Noxious Weed Update: Murdock And Henbane
Author: Jessica Bushnell, Broadwater County Weed and Mosquito Coordinator
Noxious Weed Update: Burdock And Henbane
Jessica Bushnell
Broadwater County Weed and Mosquito Coordinator
This week, we will discuss two notably showy county-listed noxious weeds: Black Henbane and Common Burdock. These two species differ slightly from other plants on the list, as they were intentionally introduced to the United States by early colonists. While many noxious weed species enter the country accidentally, these two were brought here deliberately.
Black Henbane (Hyoscyamus niger), also known as stinking nightshade, belongs to the Solanaceae family, which includes tomatoes, potatoes, and deadly nightshade. It was introduced partly as an ornamental species and has since spread across the country. Black Henbane is a taprooted annual or biennial plant that reproduces solely by seed, with seeds capable of remaining viable in the soil for several years. The plant features deeply lobed leaves covered in greasy hairs, can grow up to 3 feet tall, and produces flowers that are brownish-yellow with purple veins that deepen to solid purple in the center.
All parts of Black Henbane are toxic to both humans and livestock. Its strong odor usually deters most animals from grazing, unless there is no other forage available. Black Henbane is not a strong competitor, so maintaining healthy vegetation can help prevent its establishment and spread. Because it has a taproot, small infestations can be managed by hand-pulling or cultivation. When hand-pulling, it is important to wear gloves and long sleeves to avoid skin rashes. For herbicide control, a strong surfactant is necessary to penetrate the thick leaf surface. Herbicide products containing the active ingredients chlorsulfuron or metsulfuron are effective options.
Common burdock (Arctium minus) was introduced to the United States as a medicinal plant, but it is now considered noxious due to its negative impact on livestock. Burdock is a large biennial or short-lived perennial that can grow up to 7 feet tall, with leaves that can reach 1 foot across. Its flowers are surrounded by bracts that mature into burs. These burs can entangle in the wool of sheep and can also irritate the eyes and nostrils of other livestock. Furthermore, burdock burs can persist on the plant stalks even after the seeds have been dispersed.
This plant produces a large number of seeds, so management strategies should focus on controlling it before it flowers. Because it has a taproot, mechanical removal of small patches is relatively straightforward. However, it is essential to ensure that the entire root crown is removed. Mowing can also be an effective control method, but it must be done before flowering, and the plants should be monitored, as they can flower again. Herbicides containing the active ingredients 2,4-D, dicamba, or metsulfuron are also effective.
Photos: https://fieldguide.mt.gov
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PhotoCredit: See captions
Image 1 Caption: Black Henbane
Photo Credit: Craig Althen
Image 2 Caption: Common Burdock
Photo Credit: Craig Althen
Image 3 Caption: Common Burdock
Photo credit: Matt Lavin
Image 4 Caption: Common Burdock
Photo Credit: Tom Watson
