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Invasive Species
Since the 1800s over 160 non-indigenous aquatic species have become established in the United States including 24
species of fish,9 mollusks, and sixty-one plant species.
The following are common in the Lake Mitchell area.
Eurasian Water Milfoil - This plant has feathery green leaves and grows in thick clumps. In Lake
Mitchell it is widely found in depths up to ten feet.
It has been identified in nearly 500 Michigan lakes and was first discovered in Lake Mitchell in the late 1980s. It
thrives in nutrient rich lakes receiving nitrogen and phosphorus-laden runoff. Unlike many plants, Eurasian Water
Milfoil does not rely on seed for reproduction. It reproduces by fragmentation which allows it to disperse over
great distances. For this reason, harvesting living milfoil is counter productive.
There are two category of herbicides; Contact and Systemic. Systemic herbicides kill the entire plant and contact
herbicides kill only the shoot portion of the plant. Systemic herbicides, 2-4-D and Triclopyr (Renovate), are used
in Lake Mitchell to control of Eurasian Watermilfoil. Reward (Diquat Dibromide) a contact herbicide, is used in the
coves and near shore areas because 2-4-D can not be sued within 250 feet of shallow wells.
Purple Loosestrife -Purple loosestrife is an erect perennial herb with a square, woody stem that
grows from four to ten feet high, depending upon conditions, and produces a showy display of magenta-colored flower
spikes throughout much of the summer. Mature plants can have from 30 to 50 stems arising from a single rootstock.
Purple loosestrife is a dominant plant in North Franke and Big Coves. It outcompetes and replaces natives grasses
such as cattails which provide a higher quality of nutrition for wildlife. Purple loosestife occurs in every state
but Florida.
Purple loosestrife is an ornamental plant and my unknowingly be growing in gardens along the Lake Mitchell
shoreline. It is illegal to sell or distribute this plant in Michigan. Small infestations of young purple
loosestrife plants may be pulled by hand, preferably before seed set. For older plants, spot treating with a
glyphosate type herbicide (e.g., Rodeo® for wetlands, Roundup® for uplands) is recommended. These herbicides may be
most effective when applied late in the season when plant are preparing for dormancy. However, it may be best to do
a mid-summer and a late season treatment, to reduce the amount of seed produced.
While herbicides and hand removal may be useful for controlling individual plants or small populations, biological
control is seen as the most likely candidate for effective long term control of large infestations of purple
loosestrife. The Lake Mitchell Improvement Board hopes to introduce galerucella plant-eating beetles into Big Cove
this summer.
Phragmites - Phragmites, also known as the common reed, is a perennial wetland grass that can grow
to 15 feet in height. Found in every state in the United States, this plant threatens the ecological health of
wetlands by crowding out native plants and animals. A small patch of phramites was found in Big Cove near the Camp
Torenta Canal and chemically destroyed last summer. This plant has been seen as part residential landscape projects
on Lake Mitchell. Although there are native forms which pose no threat, the invasive phragmites plant should be
removed before it can spread to our wetlands.
Zebra Mussels - In September a colony of zebra mussels was found on the bottom of a boat in Lake
Cadillac. With their zebra-like striped shell and triangular shape, zebra mussels are easy to identify. Most are
smaller than a pistachio nut and will be found attached to hard surfaces like boat bottoms, dock posts, rocks, and
woody debris. If stepped on they can cut one's foot. In lakes heavily infested with these mussels, water clarity
may improve dramatically. With deeper light penetration, plants may sprout in greater depths. Zebra mussels feed by
filtering from the water tiny algae which is a a vital part of the lake's food chain. This can effect the amount of
food for larval fish. There is no known method for controlling zebra mussels. Zebra mussels are found in many of
Michigan's lakes.
What you can do to keep Invasive species out of Lake Mitchell
INSPECT your boat and your equipment and remove all weeds from your trailer propeller, anchor, and any other place
found on your boat.
DRAIN all water from the boat motor, bilge, live well, and bait buckets on dry ground.
DISPOSE of leftover bait in a trash receptacle, not in the water.
RINSE your boat and all fishing equipment with hot tap water, OR thoroughly dry your boat outdoors for at least
five days before traveling to a new lake or stream.
TEACH and help others to do the same.
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