Curled Pondweed

Native:

 

 

Large-leaved Pondweed (Potamogeton amplifolius) has leaves with smooth edges.

Curled Pondweed is native to Eurasia, Africa, and Australia. It was first introduced to the US in the mid-1800s through fish stocking operations, likely by accident.

It is generally found in ponds, rivers, lakes, wetlands, streams, and brackish waters. Curled Pondweed prefers alkaline and eutrophic waters, and can be found in disturbed sites and polluted waters. It grows in waters 1 – 3 m deep in a range of sedimentary conditions, like gravel, fine sand, loamy mud, and clay.

Curled Pondweed reproduces mainly vegetatively, via rhizomatic spread. However, vegetative reproduction is also accomplished by plant fragments that can form whole new plants, as well as turions, which are bur-like, prickly buds that form along the stem at or near peak biomass. Turions are dispersed by water flow and can stay viable for up to 2 years. They eventually sink to the bottom of the waterbody and germinate the following year. Curled Pondweed can also reproduce by seed, but it has a very low germination rate.

Curled Pondweed fragments and turions are transported by boats and other pieces of aquatic equipment. Turions are also dispersed by wind and water flow. Waterfowl can spread the plant great distances along their migratory routes. Curled Pondweed is also spread by humans, as it is often accidentally included in aquaculture mailings.

Curled Pondweed is currently found in Whistler, but not Squamish or Pemberton, so the best approach to controlling its spread is by PREVENTION.

 

Learn to identify Curled Pondweed: use the images presented in this profile page to learn how to identify Curled Pondweed.

What to do if you spot it: You can report any Curled Pondweed sighting by clicking here.

 

DO:

• Ensure that plants are disposed of in a garbage bag if found in floral arrangements to prevent seeds from spreading.
• Clean, Drain, and Dry all watercraft. Rinse all mud, debris, and plant fragments from all equipment, wading gear, and boats.

 

DO NOT:

• Do not plant Curled Pondweed in a water garden.
• Do not dispose of aquarium plants into water bodies.

Control

Cultural

Benthic barriers made from a variety of materials can be placed over an infestation to prevent sunlight from reaching the plants and restrict upward growth. Installation should occur during spring to prevent the plants from exceeding 0.5 m tall and greatly increasing their biomass.

However, keep in mind that benthic barriers affect all vegetation, not just the undesirable Curled Pondweed.

Mechanical

Raking and hand-cutting Curled Pondweed is a relatively effective method of mechanical control but should be performed early in the season. Ensure that as many plant fragments are removed as possible, as any left could produce new plants. Cutting at the sediment surface has been shown to reduce turion production.

Mechanical methods generally need to be repeated for several years, and monitored thereafter to ensure the plant doesn’t re-establish.

Chemical

Herbicides cannot be applied in aquatic environments in Canada. Herbicide control is not recommended for this species.

Biological

Sterile triploids of the White Amur Grass Carp (Ctenopharyngodon idella) can be used to control Curled Pondweed infestations, as they are a relatively non-selective herbivorous species. Careful monitoring of feeding impacts is necessary, as the fish might also consume desirable aquatic vegetation.