Curlyleaf Pondweed
A Serious Threat to Lake Hubert

What is it?
Curlyleaf Pondweed, (Potamogeton Crispus) is an introduced species of underwater plant that can grow into thick surface mats.  Although it looks similar to native species of Pondweed such as White Stemmed Pondweed and Big Leaf Pondweed, it is very different in its growth habit.

What does it look like?
Unfortunately, Curlyleaf Pondweed looks a lot like native pondweeds which are commonly called "cabbage" by fishermen. If you have a piece of Pondweed in your hand, it is likely to be Curlyleaf if ALL of the following are true.

- It has "wavy" or "curly" leaves.
- It has a plastic-like feel.
- It has serrated (tiny saw tooth) leaf edges.
- It has alternate leaves on the stems (the leaves do not occur at the same point on opposite sides of the stem)
- It has reddish stems.

        
An approximately 6 inch long sample of Curlyleaf Pondweed

Where did it come from?
It came to Minnesota in the early nineteen hundreds along with Carp from the Orient. It is now in most Minnesota lakes and left unchecked it can seriously degrade the quality of a lake for recreation.

When is it most visible in the lake?
Curlyleaf Pondweed grows beneath the ice when there is little snow cover to block sunlight. In spring the Curlyleaf grows rampantly and soon forms the dense surface mats that cause problems. In summer, the Curlyleaf produces seed like structures called turions which float to other locations on the lake and then sink to the bottom where they germinate, thus spreading the unwanted plants. After dropping their turions, the plants die back and seem to disappear, only to begin growing again in the late fall and early winter. Curlyleaf Pondweed can also be spread from pieces of stems and leaves that have floated around the lake.

Why is it a serious threat?
Curlyleaf Pondweed can grow into surface mats so thick that boats and swimmers cannot get through it. It crowds out native underwater plants and can be detrimental to fish populations.


What uncontrolled Curlyleaf Pondweed can do in a lake.

What is being done to combat Curlyleaf Pondweed in Lake Hubert?

There is no known way to eliminate Curlyleaf Pondweed once it is in a lake but it can be controlled.

Special chemical herbicides approved by the State of Minnesota and applied by licensed companies can control Curlyleaf when applied correctly and at the proper time of the year. The Lake Hubert Conservation Association contracted for and paid for spraying of a large patch of Curlyleaf in the northeast corner of the lake in 2003. This spraying, along with plenty of snow on top of the ice (which reduces or eliminates the light getting through the ice to the underwater plants) reduced the Curlyleaf Pondweed population to the point where we do not have to spray again in the spring of 2004.

We will continue to monitor the Curlyleaf Pondweed and will take appropriate measures when needed.

What can individual property owners do?

The association is not allowed to treat Curlyleaf Pondweed close to privately owned shoreline. If there is a large concentration of Curlyleaf Pondweed growing on the lake bottom directly out from your property and within 150 feet of your shore, you can apply to the DNR for a permit for spraying and contract with a professional spraying company to treat the Curlyleaf.

If you find large patches (hundreds of plants) of Curlyleaf Pondweed growing in the lake, note the exact location and let the association know where you found it. (GPS coordinates would be wonderful if you can provide them). You can e-mail your findings to us at  LakeHubert@aol.com
 or drop us a note at LHCA, P.O. Box 1352, Lake Hubert, MN 56459.

Links to additional Curlyleaf Pondweed information.

Minnesota DNR Curlyleaf Web Page

Minnesota Lakes Association Curlyleaf Web Page