In late summer 2019, fragments of curly-leaf pond weed (“CLPW”) were first identified in the northwest portion of Pickerel Lake. The PLC sounded the alarm on this issue and is leading the fight to combat CLPW. We are providing information about CLPW, why it is a problem, and the PLC’s plans to combat CLPW at Pickerel.
1. Why CLPW is a problem.
CLPW is an invasive aquatic plant that has been found in many lakes in the United States. Like many invasive species, CLPW is spread from one body of water to another by an unintentional transfer of plant fragments on boat trailers.
CLPW is an aggressive, fast growing aquatic plant with unique characteristics which make it difficult to combat and eradicate. Unlike native aquatic vegetation which remains dormant over the winter, CLPW starts to grow during the winter months when the lake is covered with ice and snow, and even in the absence of much sunlight. CLPW grows very rapidly in early spring as soon as the ice is out. It is therefore way ahead of native aquatic plants in terms of spring growth and propagation.
CLPW usually reaches its maximum height and growth stage in late May and early June. At that point, it reaches the lake surface. Generally, CLPW grows in water 15 feet deep or less. The plants produce what are called “turions,” analogous to pine cones, which are produced when the plant reaches maximum height in late spring/early summer. CLPW propagates by dropping the turions on to the lake bottom, and the turions then sprout in the next fall or winter.
CLPW forms heavy, dense, weed mats that can be 3 to 10 feet deep. These dense mats of vegetation can make boat traffic difficult or impossible, and also prevent swimming and other lake activities. Because of the dense nature of CLPW, it displaces native aquatic plants.
By mid-summer, CLPW plants usually die. As the large mass of dead plant material decomposes, it depletes oxygen and adds phosphorus to the water. The extra phosphorus generated by the decomposition process adds to the existing phosphorus problems in freshwater lakes. This creates an additional problem by worsening late summer algae blooms. In addition, the dead plant material eventually washes onto lakeshore beaches where it is a nuisance and must be removed.
2. PLC’s plan to combat CLPW.
PLC has retained PLM Lake & Land Management Corp. to develop and implement a plan to combat CLPW at Pickerel. PLM has over 15 years of experience in working with lake associations, state agencies, municipalities, watershed districts and others in combating and managing various aquatic invasive species, including CLPW. PLM is very well qualified and is highly recommended. SDGFP reviewed the PLM proposal and supports our plan to use PLM to combat CLPW. (But GF&P has no money to help in this effort.)
In Spring 2020, PLM will conduct what it refers to as a “delineation survey” of Pickerel. This survey involves traversing the entire shoreline of the lake by boat in depths 15 feet and less to visually identify CLPW. CLPW is easy to identify in late spring because it is the only aquatic vegetation visible at the surface of the lake. In locations where CLPW is identified, PLM will conduct a more detailed survey to determine the scope of the infestation.
Based on the survey, PLM will prepare a written plan with recommendations on how to combat and control CLPW in Pickerel now and in the future. At this point we do not know the extent of the infestation. Typically, CLPW is controlled by the application of an herbicide. There are several different herbicides that can be used. Some of these have an adverse effect on native vegetation. Therefore, in late summer 2020, PLM will conduct a follow up survey of vegetation in the lake to catalog the types of native vegetation present. This will enable PLM to select the appropriate herbicide to combat CLPW while having the least impact on native plant species in the lake.
Depending on the scope of the infestation, we can expect that PLM will recommend the application of an herbicide in the spring of 2021. PLM will probably recommend an additional survey of the lake in the spring of 2021 to identify once again the location of CLPW infestations. PLM uses a sophisticated technology to properly apply the herbicide and to incorporate variables such as water depth, water flow, wave action, etc. The herbicides are quite effective, but must be properly and carefully applied in order to have optimum impact.
If we are lucky, the infestation will be small, and we may be able to eradicate CLPW. PLM has had significant successes in controlling CLPW. However, once established, CLPW is notoriously difficult to eliminate and, if there is an infestation, the effort to control CLPW could take years. We expect to have an ongoing relationship with PLM as we continue our efforts to combat CLPW in the years ahead. We will keep you informed about the battle to combat CLPW.
3. What you can do.
We need your help in this process. First, we need your help in identifying CLPW plants in the lake. CLPW grows in water 15 feet deep or less. It may be growing adjacent to your dock or boat lift. We are enclosing pictures of CLPW plants. If you see a plant that looks like CLPW, please take a picture and a sample and report your findings to the PLC at ais@pickerellakeconservancy.org so we can determine whether or not it is CLPW. Identification can sometimes be tricky because CLPW closely resembles a native plant. If you do identify what you think is CLPW, mark the location carefully so we can do further investigation of that area.
Combating CLPW is a long-term and expensive battle. Please contribute to the PLC. The PLC is working to protect the lake, your enjoyment of the lake and your property values. So please become a member and help us fight CLPW and other aquatic invasive species.
Thank you.
Pickerel Lake Conservancy