July weed of the month: Cutleaf teasel
By Emilie Justen, Minnesota Department of Agriculture
July's Weed of the Month, cutleaf teasel (Dipsacus lacinatus), once had a useful propose. But now the weed is being targeted for eradication in Minnesota.
Cutleaf teasel is an herbaceous perennial plant that dies after producing seed. It was brought to North America from Europe in the 1700s and its stiff, bristly seed heads were used in the textile industry to raise the nap on fabric. Cutleaf teasel has also been used as an ornamental plant in gardens and flower arrangements.
Despite its uses in the textile and floral industries, cutleaf teasel has become invasive in Minnesota and is a noxious weed on the eradicate list. It produces a large amount of seed that can stay viable in the soil for several years. Most of the seed falls near the parent plant, and when the seed germinates it forms dense monocultures that choke out other plants. The seed can be spread by water and has been found growing along creek banks in southeastern Minnesota.
Cutleaf teasel prefers disturbed, open, sunny areas with moist to dry soils. It is commonly found along roadsides and in ditches. The plants form a rosette of hairy leaves and a long taproot before sending up the flower stalk. Cutleaf teasel derives its common name from the long, deeply cut, prickly leaves that form a cup around the stem. The stems are rigid and spiny. It can stay in rosette form for several years until it has stored enough resources to produce a flower stalk.
Cutleaf teasel produces a unique flower and seed head. The flowers are large, showy, oval-shaped and are enclosed by stiff, spiny bracts. The plant blooms from summer to fall. It also has the ability to form seeds on very short stalks after mowing, making management of this plant a challenge.
As a target weed on Minnesota's Noxious Weed Eradicate List, it's required by law that all above- and below-ground plant parts must be destroyed. Recommended management practices for cutleaf teasel include the following:
• Do not use seedheads in floral arrangements. Do not plant cutleaf teasel or intentionally move soil containing seeds of this species, including soil attached to equipment or recreational vehicles.
• For small infestations, hand-pulling and digging are management options, though the large taproots can be difficult to remove. Flowers and seed heads should be removed and dealt with according to the Minnesota Department of Agriculture/Minnesota Department of Health disposal recommendations.
• Mowing of the flowering stalks can disrupt seed production; however, mowing will not kill the rosettes and cut flower heads should be contained and disposed.
• Foliar applications of herbicide can be used on cutleaf teasel at the rosette stage. For specific herbicide recommendations, contact your University of Minnesota Extension Regional Office.
To report infestations of cutleaf teasel or any other noxious weeds on the eradicate list, please notify MDA by email at email@example.com, or voicemail at 1-888-545-6684 (toll-free).