1935, release from aquarium in Lake Michigan drainage (U.S. EPA 2008). Fanwort stems become brittle in late summer, which causes the plant to break apart, facilitating its distribution and invasion of new waterbodies. It produces seed but vegetative reproduction seems to be its main vehicle for spreading to new waters. Large numbers of plants are sent from Florida to the rest of the U.S. for commercial use. Fanwort is also grown commercially in Asia for export to Europe and other parts of the world. Small-scale, local cultivation occurs in some area and aquarists (aquarium release or escape) are probably responsible for some introductions.

Cabomba is sensitive to drying out and requires permanent shallow water, usually less than 3 meters (but up to 10 meters) deep. It grows rooted in the mud of stagnant to slow flowing water including streams, and smaller rivers. It also grows in ponds, lakes, reservoirs, sloughs, ditches, and canals.

It can respond to wide fluctuations in water depths and is a water column feeder that grows well in silty substrate and exhibits reduced vigour in hard substrates. Growth of 50mm a day has been reported in Lake Macdonald in Queensland, Australia. It grows well in high nutrient environments with low pH, but in more alkaline waters it tends to lose its leaves. High calcium levels inhibit growth and unlike other aquatic weeds, cabomba can grow well in turbid water.

It prefers a warm, humid climate with a temperature range of 13-27ºC but can survive when the surface of the water body is frozen.

C. caroliniana flowers from May to September. In the southeastern U.S., C. caroliniana is self-pollinating and seeds readily germinate.

Fanwort can form dense populations that interfere with recreation and clog drainage systems. It can grow from plant fragments, making it easier to spread.

When fed on my crayfish and snails, C. caroliniana induces a chemical defense mechanism deter both herbivores and microbes that typically attack plants via openings left by herbivores.

Grass carp, Ctenopharyngodon idella, will eat C. caroliniana, but it is not their preferred food source. Diploid or fertile grass carp are illegal for use in some states, such as Minnesota. The use of certified triploid or sterile grass carp is allowed is New York and Pennsylvania, with the correct permits.

Cabomba caroliniana becomes brittle late in the growing season. Physical control efforts should not be tried during this time because broken pieces can develop into new plants.

Physical cutting and removal: Most effective on large infestations in closed water bodies. In areas of sufficient size and depth, this can be done with floating mechanical. However, given the low probability of removing every plant fragment, this method is likely to only provide nuisance relief for a few weeks. Efficacy can be improved by using tools such as a venturi dredge, which acts like a vacuum cleaner to C. caroliniana fanwort fragments and the root ball.

Water-level drawdowns: have reduced growth of C. caroliniana populations in some areas in southern Wisconsin. Extreme drying, in which the root ball dries completely, is needed or the plant will return.

Ensuring wash-downs: of boats, trailers, and other equipment can reduce the spread of Carolina fanwort.

Precise application of appropriate herbicides to submerged C. caroliniana can be problematic and should be done with great care to avoid desired species.

Herbicides containing endothall or fluridone have been effective in controlling C. caroliniana. Carolina fanwort has also been reported to be sensitive to 4-D.

In laboratory tests, the application of diquat and flumioxazin (separately) resulted in a greater than 50% reduction in photosynthesis of C. caroliniana, however, these herbicides has not been tested in the field.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Global Invasive Species Database

Great Lakes Aquatic Nonindigenous Species Information