By Lamar Optiz, Former District Conservation Technician Center Conservation District. First published in the Valler Courier, May 14, 2014.
Valley Bane is an old-fashioned word that has various meanings, including killer, poison, death, woe, and curse. It can be used to mean “a source of harm or ruin.” This latter meaning could be applied to a noxious weed that occurs in the San Luis Valley called black henbane. This plant competes with other plants for moisture and nutrients and also produces a persistent ground litter that affects the germination and growth of native or more desirable plants.
Saguache County has had one of the largest populations of black henbane in Colorado , but according to recent sightings, it is now fairly widespread in the southern part of the San Luis Valley as well. This plant species is listed as a Colorado List B noxious weed; therefore, management plans seek to prevent the continued spread of the weed.
Like many invasive species and noxious weeds, black henbane was introduced into the United States as an ornamental and medicinal herb. It has been used as a medicinal herb since the 10th century, but primarily for external applications. The downside is that all parts of the plant are poisonous to both livestock and humans if ingested internally. Livestock usually avoid it, because the foliage has a foul odor.
Typical habitats for black henbane include disturbed or overgrazed areas, road rights-of-way, pastures, riparian areas, and abandoned gardens. It also grows in moist soil types and likes soils that are well-drained or sandy. Black henbane is a member of the nightshade (Solonaceae) family and may be an annual or biennial plant usually emerging in May, blooming June through September. The flowers are a brownish-yellow in color with a dark purple center and veins and grow in two rows along stems or racemes that originate out of the axils of the upper leaves. The seed pods or fruit appear in the fall, are pineapple-shaped and produce hundreds of seeds that can remain viable for 1 to 5 years. Mature plants may reach 3 feet in height. The leaves can be coarsely to shallowly lobed with sticky hairs.
Avoiding disturbance and overuse of lands is the most effective measure used to control black henbane. The plants should be controlled prior to seed production in the spring and early summer using mechanical and/ or chemical controls. The herbicide Milestone (aminopyralid ) has been successful after consecutive years of treatment at the flowering stage in Saguache County. Combinations of treatments are often most successful, for example, cutting the mature plant off below the flowering stalks and then spraying the remaining foliage with an herbicide. Follow-up treatments may be necessary to eliminate missed or late-bolting plants. Maintaining a cover of perennial plants and preventing the weed from producing seed are the most effective means of control. Though biological control is an effective control method for some noxious weeds, there is no known biological control agent known for black henbane.