Besides Rodeo and Eagre there is a cheaper formulation of Glyphosate with the same concentration or percentage of the active herbicide. Another important consideration is to treat when the seed heads are formed in mid to late summer. This is the point when the plant begins to store energy in the root and is drawing it in instead of using the stored energy in the root for growth and reproduction. Like the others said use plenty of surfactant, coat the entire visible plant, and cut the stalks below the water line when entirely dead. fishmgr@hotmail.com