NRC Symptoms Show

 After Labor Day in the northern United States, necrotic ring spot symptoms are still apparent.  Necrotic ring spot caused by the fungus Leptosphaeria korrae is a serious disease of Kentucky bluegrass. Initial symptoms appear as reddish brown to straw colored grass blades. The disease rapidly progresses to circular patches of straw-colored grass. Within the patch healthy grass or broadleaf weeds colonize the center. These circular patches are showing in many homelawns at this time. The disease is most common on Kentucky bluegrass lawns that have a thick thatch layer that has developed on a compacted soil green. Once this disease appears it will normally appear in subsequent years. At this time of the year thatch removal/reduction should be attempted.  Fertilizing to promote turf recovery would also be recommended.  If the patches are severe to the point where they have coalesced and blighted a large area of turf, overseeding these areas may be necessary.  Fungicide applications are effective for controlling necrotic ring spot, but are best applied during the spring when the fungus is actively attacking the root system.

 

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