[Curly, curly-leaved, crispy-leaved, crisped] pondweed

The unique seasonal phenology of P. crispus differentiates the species from other submersed aquatic plants found in North American waters.  In the colder regions of its range, turions (the primary reproductive propagule) break dormancy in the fall when water temperatures drop (Nichols and Shaw 1986). P. crispus survives the winter as whole, intact leafy plants (even under thick ice and snow cover) (Stuckey et al. 1978), then grow rapidly in early spring when water temperatures are still quite cool (10-15°C).  In early June plants flower, fruit, and form turions, and then plants senesce by mid-July (Tobiessen and Snow 1983) in most areas of its range.  The winter growth form of P. crispus is morphologically different from its spring or summer growth form, with leaves that are flattened, narrow, and blue-green in color with few stems and thin rhizomes (Tobiessen and Snow 1983).

State occurrences:

• Alabama: Cahaba (University of Alabama Biodiversity and Systematics 2007), Guntersville Lake, Mobile-Tensaw (Stuckey 1979), and Middle Alabama (Zolczynski and Shearer 1997) drainages, and DeKalb County (Haynes 1980)
• Arizona: Little Colorado (Stuckey 1979), Lower Colorado, San Pedro-Wilcox, Verde (Arizona State University 2003), Lower Colorado-Lake Mead, Lower Gila, and Santa Cruz (University of Arizona Herbarium 2008) drainages
• Arkansas: Benton County (Smith 1988)
• California: All drainages except Black Rock Desert, North Lahontan, Oregon Closed Basins, and Walker (Consortium of California Herbaria 2014; Stuckey 1979)
• Colorado: Evergreen Lake in South Platte drainage (Stuckey 1979), and Dinosaur National Park in the Green River in Upper Green drainage (Utah State University 2007)
• Connecticut: Connecticut Coastal, Lower Connecticut, and Lower Hudson (University of Connecticut 2011) drainages
• Delaware: Wilmington in Brandywine-Christina drainage (Stuckey 1979)
• District of Columbia: Middle Potomac-Anacostia-Occoquan (Smithsonian National Museum of Natural History 2015) drainage
• Florida: Jackson Blue Spring in Chipola drainage (Stuckey 1979), and Lake Jesup in Upper St. Johns drainage (Wunderlin and Hansen 2007)
• Georgia: Lake Seminole in Lower Flint (Stuckey 1979) and Spring (Gholson 1968) drainages, and Rock Eagle Lake in Upper Oconee drainage (University of Florida Herbarium 2016)
• Idaho: Idaho Falls, St. Joe (Falter et al. 1974), Lower Bear (Tom Woolf, ID Dept. of Ag., pers. comm.), Middle Snake-Boise (New York Botanical Garden 2015), and Pend Oreille drainages, and Washington County (Rice 2008)
• Illinois: All drainages (Center for Invasive Species and Ecosystem Health 2015; Loyola University Chicago 2013; Stuckey 1979)
• Indiana: All drainages (Aquatic Control, Inc. 2007; Aquatic Weed Control 2007; Central Hardwoods Invasive Plant Network 2010; IN DNR 1997; Miller 2016; Stuckey 1979)
• Iowa: Apple-Plum (Loyola University Chicago 2013), Big Papillion-Mosquito, Upper Wapsipinicon (University of Kansas Biodiversity Institute 2008), Coon-Yellow (Beal and Monson 1954), Copperas-Duck (Stuckey 1979), and Little Sioux (Weisman 2016) drainages, and Monona County (McGregor and Barkley 1977)
• Kansas: All drainages (Jason Goeckler and Jessica Howell, KS DWPT, pers. comm.; Stuckey 1979; University of Kansas Biodiversity Institute 2008)
• Kentucky: Smokey Valley Lake of Carter Caves State Park in Little Scioto-Tygarts drainage, and Boone, Bracken, Gallatin, Henderson, and Madison Counties (Beal and Thieret 1986)
• Louisiana: Eastern Louisiana Coastal, Lake Maurepas, Lower Mississippi-New Orleans drainages (Chabreck and Condrey 1979; Stuckey 1979)
• Maine: West Pond in Saco drainage (Madsen et al. 2010)
• Maryland: Lower Susquehanna (Mercurio et al. 1999), Potomac, and Upper Chesapeake (Stuckey 1979) drainages
• Massachusetts: Connecticut Coastal (Hellquist 1972), Lower Connecticut, Massachusetts-Rhode Island Coastal (University of Connecticut 2011), and Merrimack (Acadia University 2012) drainages
• Michigan: All drainages except Northeastern Lake Michigan and Southeastern Lake Superior (GLIFWC 2008; Michigan State University 2015; Stuckey 1979; University of Alabama Biodiversity and Systematics 2007; University of Connecticut 2011; Voss 1972)
• Minnesota: Minnesota (Anderson 2016), Mississippi Headwaters, Rainy, Upper Red (Balgie et al. 2010), Northwestern Lake Superior, Upper Mississippi-Black-Root, Upper Mississippi-Crow-Rum (Stuckey 1979), St. Croix (GLIFWC 2008), and Upper Mississippi-Maquoketa-Plum (Utah State University 2007) drainages
• Mississippi: Davis Lake of Tombigbee National Forest in Tibbee drainage (Dennis Riecke, MS DWFP, pers. comm.), and Trace State Park Lake in Town drainage (Madsen 2010)
• Missouri: Big (Center for Invasive Species and Ecosystem Health 2015), Current, Eleven Point, Lower Missouri, Upper Grand, Lower Missouri Blackwater (Missouri Botanical Garden 2007), Meramec, Spring (Stuckey 1979), and Peruque-Piasa (Loyola University Chicago 2013) drainages, and Pike County (Yatskievych 1999)
