Necrotic Ring Spot Disease of Turfgrass in Wisconsin

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Abstract
A dark, ectotrophic fungus was consistently found in association with rotted crowns and roots of turf affected by a disease of uncertain cause. Symptoms were variable, but necrotic rings and patches predominated, and the disease was named "necrotic ring spot." Kentucky bluegrass was the primary host affected, but the organism was also isolated from other grasses. The fungus was isolated on several media, but the most consistent results were achieved after the tissue was washed and surface-disinfected, dried for 18 hr, then plated on potato-dextrose agar plus novobiocin. Pathogenicity was demonstrated on Poa pratensis and P. annua sod plugs and on seedlings of several members of Gramineae. A teleomorphic stage developed on inoculated roots of wheat, oats, and perennial ryegrass and has been tentatively identified as Leptosphaeria korrae.