Minimize the amount of shallow areas where aquatic plants can root and grow abundantly. Mechanical control Hand removal Draglining and dredging Machine harvesting. Harvested weeds can be used as mulches or fertilizers. Weed harvesting is not suitable for removing plants from water less than 3 to 4 ft deep. Biological weed control has considerable potential in aquatic sites.
Copper sulfate is effective only for algae control.
Other types of herbicides must be used to control flowering aquatic plants. Applying the proper dosage involves accurate calculation of the surface area or volume of the body of water to be treated. Herbicide dosages are given in ppm. Labels usually provide the amount of chemical to be applied per acre-foot required to give the appropriate ppm of active ingredient. Most aquatic herbicides should be applied in mid- to late spring or early summer when plants are growing vigorously and there is less biomass to treat.