Hi,

Thank you for your question. It appears that the plant pictured is Musk or Nodding thistle (Carduus nutans), a species of Plumeless thistles, it is also known as Cardo, Chardon pence, Bastard scotchbroom. It is invasive throughout the United States. 

These plant species have been declared prohibited noxious weeds in the state of Maryland. They must be controlled by anyone owning or managing land within the state. When these plants are mature, the seeds can be easily transported by the wind, water, and man, whether on clothes, accessories, or equipment. Noxious weeds damage our ecosystem,  negatively impact natural resources, threaten our farmers’ production, and negatively impact property due to infestations.

A noxious weed is a plant designated as such by an agricultural government authority. Their aggressive way of reproducing make them extremely hard to control or eradicate. Control practices are required by law and include mowing, and/or treating with approved herbicides.

The key to controlling plumeless thistle is the same as most other thistles: keep the plant from going to seed. If the rosette stage is prevented from producing a stalk during the second year, the individual plant will die. Vigilance and repeated mowing during the growing season can prevent the stalk from emerging. Young rosettes that may emerge can  be removed by hand; be sure to remove the entire taproot whenever possible. Use a shovel to get rid of taproot.  Chemical applications of the herbicide glyphosate in the fall during the rosette stage has also been effective. This herbicide will kill any plants it comes in contact with,  so it should be targeted only to the leaves of the thistle plant.  Carefully follow the directions, legal and safety precautions when using herbicides. It is important to remember that plumeless thistle seeds can be viable in the soil for up to ten years, so surveying an area that previously had these plants as well as adjacent areas is recommended to prevent further spread.

If hand pulling or cutting, protect yourself by wearing long pants and sleeves, close toed shoes or boots, leather gloves that come above sleeve cuffs.  Dispose of plants and roots in black plastic bags, tying the bag securely and putting it into the trash not compost. 

Christine