• Montana: Marias, Upper Missouri (Center for Invasive Species and Ecosystem Health 2015), Missouri Headwaters (Utah State University 2007), and Pend Oreille (Rice 2008) drainages, and Valley County (McGregor and Barkley 1977)
• Nebraska: Hayes Center WMA lake shore of the Red Willow drainage (University of Kansas Biodiversity Institute 2008) and Bridgeport State Recreation Area in Middle North Platt-Scotts Bluff drainage, and Cass, Dodge, Pawnee, and Valley Counties (McGregor and Barkley 1977)
• Nevada: Nevada - Carson Desert, Truckee (New York Botanical Garden 2015), Long-Ruby Valleys (Utah State University 2007), Potomac (Delwiche 2001), and Pyramid-Winnemucca Lakes (Stuckey 1979) drainages
• New Hampshire: Black-Ottauquechee, Nashua (NH DES 2015), Middle Connecticut (IPANE 2001), Piscataqua-Salmon Falls, Upper Connecticut-Mascoma (Padgett and Crow 1993), and West (Center for Invasive Species and Ecosystem Health 2015) drainages
• New Jersey: New Jersey - Lower Delaware, Raritan (Stuckey 1979), and Middle Delaware-Musconetcong (Schuyler 1989) drainages
• New Mexico: Isleta of Tena Indian Reservation in Rio Grande-Albuquerque drainage (Stuckey 1979)
• New York: All drainages (iMapInvasives 2015; Scott Kishbaugh, NY DEC, pers. comm.; Michigan State University 2015; Mills et al. 1993; Stuckey 1979; Titus 1994; University of Connecticut 2011)
• North Carolina: small stream at state fish hatchery near Marion in Upper Catawba drainage (Stuckey 1979), and Hertford, Mcdowell, and Wilkes (Radford et al.l 1968) Counties
• North Dakota: Lake Sakakawea (North Dakota Game and Fish Department 2015), Lower Sheyenne (Stuckey 1979), Painted Woods-Square Butte (Associated Press 2008), and Willow (Jason Lee, ND GFD, pers. comm.) drainages
• Ohio: All drainages (Central Hardwoods Invasive Plant Network 2010; Stuckey 1979)
• Oklahoma: Oklahoma - Blue (McGregor and Barkley 1977), Cache, Illinois, Lake Texoma, Little (Stuckey 1979), Lower Canadian-Deer, and Red-Washita (Nelson and Couch 1985) drainages, and Ottawa County (Correll and Correll 1975)
• Oregon: Oregon - Deschutes, Lower Columbia (iMapInvasives 2012), Klamath, Middle Snake-Boise (Oregon State University 2013), Middle Columbia (Rice 2008), Northern Oregon Coastal (Carr 2009), Southern Oregon Coastal, and Willamette (Stuckey 1979) drainages
• Pennsylvania: All drainages (Pennsylvania Flora Database. 2011; Stuckey 1979)
• Rhode Island: North Smithfield in Blackstone drainage, and Silver Hook in Narragansett drainage (University of Connecticut 2011)
• South Carolina: Cooper River and Goose Creek Reservoir in Cooper drainage (University of Connecticut 2011), and Lake Murray in Saluda drainage (Steve de Kozlowski, SC DNR, pers. comm.)
• South Dakota: Burbank Lake (oxbow of Missouri River) in Lewis and Clark Lake drainage (Stuckey 1979), and Cold Brook Reservoir in Middle Cheyenne-Spring drainage (University of Kansas Biodiversity Institute 2008)
• Tennessee: Lower Cumberland (Chester 1975), Lower Clinch, and Lower Cumberland-Sycamore drainages, and Anderson, Carter, Grundy, Hamilton, Hawkins, Knox, Lake, Marion, Obion, Roane, Stewart, and Sullivan Counties (Stuckey 1979)
• Texas: Austin-Travis Lakes, Bois D'arc-Island (Stuckey 1979), Lower Colorado-Cummins (Utah State University 2007), Lower Frio, Lower Guadalupe (Rhandy Helton, TX PWD, pers. comm.), and San Marcos (Lemke 1989) drainages, and Dallas and Randall Counties (Odgen 1966)
• Utah: Lower Bear-Malad (Utah State University 2007), Lower Weber (Bartodziej and Ludlow 1997), and Provo (New York Botanical Garden 2015) drainages
• Vermont: Black-Ottauquechee (Center for Invasive Species and Ecosystem Health 2015), Lake Champlain (Stuckey 1979), Mettawee River (Dritschilo 2010), West (University of Alabama Biodiversity and Systematics 2007), and Winooski River (University of Connecticut 2011) drainages
• Virginia: Lower James (University of Florida Herbarium 2016), Lower Potomac (Orth et al. 1979), Middle Potomac-Anacostia-Occoquan (Stuckey 1979), and Upper Roanoke (Tarbell and Associates Inc 2007) drainages, and Gloucester, Surry, and Virginia Beach Counties (Harvill et al. 1977)
• Washington: All drainages except Washington Coastal (Falter et al. 1974; McKern 1972; Parsons 1998; Parsons 2005; Rice 2008; Stuckey 1979; University of Washington Burke Museum 2007)
• West Virginia: Greenbrier, Little Kanawha (Stuckey 1979), Upper Ohio-Shade, and Upper Ohio-Wheeling (Robynn Shannon, Fairmont State Univ., pers. comm.) drainages
• Wisconsin: All drainages except Duck-Pensaukee, Lower Fox, and Trempealeau (GLIFWC 2008; Michigan State University 2015; Stuckey 1979;WI DNR 2008; WI DNR 2010)
• Wyoming: Clear, New Fork, Pathfinder-Seminole Reservoirs (Bear 2012), Lower Wind, Upper Belle Fourche (Bear 2013), Shoshone (Bear 2014), and Upper Green-Flaming Gorge Reservoir (Lichvar and Dorn 1982) drainages

