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First Report of Root Rot on Centipedegrass (Eremochloa ophiuroides) Caused by Gaeumannomyces graminis var. graminis.. H. T. Wilkinson, Department of Plant Pathology, University of Illinois, Urbana-Champaign. Plant Dis. 78:1220. Accepted for publication 17 October 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-1220A.

In 1994, extensive root rot was observed on the roots and crowns of centipedegrass (Eremochloa ophiuroides (Munro) Hack.) in central Georgia. The field was a sod production site, about two years old, and it had been established using sprigs. At the time of observation, the turf appeared to be knitted together to form a sod, but it was too weak to allow harvesting with a mechanical harvester. The turf (about 40 acres) displayed numerous areas with greater than 50% of the leaves necrotic, and at the border of these areas was a band (about 5-15 cm wide) delineated by yellow leaves. Symptomless turf areas were generally green, but the density of green leaves was 25-50% less than centipedegrass observed in other areas of Georgia, indicating that stresses additional to root rot may have contributed to the general decline of the turf. The roots, crowns, and stolons were extensively colonized by G. graminis var. graminis as determined by the presence of lobed hyphopodia, perithecia, asci, and asco-spores, and cultural characteristics on 1/5 potato dextrose agar (PDA) medium (1). The fungus was isolated from infected tissue, grown on 1/5 PDA, and used to inoculate centipedegrass sprigs. The sprigs were obtained from a field located 50 miles from the diseased turf, and upon inspection showed no disease symptoms or fungal colonization. The sprigs to be inoculated were stripped of all roots and leaves, rinsed in water several times, and inspected for any symptoms or signs of ecto-trophic fungi. Inoculated sprigs were incubated for 3 wk at 25 C and 5 wk al 30 C, washed free of soil and observed for infection on crowns and roots. Both the crowns and roots were colonized by G. graminis. The crowns were black and rotted, and the pathogen was isolated from the inoculated centipedegrass following surface sterilization with silver nitrate.

Reference: (1) M. L. Elliot et al. Plant Dis. 77:206, 1993.