TO: PLC Members
FROM: David P. Pearson
DATE: July 12, 2019
RE: Curly-leaf pondweed in Pickerel Lake
Dear PLC Members and Friends of Pickerel Lake,
I have some bad and disturbing news about the first invasive species identified in Pickerel Lake. Dennis Skadsen, who advises the PLC Board on water quality and environmental issues, recently identified curly-leaf pondweed in Pickerel Lake near the boat launch in the west state park. At this point, curly-leaf pondweed has been identified only in that small area of the lake. We think it is important to inform you about this development, to explain what curly-leaf pondweed is, why it is a problem, and to discuss plans to address the problem.
Curly-leaf pondweed: What it is and why it is a problem
Curly-leaf pondweed is an invasive aquatic plant that has been found in many Minnesota lakes and is spreading in South Dakota. It is established in Roy Lake and Big Stone Lake.
Like many invasive species, curly-leaf is spread from one body of water to another by the unintentional transfer of plant fragments on trailered boats. In all likelihood, visitors to Pickerel Lake had curly-leaf pondweed fragments on their boat, failed to inspect and clean the boat, and thus plant fragments were deposited in Pickerel Lake.
Curly-leaf is one of the first aquatic plants to emerge in the spring. It grows rapidly in early spring, and then the plant usually dies by midsummer. It is identified by leaves that have undulating and finely serrated ridges.
Curly-leaf is a problem because its rapid growth produces extensive, dense mats of vegetation in water three to ten feet deep. In addition to displacing native aquatic plants, the heavy, dense weed mats can make boat traffic difficult or impossible. In midsummer, curly-leaf plants usually die. As the large mass of dead plant material decomposes, it depletes oxygen and adds phosphorous. The extra phosphorous generated by the decomposition process adds to existing phosphorous problems. This can worsen late summer algae blooms. In addition, the dead plant material eventually washes onto the lakeshore which is a nuisance and requires removal.
Some literature suggests that curly-leaf is good for pan fish and leads to improved blue gill and perch fishing by creating cover for small fish.
What can be done to address this problem?
The PLC Board is investigating this problem. We are doing our own research, and we are in contact with South Dakota Game, Fish and Parks to get their input and assistance in developing a response plan. We are also in touch with SDSU and people in Minnesota who have experience with this problem. We currently understand that curly-leaf can be managed by mechanical harvesting and removal of the plants or by treatment with herbicides or a combination of these methods. We are investigating all options and are in communication with other lakes to obtain information regarding the best way to address this new challenge.
Elimination may not be realistic and may be very expensive, at least once it gets established in the lake. To the extent mechanical removal of curly-leaf pondweed becomes a necessary option, we will all have to consider how to pay for it. The same is true for the application of herbicides.
We will be posting information about curly-leaf on the
PLC website. F
or information about PLC’s work on curly-leaf and other invasive species
click here
. State-wide information about curly leaf pondweed
and pictures of curly-leaf so you can identify it
can be found
here
. Your help in identifying curly-leaf is important so we can determine where it is in the lake and how to attack it. The plant is largely dormant now, but may emerge next spring, and we need to know where it is. If you identify what you think is curly-leaf, please notify the PLC right away by emailing
AIS@pickerellakeconservancy.org
. We want to monitor the location and spread of curly-leaf in Pickerel Lake.
We will keep you informed about plans to address curly-leaf pondweed, and we would appreciate your input about how to eliminate, slow down or deal with this problem. This will be an important topic at the PLC annual meeting which will be held at the Pickerel Lake Bible Camp on August 10, 2019 at 10 am.
Thank you.
David P. Pearson
PLC President
1841 Dulynn Road
Grenville, SD 57239