Canada: Alta., B.C., Ont., Que., Sask.; No specimens have been seen from New Brunswick, but the species is to be expected there.

Germination of seeds is not well understood, but not considered to be the primary means of reproduction (Catling and Dobson 1985; Godfrey and Wooten 1981; Nichols and Shaw 1986).

Although examination for P. crispus hybridization has been limited, two hybrids exist globally, and one hybrid is known to exist in North America.  The hybrid Potamogeton crispus x P. praelongus (= P. x undulatus Wolfgang ex Schultes & Schultes f.) has been confirmed from a northeastern Indiana lake (Alix and Scribailo 2006).  Potamogeton x cooperi (Fryer) Fryer, a hybrid between P. crispus and P. perfoliatus, was found in Europe (Kaplan and Fehrer 2004). Both P. crispus and P. perfoliatus are found in the Great Lakes, but P. x cooperi has yet to be discovered in North America.

In waters too turbid to support other submersed macrophytes, P. crispus may provide ecosystem benefits for fish and wildlife habitat and a source of macroinvertebrate food organisms.  Several species of dabbling ducks are known to eat P. crispus seeds and turions (Hunt and Lutz 1959).

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Socioeconomic	Beneficial

Large infestations of P. crispus can impede water flow and cause stagnant water conditions (Catling and Dobson 1985; ENSR International 2005; Lui et al. 2010). When dense stands of curlyleaf pondweed die off midsummer, it can have a drastic effect on the water quality. A large amount of phosphorus is released into the water which can lead to eutrophic waters and possible algal blooms (Benson et al. 2004; WI DNR 2012). As the vast quantity of plant matter decomposes, the concentration of oxygen in the water can drop significantly and possibly impact fish (IPANE 2013; Lui et al. 2010).

Potential:
Potamogeton x cooperi is a hybrid between P. crispus and P. perfoliatus, which is also found in the Great Lakes., has been found in Europe (Kaplan and Fehrer 2004).

Potamogeton crispus has a moderate socio-economic impact in the Great Lakes.
Realized:
Surface mats of P. crispus can become a nuisance and inhibit aquatic recreation such as boating, fishing, and swimming  (IL DNR 2009; Jensen 2009). Dense colonies of curlyleaf pondweed can restrict access to docks and fishing areas until July, when the plants dieback (Jensen 2009). Dead mats of P. crispus can pile up along the shoreline; greatly reducing the aesthetic value of waterfront property (WI DNR 2012). Expensive control programs are often needed to reduce the impacts on recreational activities and to maintain waterfront property values (IL DNR 2005). Waterfront property owners in Michigan spend an estimated $20 million annually to control aquatic invasive plants—primarily Eurasian watermilfoil and curlyleaf pondweed (MSGCP 2007).

