Summer Patch
Necrotic Ring Spot
Summer Patch
Necrotic Ring Spot and Summer Patch are two different fungi with essentially identical symptoms. The difference is the time of season that they are active. These are both common and serious diseases of Kentucky bluegrass sod that are about 2–4 years old. They affect the roots of the grass. They do not attack bentgrass nor ryegrass.
Necrotic Ring Spot (NRS) is active during the spring and fall in wet weather. Summer patch is active in hotter weather.
Initial symptoms are rings of wilting turfgrass, which develop during the heat of the day. These will often go unnoticed until the wilted rings turn brown, creating “frog eye” patterns scattered throughout the infected area. Since the roots are what are typically attacked, there are no apparent lesions on the leaves.
These diseases are so common in bluegrass sod that we’ll often implement a fungus control program before the disease is even apparent.
Avoid excessive application of water-soluble forms of nitrogen before periods of high heat. As they are in managing all diseases, proper mowing and watering are important.
We can apply fungus controls for more serious cases. Bear in mind that fungus control applications are not a complete cure. They simply control it for a period of about 1 month.
