Photographer: Leslie J. Mehrhoff, University of Connecticut Source: Bugwood.org Copyright: CC 3.0 US
Curly pondweed is a perennial aquatic plant that gets its name from the rippled submerged leaves. The leaves are alternate, oblong, ¾ to 4 inches long and ¼ to ½ inches wide. Flowers are on a short stem that rises above the water’s surface, and seeds are also produced.
Potamogeton crispus can form dense mats and inhibit the growth of native species through the reduction of oxygen and sunlight. Furthermore, it can hinder boating and other recreational activities.
For a submersed aquatic plant, curly pondweed has a unique life cycle. Most plants come out of their dormant phase in the early parts of spring. However, this plant comes out of dormancy in late summer, which allows it to evade competition with other plant species. Once it is no longer dormant they produce turions which are thickened shoot segments that can fragment off and become new plants. This plant is also able to reproduce by seeds and rhizomes. While the seeds are quite fertile, the most successful means of reproduction for curly pondweed is through rhizomes.
It was accidentally introduced to the northeastern United States in the 1840s, possibly due to fish stocking operations. It was found in California in the 1880s. Now it is found in all of the contiguous United States.
Eurasia, Africa and Australia
U.S. Habitat: warm lakes and streams
U.S. Present: All states except Alaska and Hawaii
For a distribution map provided the EDDMapS click here.
In order to control curly pondweed by physical methods one has make sure that all of the turions are also being eliminated. However, with how quickly turions can disperse in the water, this is long-term management plan. These practices should be does in spring or early summer, before the plant exits its dormant phase. Some research has shown that seasonal cutting of pondweed down at the sediment surface can prevent the production of turions.
Only a few herbicides can be used to control curly pondweed, such as Endothall, Diquat and Fluridone. USE PESTICIDES WISELY: Always read the entire pesticide label carefully, follow all mixing and application instructions and wear all recommended personal protective gear and clothing.
Researchers are working on biological controls, and have found some success with the grass carp, but there are some drawbacks with introducing the grass carp to new habitats.
Catling, P.M. and I. Dobson. 1985. The biology of Canadian weeds: 69. Potamogeton crispus L. Canadian Journal of Plant Science 65(3):655-668.
Curlyleaf Pondweed - Invasive Species Fact Sheet (Sep 2007; PDF | 1.09 MB)
Mississippi State University. GeoResources Institute.
McComas, S. and J. Stuckert. 1996. French Lake (Rice County) curlyleaf pondweed control using a boat-towed cutter, 1996: Status Report. Unpublished report submit-ted to Rice County Environmental Health Department and the French Lake Association by Blue Water Science, 550 S. Snelling Av., St. Paul, MN 55116. 22 pp
Nichols, S.A. and B.H. Shaw. 1986. Ecological life histories of the three aquatic nuisance plants, Myriophyllum spicatum, Potamogeton crispus and Elodea canadensis. Hydrobiologia 131(1):3-21.
Poovey, A.G. and J.G. Skogerboe. 2002. Spring treatment of diquat and endothall for curlyleaf pondweed control. J. Aquat. Plant Manage. 40:63–67