There is currently no technique, short of dredging, to remove tubers from the sediment once they are formed. Herbicide treatm ents can kill vegetative parts of the plant but do not affect the tubers. Therefore repeated herbicide treatments are needed to eradicate hydrilla from a lake. Grass carp will readily eat leaves and stems of Hydrilla, but do not eat the tubers. No biocontrol agent has been found that can effectively attack tubers in areas with even mild winters.
Fanwort has distinctive fan-shaped submersed leaves arranged in pairs on the stem.
Distinctive, but small, floating leaves may also be present. The stem attaches to the floating leaf blade at the center where there is a slight constriction. Fanwort is a rooted aquatic plant with a limited distribution in the Northwest. In Washington it is restricted to side-channels of the Columbia River near Longview. In contrast to other rooted aquatic plants, fanwort is reported to obtain nutrients important for growth from the water column rather than the sediment.