Invasive species are non-native plants or animals that disturb the habitat of native species, forcing them to decline in population or to disappear altogether. Invasive are either introduced accidentally or intentionally by humans or their activities. They are always considered to be pests and harmful to the ecosystem in some way. Pest control costs and environmental damages can add up to millions of dollars per year.
What can you do?
Some of the most important things you can do to prevent the introduction and spread of invasive species is to keep your outdoor recreation gear clean and not landscape with invasive plants. Educate yourself and others about problem platens and animals. The UW-Extension, Wisconsin DNR, and Wood County Master Gardeners have educational materials specific to Central Wisconsin. Eradicate plants growing on your land or volunteer to help remove invasive plants from natural areas.
Common Buckthorn (Rhamnus cathartica)
And Glossy Buckthorn (Rhamnus frangula)
Buckthorn was imported from Europe in the 1800’s for shelter belts and ornamental use. The shrub can become dominant in wooded areas and is now illegal to sell in some states. Buckthorn lowers the forage diversity of the forest, and Common Buckthorn is thorny whichmakes walking through these areas difficult.
Looks like a shrub or small tree and can reachup to 22ft. The 10 in. wide trunk has gray and
brown bark with a rough texture. Inner bark isyellow. Twigs often tipped with a thorn. Leaves
are glossy green,broadly oval, with jaggedtoothed margins, and 3-4 pairs of up curved veins.
It flowers May through June with clusters of 2 to 6 yellow-green flowers coming from stems near the
base of the leaf stalks. These stalks contain smallblack fruit which ripens August – September.
Reproduction is by seed and is scattered by birds.
Glossy Buckthorn is similar to Common Buckthorn except it is thorn less; leaves are not toothed; and the underside of the leaf is hairy.
Prescribed burns in early spring are useful in killing seedlings, otherwise hand pulling is the most effective way of removal.
Reed Canary Grass
Reed Canary Grass (Phalaris arundinacea)
Native to temperate regions of US, Europe, Asia. Eurasian variety is considered more aggressive. Introduced for forage and hay into the Northwest. Presently used in Europe for biomass fuel.
Grows 2 – 9 feet tall. Green leaves are up to 10 in. long and ¾ in. wide. Hairless. Base of each leaf is wider than the stalk. Seed head initially green, then golden tan, and then later light tan. ReproducesThrough seeds and underground stems.
Mechanical Control: Mowing twice yearly before seed matures. Small discreet patches may be covered by black plastic for at least one growing season. The bare spot can then be reseeded with native species.
Chemical Control: Small, scattered clones can be controlled by tying the stems together, cut down, them apply glyphosate at 33% active ingredient.
Purple Loosestrife (Lythrum salicaria)
Purple Loosestrife is native to Europe, Asia, and northwest Africa. It became established in the estuaries of Northeastern United States in the 1800’s. In 1996,the plant was found in all of Canada and theU.S., except Florida. Loosestrife is illegal to sell in the United States.Purple Loosestrife grows along streams or in marshy areas. It spreads rapidly and quickly degrades wetlands and farm fields by choking out other plants needed by wildlife.
Stems are square and slightly hairy, leaves lanceshaped and opposite. It can grow 4-10 ft tall with
long spikes of purple flowers. One plantcan have30-50 stems from one rootstock. Tiny seeds
develop in capsules less than 1” long. One plantcan produce up to 2.7 million seedseach year.
Seeds are dispersed in water and mud via animalsand people.
Small infestations can be controlled by removal of plant, roots, and underground stems.
Chemical Control: Herbicides can be applied to individual plants.
Galerucella pusilla -- a leaf-feeding beetle. An MHS Science Class is breeding these beetles for control of these plants in MOLS.
Galerucella calmariensis -- a leaf-feeding beetle
Hylobius transversovittatus -- a root-mining weevil
Common St. John’s Wort (Hypericum perforatum)
The Common St. John’s Wort is native to Europe, North Africa, and Asia. It was brought to the US in the 1700’s as an ornamental. The plant crowds out native species, invades healthy rangelands, and is poisonous to livestock. It is photochemical and can cause chemical blisters on animals and people. Gloves should always be worn when handling the plant.
Stems grow 1-2.4 feet in height, are reddish, smooth and somewhat two-edged, woody atthe base, and branch out towards the top of the plant. Leaves are 1-2 inches long, narrow lance shaped, and spotted. The 5 petalFlowers are yellow with small black dots in the center. The spring to summerflowers occur in clustersat the ends of stems with 25-100 flowers percluster. The red berry is split into 3 sections with Numerous dark brown seeds. One plant canproduce up to 100,000 seeds per year.
Mechanical Control: Pull the entire plant out of the ground. Repeated pulls are recommended.
Chemical Control: Several herbicides are effective. Repeated sprays are recommended.
White Poplar (Populus alba)
Introduced to North America by early settler. Has an extensive root system that is tolerant to lots of water and salt. Reproduces rapidly. Used for landscaping and parks. Some states have banned the sale of this plant.
Medium to tall tree that sometimes gets confused with maple because the leaves are shaped similar
to a maple-leaf. The top of the leaf is green, with the underside whitish. The trunk has black diamond
shapes engraved on it.
Mechanical Control: Cut down close to the root system.
Chemical Control: several herbicides are effective after repeated use.