SPECIES DESCRIPTION: Curly leaf pondweed (Potamogeton crispus) is a rooted submerged aquatic invasive perennial plant. P. crispus is native to Eurasia, Africa, and Australia and is believed to have been introduced to the United States in the 1800s as an aquarium release or possibly as a related introduction when common carp were introduced to midwestern waters as game fish.
Curly-leaf pondweed starts growing in late winter/early spring which gives it a great advantage over native vegetation. When in full growth it forms dense mats that impede water recreation and can reduce waterfront property values. Starting in mid-summer, curly-leaf pondweed dies off causing large decaying masses; in turn, the decaying process reduces dissolved oxygen levels and increases phosphorous levels which can lead to algal blooms.
Curly-leaf pondweed can be easily spread by plant fragments or their rhizomes (rooted sections that grow in water bottom sediment). To prevent spread, it is important that boaters clean, drain, and dry their watercraft, trailers, and equipment before entering a new body of water.
Curly-leaf pondweed is widespread in waterbodies throughout the St Lawrence Eastern Lake Ontario region as well as other parts of New York State, to get current distribution data, visit NYiMapInvasives.org.
Curly-leaf pondweed can grow in shallow or deep waters typically to depths up to 15 feet. It can thrive in still or flowing waters, high or low light, and can tolerate cold temperatures.
Leaves/Stem: Leaves are approximately three inches long to a half-inch wide with edges that are wavy like the edges of lasagna noodles. Leaves are alternately arranged along the stem becoming denser at the top. Stems are flat and a reddish-brown color.
Flowers: Small greenish-red flowers grow on stalks that rise above the water surface typically in early summer.
Roots: Rhizomes are thick and pale yellow and rooted in water bottom sediment. Many plant stems can be connected to a single rhizome.
Curly-leaf pondweed can be removed by hand but can be time-consuming and labor-intensive. To reduce turion development, plants should be removed close to the sediment. The use of mechanical harvesters is less selective but can be an easier management option. Removal efforts should occur in the spring before flowering stalks appear above the water surface. To reduce the possibility of resprouting or spread, all plant fragments should be removed from the water and all remains should be disposed of away from the water’s edge.
Pesticides can be used to control curly-leaf pondweed and other macrophytes. Permits are required for chemical application in aquatic ecosystems and strict rules are in place for all label instructions to be followed. Learn more about pesticide use in New York State at the NYS Department of Environmental Conservation Pesticide Law and Regulation webpage and through the Cornell Cooperative Extension Pesticide Safety Education Program.
Tiploid sterile grass carp (White amur) can be used as a natural biocontrol method for curly-leaf pondweed in privately owned ponds that meet guidelines. These fish can be purchased from an approved state hatchery and require a special license from the NYS Department of Environmental Conservation.
Searching for invasive species populations in an effort to detect their presence before their populations become too large to manage is vital to reducing the impacts of invasive species on our natural ecosystems.
Click the link below to learn more about the species we’re enhancing early detection efforts for and to join our invasive species Volunteer Surveillance Network to aid this effort (training will be provided).
NYiMapInvasives is an online, collaborative, GIS-based database and mapping tool that serves as the official invasive species database for New York State.
Click the links below to become familiar with iMap