Golf Course Management

AUG 2018

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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68 GOLF COURSE MANAGEMENT 08.18 1 inch to 6 inches (2-15 cm). As the disease progresses, the spots coalesce to form large, ir - regular areas of blighted turf (Figure 2). e leaves of affected plants initially display small, purplish-black spots that develop into distinct eyespot lesions with necrotic, dark brown cen - ters surrounded by dark brownish-black mar- gins (Figure 3). e older blighted leaves in the lower canopy of the turf give rise to the chocolate-brown-to-black spots observed in the turfgrass stand. Spots resulting from fall epidemics may remain conspicuous within the dormant turf, maintaining the sooty black ap - pearance until spring green-up (Figure 4). Ink spot is most prevalent in the spring and fall, which are transition periods for bermu - dagrass and zoysiagrass, but the disease may persist into the summer months that follow prolonged or significant precipitation events such as tropical storms or hurricanes. Ink spot, also known as Curvularia blight or dog's foot - print (inu no ashiato; Japanese translation), are turfgrass diseases caused by the same patho - gen, C. malina, as Micah Woods, Ph.D., con- cluded in the Asian Turfgrass Center Blog (3). Climate Anecdotal sightings and a published first report (Hainan Province, China) of disease caused by C. malina appear to indicate that diseases caused by C. malina are geographi - cally confined to regions influenced by the subtropical ridge associated with 30ÂșN. e 30th parallel north is considered arid to semiarid, but locales in that area that are influenced by large bodies of water have a more tropical environment and form what is called the "subtropical ridge." ese regions include the Gulf and Atlantic United States, South China, southern Japan and southern Queensland, Australia. Currently, no reports of ink spot have been made outside the 30th parallel north. Host species To conclude the characterization of C. ma- lina and ink spot, a host-range study of warm- season turfgrasses was conducted at Missis - sippi State University. In greenhouse studies, zoysiagrass was more susceptible than all the other warm-season grasses evaluated, includ - ing bermudagrass. Centipedegrass and St. Augustinegrass developed foliar lesions, but foliar leaf blight was not extensive. Seashore paspalum did not develop foliar lesions, but shoot and root dry weights were significantly Figure 2. (Top) Foliar symptoms of ink spot on a zoysiagrass fairway. A. Ink spot first appears as chocolate- brown-to-black spots, less than 1 inch to 6 inches (2-15 cm). B. Under ideal disease conditions, ink spot symptoms may coalesce, creating large areas of mottled brown to black turf. Photo by Billy Weeks Figure 3. (Center) Foliar symptoms of ink spot caused by Curvularia malina include conspicuous elliptical lesions with black margins on zoysiagrass. Lesions may expand across and down the leaf to cause blight. Photos by Maria Tomaso-Peterson Figure 4. (Bottom) During fall epidemics of ink spot, black, sooty patches may remain in the turf canopy throughout dormancy and recur during spring green-up.

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