Contain, suppress, eradicate: noxious weed goal-setting

By Ethan Proud
PREVIEW Columnist
Once you have established that you have a noxious weed infestation on your property, you have to figure out what to do with it. Sometimes this is discouraging once you’ve done the research or consulted with local experts.
Musk thistle seeds survive in the soil for 50 years and controlling them can be a daunting task, especially since it is the most widespread weed in Archuleta County. The State Noxious List has weeds designated for different types of control. The A-list weeds must be eradicated, the B-list species should be contained and eradicated, and those on the C list should be suppressed and their spread limited.
Eradication is fairly simple: All standing plants must be destroyed and the site monitored for the length of time the seeds are viable. This is feasible when you have discovered your first invader and it is a single plant. Treat it or pull it before it flowers and watch the area to see if more weeds appear. Seeds can be moved by wild animals like birds, so a weed on your property isn’t an indicator that you have done something wrong.
If you discover that the white daisy you liked that is all over your yard is oxeye daisy, which is noxious and extremely aggressive, containment is the best course of action. Depending on the size of the property in question, it can be treated in a single season or day. If it covers a number of acres, begin at the edges of the infestation and create a 50-foot buffer zone and work inward each year. It may be tempting to start at the epicenter of the invasion, but this will only allow the weeds to spread and you will constantly be chasing a moving target.
Each year, work inward, monitoring the area treated the previous year. It is wise to treat property boundaries, driveways and heavily trafficked areas first to prevent further spread. As tempting as it may be, do not treat your neighbors’ land for them unless you have their explicit consent. They may have an organic farm, animals or other reasons for not using herbicides. Also, if you misapply the herbicide and do not follow label directions, it is a federal violation.
Weeds that may be hand-pulled or mowed can also be contained following the same procedure as with chemical applications. Never mow a plant that has already gone to seed unless you can contain those seeds and prevent them from being flung by the blades of the mower.
Suppression of weeds simply means that their spread is limited, as well as seed production. If you have mullein on your property, you might like how it looks or use it as an herbal remedy. That is fine, but do your part to prevent its spread. The seeds persist in the soil for up to 100 years and you won’t need to keep replanting. Cut all seed heads off the plant and dig up rosettes that are escaping down your driveway. Suppression can also be achieved by using biological controls. Not all weeds have a biocontrol option; check out the Colorado Department of Agriculture website to request biocontrols.
Moving from noxious (legally mandated control) to all other weeds, goal-setting is more subjective. A weed is defined as a plant out of place. Weeds do not exist in biology, which favors the strongest species or punishes the weakest.
A diversity of plant species is a sign of a healthy ecosystem and seasonal and yearly changes are to be expected. Sometimes a change in dominant plant species is part of the natural cycle and they are replacing the nutrients taken from the soil by the dominant species the previous years. In drier years especially, you may see a different variety of plants growing. Your reason for controlling weeds is usually the deciding factor on which goal is right for you.
Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.

This story was posted on July 29, 2019.