Uprooting invasive knapweed

By Kary Askew Garcia, MNA Intern

A moth rests atop a knapweed flower. Photo courtesy of MNA archives.

A moth rests atop a knapweed flower. Photo courtesy of MNA archives

MNA is hosting several stewardship events this summer to remove the invasive knapweed plant from various sanctuaries.

The invasion of knapweed poses a danger to native plant life and must be uprooted. The knapweed’s origins are traced back to southeastern Europe. The plant begins to grow as a rosette of leaves in its first year of life and then later on grows a flower stalk ranging from six to 36 inches in height. The flower is usually pink or purple in color with a spotted head underneath, as knapweed is also referred to as “spotted knapweed.”

Knapweed can be found in well-drained soils, dry prairies and dunes. Knapweed is especially harmful to oak barrens, which are endangered worldwide.

The weed’s invasion has caused a decline in native plant species, which is threatening to the ecosystem. It can also alter water quality by causing an increase in soil runoff and erosion.

Spotted knapweed growing on dry terrain. MNA archives.

Spotted knapweed growing on dry terrain. Photo courtesy of MNA archives

Two common ways of eliminating knapweed are simply pulling the plants or mowing them down. There are also herbicides and chemicals that can also be used for removal but have several regulations and must be used carefully as to not upset any other plant or wildlife.

Two different insects have also been introduced to inhibit the knapweed from spreading seeds: flower weevils and seedhead flies. These insects introduced to the knapweed are a form of biological control of the invasive species.

Of these methods, MNA has most commonly uprooted the weed. Uprooting sounds much easier than it is, involving tools to help pull as many of the knapweed’s roots out of the soil as possible. If left behind, the roots could help the weed grow again and damage native plant life.

The knapweed has a tendency to knock out all other vegetation surrounding it, making many ecosystems bare if it isn’t removed.

MNA has also used prescribed burns and herbicide to remove larger amounts of knapweed in sanctuaries. Simply pulling knapweed when it is extremely abundant wouldn’t prove effective; burns and chemicals have helped to reduce the occurrence of the plant.

For more information on spotted knapweed, see Michigan State University’s Agriculture and Natural Resources website here.

Volunteers and stewards help pick knapweed at an MNA nature sanctuary. Photo courtesy of MNA archives

Volunteers and stewards help pick knapweed at an MNA nature sanctuary. Photo courtesy of MNA archives

MNA is calling for volunteers to help pull spotted knapweed from different sanctuaries. The next pull will be hosted at the Calla Burr Nature Sanctuary in Oakland County on July 10 from 9 a.m. to 1 p.m.

More upcoming knapweed removal events:

  •  July 22: Volunteer Day: Lefglen Nature Sanctuary in Jackson County. 9 a.m. – 1 p.m.
  • July 25: Spotted Knapweed Pull at Calla Burr in Oakland County. Begins 9 a.m.
  • July 26: Spotted Knapweed Pull at Keweenaw Shores II Plant Preserve in Keweenaw County with Nancy Leonard. Begins 11 a.m.
  • August 9: Hike & Volunteer day: Redwyn’s Dunes in Keweenaw County. Begins 11 a.m.

Please contact the MNA office for more information about volunteering and preserving Michigan’s nature.

Advertisements