Both purple and yellow nutsedge (Cyperus rotundus L. and C. esculentus L.) are problem weeds in crops in many parts of the world (18). Yellow nutsedge is found in all of the United States. Purple nutsedge is confined to the southern region of the United States, ranging from North Carolina across southern Arkansas and into southern California (32).

In the southern states, reports citing nutsedges as troublesome weeds do not always differentiate between yellow and purple nutsedge (20). The two species may be found growing in the same general area and are difficult to distinguish before flowers appear. Usually yellow nutsedge is found on low, moist areas, while purple nutsedge is found on well-drained soils (18). Under optimum growing conditions, purple nutsedge is more vigorous and competitive than yellow nutsedge (1).