Dense growth of P. crispus can reduce the flow in irrigation canals (Catling and Dobson 1985; ENSR International 2005).

Decomposing mats of curlyleaf pondweed release phosphorus; which can cause an increase in algal blooms and effect drinking water quality (WI DNR 2012).

Potamogeton crispus has a moderate beneficial effect  in the Great Lakes.
Realized:
Curlyleaf pondweed provides habitat for aquatic life when native plants are not present in the winter and early spring (IL DNR 2005). Populations provide habitat for macroinvertbrates, which are food sources for fish and waterfowl on their northern migration (Catling and Dobson 1985; ENSR International 2005; GLC 2006). Beds of P. crispus also provide spawning substrate and habitat for game fish (GLC 2006; Lembi 2003).

Potential:
Potamogeton crispus is able to remove dibutyl phthalate and phthalic acid esters when grown experimentally in contaminated water (Chi and Cai 2012; Chi and Yang 2012). Experiments conducted in China showed that P. crispus is able of removing nitrogen from eutrophic water and sediment; thus improving the water quality (Ren et al. 2011). Curlyleaf pondweed is able to uptake cerium, cobalt, cesium, and their isotopes; indicating that it could be used to treat low level liquid radioactive waste (Hafez et al. 1992). This species is also able to remove cadmium from water, but at the cost of decreased photosynthesis (Sivaci et al. 2008). Populations of P. crispus have no effect on dissolved oxygen concentrations, slightly increase the pH and reduce the total dissolved solids and the nitrogen concentration; leading to an overall improvement in water quality (Wang et al. 2011).

Aqueous extracts of P. crispus demonstrated antimicrobial activity against 17 different microorganisms including Escherichia coli and Staphylococcus aureus (Fareed et al. 2008).

As of 2011, the Great Lakes Indian Fish & Wildlife Commission lists this species a high priority species and recommends it be controlled within their ceded territories (Falck et al. 2012).

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control
Biological
The herbivorous grass carp, Ctenpharyngodon idella, will provide effective control of P. crispus, but may feed on native plants (CEH 2004). Grass carp is illegal in some Great Lake states (GLIFWC 2006).

Other bottom feeding fish, such as common carp, do not feed on P. crispus, but they create turbid water conditions and may prevent the growth of this plant species (CEH 2004).

Physical
Small infestations can be removed manually by cutting, raking, or digging up plants (The Idaho Invasive Species Council Technical Committee 2007). The optimal timing for cutting is debated. Some agencies claim that plants should be cut  im early spring and as close to the sediment surface as possible to prevent turion formation (MI DEQ 2015; WI DNR 2012). Other organizations claim that cutting should not be carried out until mid-to later summer to prevent regrowth (CEH 2004). Regardless when cutting/raking occurs, it is important to remove as many plant fragments as possible to limit new populations of curlyleaf pondweed

When removing this species via digging, root crowns should also be removed from the soil; this removal method can be enhanced by the use of a suction apparatus (ENSR International 2005).

The use of equipment such as dredges, underwater rototillers, or hydrorakes are more effective for populations in deep waters (ENSR International 2005; USACE 2011). These physical methods are indiscriminate and should only be used on monoculture populations of P. crispus (ENSR International 2005). Plant material should be removed after it is cut to prevent regrowth or decreases in oxygen concentration due to plant decomposition (ENSR International 2005).

Another option would be to use blankets or other benthic barriers to block sunlight from reaching P. crispus (ENSR International 2005). This method will eliminate all vegetation, including native species, in 30 – 60 days (ENSR International 2005; GLIFWC 2006).

In some waterbodies, water draw-down may be an option. All plants, including natives, will be exposed to drying or freezing (ENSR International 2005). A water draw-down in autumn may kill P. crispus turions and increase the efficacy of this control method (MI DEQ 2015).

Chemical
Potamogeton crispus plants dieback completely in early summer; in order for effective control, herbicides should be applied before dieback occurs (MI DEQ 2015).

Potamogeton crispus was effectively controlled by fluridone in test site lakes in Michigan (Getsinger et al. 2001). Control can be obtained with a dose of 6 - 15 ppb with an exposure time of 60 – 120 day (ENSR International 2005). This method is only appropriate for whole lake applications (IL DNR 2005).

Endothall and diquat may offer effective control if applied to P. crispus before turion production; typically in April and May (ENSR International 2005; WI DNR 2012). Plants may still continue to grow, but their reproductive ability will be greatly reduced (ENSR International 2005). Application of either of these chemicals is most effective when the water temperature is between 50o – 55o F (IL DNR 2005). Reapplication of diqaut in subsequent years may be necessary for complete control  (Bugbee 2009).

Herbicides containing 2,4-D will be rapidly taken up by P. crispus, but complete control is unlikely (ENSR International 2005).

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