Get A Handle On Noxious Weeds

by Leah Opitz, Prior SLV Weed Management Association Coordinator

First published in the Valley Courier, Jan 29, 2013

Anyone who is a homeowner, farmer, rancher, or has any kind of property whatsoever here in the San Luis Valley has probably dealt with weeds in some way, shape, or form — whether it’s pulling dandelions out of a flowerbed week after week or treating a garden with Round-up.

So what is a noxious weed?

By definition, a noxious weed is any non-native plant that is harmful to agriculture, natural habitats, humans, and/or livestock. Most noxious weed species were introduced into Colorado by accident or mismanagement and have been creating problems for farmers, ranchers, conservationists, and recreationalists for many years. Noxious weeds have been able to spread into San Luis Valley, displacing the native plant species.

The reason for their success is that they are able to out-compete the native species. Since they are newcomers to the Valley and to the State of Colorado, their normal “predators” aren’t around, such as insects or foragers that would feed on them in their native areas. With no natural biological control, invasive species are able to invade large areas of land at a rapid rate.

Another characteristic of noxious weeds that make them dangerous here in the Valley is their ability to survive with very little water. The thistles and knapweeds that are commonly seen along highways and ditches in the Valley are able to not only tolerate, but flourish in drought conditions while the native plants are being stressed out to the max.

So what can be done to manage noxious weeds? Noxious weeds can be controlled through a series of chemical, mechanical, and biological treatments. Pulling or mowing certain species, such as spotted knapweed, can be successful when mowed while they are in a flowering stage. However, it is likely that the knapweed will return unless the removal is followed up with herbicidal treatment. Also, knapweeds contain a toxin that can cause severe skin irritation so not only is it important to always wear gloves when pulling weeds but also know what you are pulling.

Other weeds, such as Canada Thistle, will not respond to pulling and mowing. In fact, pulling thistle can make the problem worse. Knowing exactly what is growing in a lawn, garden, pasture, or fallowed field is very important in order to determine the best treatment method.

There are over 30 noxious weed species in the Valley that are in need of proper, coordinated management which is why the San Luis Valley Weed Management Association was created. The SLVWMA is a group of public and private partnerships that was created to promote awareness and management of noxious weeds through local and regional initiatives here in the SLV.

The goal of the SLVWMA is to manage and control noxious weeds cooperatively throughout the Valley, regardless of geographic or political boundaries, in order to promote ecological and economic values. By partnering up with local weed districts, conservation districts, private land owners and public agencies, the SLVWMA is working hard to establish an effective noxious weed management plan for the Valley in order to preserve agricultural production, recreational space, natural resources, and overall environment.

With very little precipitation and the possibility of the drought continuing, 2013 is shaping up to be a big year for noxious weeds. That is, they could become an even bigger problem throughout the Valley. Therefore, the SLVWMA is going to be more active than ever by focusing on education, as well as to continue to focus on weed management and eradication.

First, SLVWMA will be contributing monthly articles to the Valley Courier on a “Weed of the Month.” This will give readers an opportunity to learn more about the invasive species in the Valley, how to identify them, and how to manage them.
Second, SLVWMA will also be hosting educational seminars and weed identification tours in the spring, summer, and fall. SLWMA will also continue to support the weed management efforts of the conservation districts, counties, weed districts, ditch and canal companies, landowners and home owners. Through a great deal of collaboration, SLVWMA and its partners hope to get a good grasp on noxious weeds this year.

Don’t Let This Weed Become the Bane of Your Existence

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.

More information can be found on this weed at Colorado Department of Agriculture’s Noxious Weeds webpage ( ag/weeds) and other websites: Colorado Weed Management Association (www.cwma. org), San Luis Valley Weed Management Association (, and Rio Grande WatershedCenter Conservation District (http:// riograndewatershed. org/center.html). For more information about weed management in the San Luis Valley email the San Luis Valley Weed Management Association at This email address is being protected from spambots. You need JavaScript enabled to view it..

El Pomar Meeting

Letter to the Editor. First Published in the Valley Courier, May 20.

Last Monday more than 25 representatives from Valley non-profits attended El Pomar’s “Serving as an Effective Board Member” hosted by the San Luis Valley Weed Management Association. Senior Vice Presidents Matt Carpenter and George Guerrero walked the group through legal obligations, life cycles of non-profit Michelle Le Blanc, SLVWMA Coordinator Darrel Plane, SLVWMA Board Chair Myron Price, Board member James Clare, Board member Brenda Anderson, Board member Pete Magee, Board member Danny Neufeld, Board member organizations, financial management, as well as board and staff roles and responsibilities.

Not only would we like to thank El Pomar’s Carpenter and Guerrero, but also the organizations which sponsored the evening’s meal served by Dos Rios. Those sponsors are: Don Vigil at Rio Grande Savings and Loan; Shon Davis at San Luis Valley Federal Bank; Tom Scarlett with the San Luis Valley Antique Iron Club; and Kay Harmon with the Monte Vista Chamber of Commerce who also opened up their conference room for the gathering.

Thanks to our instructors, sponsors, and participants for sharing your time, treasure and talent with the people of the San Luis Valley.

Michelle Le Blanc, SLVWMA Coordinator
Darrel Plane, SLVWMA Board Chair
Myron Price, Board member
James Clare, Board member
Brenda Anderson, Board member
Pete Magee, Board member
Danny Neufeld, Board member