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.