Aquatic plant communities perform valuable services, including stabilizing sediment, improving water quality, and providing support for fish and other animals. However, these functions can be disrupted by invasive aquatic plant species such as curly-leaf pondweed (Potamogeton crispus). Curly-leaf pondweed inhibits the growth of native species and interferes with recreational activities.
Research at MAISRC has determined that low-dose, early season endothall herbicide treatments can successfully control curly-leaf pondweed. Current research includes analyzing data to determine how many herbicide treatments are needed for control and post-treatment monitoring and transplanting native plants to treated areas. Click here to download a factsheet about curly-leaf pondweed.
About curly-leaf pondweed
What it is
Curly-leaf pondweed is a non-native, invasive aquatic plant that can grow in very dense stands, displacing native species. One of its advantages is that it produces hardy turions – buds that can remain viable for long periods before sprouting to form new plants. Curly-leaf pondweed can grow in depths up to 15 feet.
Curly-leaf pondweed is generally the first pondweed to come up in spring, helping distinguish it from other native pondweeds. It dies in the mid-summer, and dead plants may accumulate on shorelines. Its primary means of reproduction is through the production of turions, hundreds of which can be produced by each plant. Turions remain dormant in the sediment through the summer and germinate in the fall. Germination rates can be as high as 80 percent, and turions can remain viable in the sediment for two or more years.
What it affects
Curly-leaf pondweed displaces native plants, disrupting vegetation structure that provides forage and shelter for waterfowl, fish, invertebrates, and algae-consuming zooplankton. It also reduces recreational opportunities for swimmers and boaters by forming thick surface mats.
Where it’s found
Curly-leaf pondweed occurs in over 750 water bodies in Minnesota, spread throughout 70 out of the state’s 87 counties. It is native to Eurasia, Africa, and Australia, but is now found throughout much of the United States.
How it spreads
Curly-leaf pondweed is spread by humans inadvertently transporting plants and/or fragments among waterbodies. Infestations often occur in high-use lakes.
What it looks like
Curly-leaf pondweed produces a long stem (up to a meter) with small, submerged leaves that have distinct “teeth,” or wavy edges. In the spring, its turions look like small greenish-brown pinecones.
Curly-leaf pondweed research at MAISRC
- Conducted research on Lakes Riley and Susan (with Mitchell Lake as a reference lake) that showed that low-dose, early season endothall herbicide treatments successfully controlled curly-leaf pondweed within treatment years without adverse impacts on native plant communities. Curly-leaf pondweed frequency of occurrence, biomass, and turion production all declined by 90% or more in treated lakes.
- Developing citizen-science monitoring programs to support detection of new infestations and track outcomes of control and restoration efforts
- Analyzing data collected over the last 10-15 years by the Minnesota DNR, the University of Minnesota, watershed districts, and others on the response of curlyleaf pondweed and other native plants to management. This will help answer how many subsequent herbicide treatments are needed for effective control, what time of year and/or how broadly applied the treatments should be to produce the best results, how environmental conditions influence curlyleaf abundance, and how native plants respond to these herbicide treatments.
- Following up on previous endothall herbicide treatment research to determine how to best enhance the response of native plants, particularly in lakes with poor water clarity. This is being addressed through post-treatment monitoring, assessment of alum treatments, and transplanting native plants to treated areas. The ultimate goal of this work is to reduce invasive aquatic vegetation and support diverse aquatic plant communities that provide important ecological functions.
- Developing and evaluating new techniques to selectively control invasive plants
- Restoration and maintenance of native macrophytes in lakes – partnership with Riley Purgatory Bluff Creek Watershed
- James A. Johnson , Ajay R. Jones & Raymond M. Newman (2012): Evaluation of lakewide, early season herbicide treatments for controlling invasive curlyleaf pondweed (Potamogeton crispus) in Minnesota lakes, Lake and Reservoir Management, 28:4, 346-363
- Ajay R. Jones , James A. Johnson & Raymond M. Newman (2012): Effects of repeated, early season, herbicide treatments of curlyleaf pondweed on native macrophyte assemblages in Minnesota lakes, Lake and Reservoir Management, 28:4, 364-374
- Factors affecting the abundance and control of curlyleaf pondweed in managed and unmanaged systems: analysis of results from 60 lakes (Final report)
- New suite of research on aquatic invasive plants kicks off (MAISRC Newsletter)
- MAISRC researchers examining effects of alum treatments on curly-leaf pondweed and native plants (MAISRC Newsletter)
- MAISRC graduate student thesis examines effect of herbicides on curlyleaf pondweed and native plants (MAISRC Newsletter)
- Control of Curlyleaf Pondweed (Potamogeton crispus) with Endothall Herbicide Treatments and the Response of the Native Plant Community in Suburban Lakes (Graduate student thesis)
- U of M Adding Research Capacity in Aquatic Invasive Plants Management (Press Release)
- Two Invasive Plant Projects Launched (MAISRC Newsletter)