Curly leaf Pondweed (CLP)

Potomogeton crispus

By: Chris Hamerla

Curly-leaf Pondweed (CLP)

What is CLP:

Curly-leaf pondweed (CLP) is a non-native submerged plant that grows well in cool water.  It was originally found in Europe, Asia, Africa, and Australia. CLP was accidentally brought into the United States when the common carp was introduced during the 1800’s.

CLP has very distinguishable leaves that look similar to lasagna noodles. The tip of the leaf is rounded and the edges are serrated (fine-toothed). Native plants such as white stem pondweed and clasping leaf pondweed are sometimes mistaken for CLP.

Another distinguishing feature of CLP is its extremely early growth. While other plants are dormant under the ice, CLP can start growing.  As the ice melts in spring CLP is among the first plants to show up and has a head start on native species.  This head start allows CLP to out compete native plants for nutrients, space, and sunlight. However, as fast as CLP grows during the spring, it is first to die off.

Waters will vary but normally by early to mid July CLP has disappeared from weed beds.  Before the plant dies turions are formed. Turions are buds that later become the growth of a new plant. These turions settle to the bottom and lay dormant. When water temperatures cool in fall many of the turions begin to grow.  Some of the turions can lay dormant for years. Depending on ice and snow conditions CLP will continue to grow under the ice or may stop till conditions are right the following spring.

Parts of the plant that get broken off are also able to continue growing. As with other aquatic plants, care should be taken to clean all plant material from your equipment before leaving the body of water. Anchors should also be washed off since seeds and turions can be transferred in the mud. These actions will contain the possible spread of this and other invasive species.

Why is Curly leaf pondweed Harmful:

The negative effects of this invasive specie are related to both its early growth and die off during the year.  The early growth and maturity of CLP blocks sunlight from native plants.  The early die off leaves mats of CLP decomposing on the surface of the lake.  As the plants breakdown they add phosphorus and other nutrients into the water.  These added nutrients increase the amount or potential for algal blooms.

How to Control CLP:

Since CLP grows so early in the season it is easy to identify areas of infestation. If a single or few plants are found early enough control methods can be as simple as hand pulling. Like Eurasian water milfoil, a common area CLP will get its start is near a boat landing. Fragments of plants are brought in because they were attached to a boat or trailer that was launched at the landing.

Since the area around the landing may have little or no vegetation the CLP doesn’t have competition from other vegetation and grows easily. Herbicidal treatments are needed once CLP has become established.  Contact and permits from the DNR are required for chemical treatments. Typically a lake management plan, including mapping of CLP and a lake survey of the aquatic plant life, needs to be completed before treatment starts.

Chris Hamerla is the Aquatic Invasive Species Coordinator of Lumberjack Resource, Conservation, & Development Council serving Lincoln, Langlade, and Forest Counties in northern Wisconsin. As the Aquatic Invasive Species Coordinator, Chris focuses on implementing AIS prevention and control efforts through public awareness and education programs. For more information or have any questions contact Chris at 715-362-3690 e-mail chris_h@frontier.com

Learn more about each Aquatic Invasive Species (AIS) Click on the Links Below:

Eurasian Watermilfoil
Rusty Crayfish
Asian Carp
VHS (Viral Hemorrhagic Septicemia)