is Necrotic Ring Spot?

Necrotic Ring Spot is a fungal disease in the soil that affects cool-season turfgrass, such as Kentucky Bluegrass, Perennial Ryegrass, and Fine Fescue. It results in circular patches of dead grass that have a distinct brownish-yellow ring surrounding a healthy-looking center. The rings can vary in size, but are generally about a foot in diameter. It’s sometimes called “Frog Eye” because of the shape of the rings.

Although the symptoms of Necrotic Ring Spot are most apparent during the cool conditions of the spring, when the fungus is active, symptoms can appear throughout the growing season. The disease is often intensified by stress from heat and drought conditions, so symptoms generally reappear during the hot, dry summer months. It’s important to stick to proper cultural practices to reduce the chances of significant damage to the turf.

How Can I Control Necrotic Ring Spot In My Lawn?

Necrotic Ring can be difficult to control. In some cases, you may be able to remove the affected soil and re-seed or sod the area with a more disease resistant variety of grass. However, depending on the size of the infestation and the scope of the damage, other forms of control may be necessary. 

A thick, healthy, well-maintained lawn is the best line of defense. Here’s how you can adjust your beneficial cultural practices to reduce the spread of Necrotic Ring Spot:

• Avoid Watering: Under normal circumstances, you should be watering each area of your lawn for 30-45 minutes, twice per week, in the early morning so the turf is dry by nightfall. However, you should avoid watering when the disease is active.

• Mowing: You should avoid mowing when the disease is active. If you do have to mow, make sure your mower blade is razor sharp, so that the blade does not fray the tips of the grass, spreading the disease. Maintain a regular mowing schedule throughout the growing season. In general, you should keep your lawn between 2 ½ and 3 ½ inches high, but during the hottest weeks of summer, you may allow the grass to grow as high as 4 inches. Never remove more than ⅓ of the grass blade at each mowing.

• Fertilize Regularly: Regular applications of Weed Man’s specially formulated, slow-release granular fertilizer will help provide your lawn with adequate nutrients. These applications are timed specifically to avoid over fertilizing the lawn.

• Core Aeration: Aerating your lawn can improve soil drainage and help reduce the likelihood of lawn diseases. This will also alleviate soil compaction and allow water and nutrients to penetrate deeper into the soil.

Your local Weed Man professional may be able to offer other solutions and recommend the best form of treatment that is available to improve the conditions of your lawn.