Necrotic Ring Spot DiseaseNecrotic Ring Spot Disease

Necrotic ring spot frequently occurs on two to five-year-old sodded lawns and is especially prevalent in vigorously growing lawns. These lawns often develop a thick thatch layer, which stimulates fungal growth. Necrotic ring spot is also common in lawns that have layered soil; one to two inches of topsoil laid down over hard compacted native soil, but not mixed together. This effect produces a lawn with shallow roots and poor drainage. The development of the “frog’s eye” lesions are tell-tale signs of the disease’s presence. Necrotic ring spot can be problematic, but implementation of proper cultural practices can manage this disease. Lawns that are compacted or have thick thatch layers promote the development of necrotic ring spot. Fungicides are available that manage the disease preventative, but are of limited use once disease symptoms are visible. However, if cultural deficiencies are not corrected, necrotic ring spot may persist in a lawn for many years. Kentucky bluegrass and fescue are the most common species of grass infected. Proper mowing, watering, soil aerification and keeping thatch buildup to a minimum are all important keys