Cylindrosporium eleocharidis is described as a new species on Eleocharis dulcis in Georgia. Alternaria sp., the endoconidial staze of Ceratocystis paradoxa, Cladosporium herbarum, Curvularia lunata, C. maculans, Epicoccum nigrum and Pestalotia scirpina are reported for the first time on E. dulcis planted in the United States. All except C. paradoxa and E. nigrum were previously unreported on that host anywhere. All except Alternaria sp. are described briefly and illustrated. Eleocharis dulcis (Burm. f.) Trin. (syn.: E. tuberosa Schult.) is a tropical sedge with long, spikelike, leafless green stems and crisp, fleshy, edible corms. Cultivated for many years by the Chinese, this species recently was brought into the southern United States, where it was planted on a small scale for sale especially to restaurants. Hodge and Bisset (1955) described the cultivation and utilization of E. dulcis and called it the Chinese waterchestnu,t to distinguish it from the unrelated common waterchestnut, Trapa natans L. The refer to E. dulcis as matai. Hodge and Bisset mentioned only one fungus disease of waterchestnuts planted in the United States. That seemed to be caused by a species of Cylindrosporium (Figs. 1, 2) that attacked the stems of plants growing on highly acid soil. The report by Hodge and Bisset apparently is the first record of a Cylindrosporium on any species of Eleocharis. Material with this fungus was collected in abundance in 1953 by D. A. Bisset, Superintendent of the U. S. Plant Introduction Garden, Savannah, Georgia. This material, deposited in the National Fungus Collections, also bears several o,ther fungi evidently developed as secondary molds that did not cause disease. Relatively few fungi are reported as occurring on any of the 40 species of Eleocharis described in Gray's Manual (Fernald, 1950) or the approximately 135 species in the Index Kewensis (Hooker and Jackson, 1895). The list includes Mucor circinelloides v. Tiegh. (cf. Tai, 1936), Physoderma heleocharidis (Fckl.) Schroet., Phytophthora sp., Pythium spinosum Sawada (cf. Matsumoto, 1955), Zygorhynchus japonicus Kominami (cf. Hunt, 1958), Ceratocystis paradoxa (Dade) C. Moreau, C. adiposa (Butl.) C. Moreau (cf. Davidson, 1935; Hunt, 1956), Claviceps nigricans Tul., various species of Leptosphaeria, Meliola, Melanospora, Mycosphaerella, Pleospora, Pyrenopeziza, and Sclerotinia, Puccinia eleocharidis Arth., P. liberta Kern, Uromyces eleocharidis Arth., Uredo incomposita Kern (cf. Kern, 1919), several species of smuts (cf. Ling, 1953), and species of Ascochyta, Cladospori1Mailing address: Mycology Investigations, Plant Industry Station, Beltsville, Maryland, U.S.A.