Ustilago esculenta is a species of fungus in the Ustilaginaceae, a family of smut fungi. It is in the same genus as the fungi that cause corn smut, loose smut of barley, false loose smut, covered smut of barley, loose smut of oats, and other grass diseases. This species is pathogenic as well, attacking Manchurian wild rice (Zizania latifolia), also known as Manchurian ricegrass, Asian wild rice, and wateroat. This grass is its only known host.