Physically cutting Arrowhead and digging up the roots can be a somewhat successful way to manage this plant, but Arrowhead can regrow from any remaining roots or seeds.
Imox herbicide and a Surfactant will effectively control Arrowhead. These products together are called our Cattail and Water Lily Control. Another product that will control Arrowhead is 2, 4-D. Thoroughly wetting the plants in late summer or early fall is the most practical time to treat. This is when Arrowhead plants are directing their energies to the root system, which helps pull the herbicide down to the roots to kill both those and the vegetative portions.