Ricefield flatsedge, is in Holm's list of the world's worst weeds. An Asiatic species, it was probably introduced in the 1700 or 1800s. Rice flatsedge has become common throughout the southeastern United States. Cyperus iria is occasionally found in ditches, wet clearings, and margins of temporary pools in the peninsula, central and western panhandle. It blooms in the summer and fall (Wunderlin, 2003).
Once established in wet situations, ricefield flatsedge can persist without wet feet, and can become a major weed in rice, cotton, soybean and other crops.
For brief control information, see Efficacy of Herbicide Active Ingredients Against Aquatic Weeds by K. Langeland, M. Netherland, and W. Haller.