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Pagosa Springs
Tuesday, May 30, 2023

Stewardship begins in your backyard

By Ethan Proud
Archuleta County Weed
and Pest Department

There are few management problems that span the multi-hundred acre ranches all the way to patio lots around condos, and noxious weeds are one of them. 

According to the Colorado Noxious Weed Act (35. 5-5), all landowners in Colorado have a legal responsibility to manage noxious weeds on their own property. 

So, what is a noxious weed? A noxious weed is a non-native, invasive plant that is mandated for control as it is either detrimental to our native ecosystems, threatens agriculture and can damage human health. Noxious weeds affect wildlife, waterways and recreation. 

What makes one non-native plant worse or better than another? Some nonnative plants fill a role in our ecosystems or do not spread from ornamental planting. Noxious weeds typically have dispersal methods that favor long distances, long seed dormancy periods and prolific seed production. One of our most prevalent weeds, musk thistle, is the poster child for all of these traits. It can produce over 100,000 seeds, which are wind dispersed and can travel miles, and the seed may lay dormant in the soil for decades.

Management techniques for noxious weeds vary, but there are three main kinds: chemical, manual or biological. Both organic and conventional herbicides fall into the chemical category. All herbicides used must be labeled for use, which will detail risks to the environment and how to safely use them. 

Household vinegar is not a labeled herbicide and therefore its use is illegal, but you can purchase horticultural vinegar which is labeled and is much stronger. Always wear personal protective equipment when handling or applying herbicides. 

Manual control involves physically removing the plant, whether it is using a good, old shovel or a brush hog. Manual control should be limited to annual and biennial weeds as they do not spread from a creeping root system. Mowing a plant like leafy spurge can encourage root growth. Hand-pulling or mowing a creeping perennial can be done, but it requires years of diligence and labor. 

Biological control is the use of pathogens, insects or animals to control a pest. The USDA Animal and Plant Health Inspection Agency studies and regulates insects and pathogens introduced from the invasive weeds home range to determine whether or not they can be safely employed to manage noxious weeds. Biological controls must be host-specific, meaning that they will only eat the target species and will die in its absence. Goats are also a form of biological control and can graze indiscriminately for the most part and can even eat plants like leafy spurge which are toxic to cattle and horses.

So, why does it matter if an invasive weed is on personal property? Weeds spread prolifically: leafy spurge ejects its seeds 15 feet from the parent plant, musk thistle seeds can become wind-borne and travel for miles on a good breeze, houndstongue seeds stick to animals and clothing like Velcro and can be spread along migratory paths and trails. On top of that, seeds can stick to the bottoms of vehicles, tires and shoes — when you leave your house and travel to public lands to recreate, you can spread weeds along the trails. The trails around Williams Reservoir and to Four Mile Falls are littered with weeds that are spreading further and further from the trail each year. When going out of doors, add PlayCleanGo to your Leave No Trace ethics and clean off your equipment and brush off your shoes to prevent the spread of noxious weeds.

How do weeds impact our natural areas and recreation? Invasive plants crowd out native vegetation and can reduce wildlife visitation and bird nesting, and can reduce access to rivers. Salt cedar or tamarisk can use more than 100 gallons of water per day and their leaf litter secretes salt which makes the ground inhospitable to other plants such as cottonwoods and willows. Russian knapweed roots release chemicals which kill other plants, a trait called allelopathy, and cause chewing disease in horses.

What can you do to help prevent the spread of weeds? Become familiar with the noxious weed list, either by visiting the Archuleta County, Colorado Department of Ag, or the Colorado Weed Management Association web pages, and identify the invaders that are present on your property and select the proper management technique and timing. The Archuleta County Weed and Pest Department can help you identify weeds and the correct control method — whether you are pro herbicide or not. If you notice an invasive plant on your neighbor’s land, kindly let them know and educate them. Managing noxious weeds is a monumental task and many hands make for lighter work. Not to mention, weeds know no boundaries and your neighbor’s weeds will quickly invite themselves over to your land. When controlling weeds, it’s important to revegetate with native plants and pollinator species to replace what was lost due to the noxious weeds. 

Be a steward of our county’s precious resources and manage noxious weeds in your backyard.

Musk thistle • Most prevalent weed in Archuleta County. • Invades disturbed areas and establishes a monoculture. • Not suitable forage, displaces wildlife. • Reduces flower diversity, which negatively affects pollinators. • Produces upward of 100,000 seeds that can lay dormant for 50 years.
Leafy spurge • Ejects its seed 15 feet from parent plant. • Contains caustic sap that can blister skin and is toxic to livestock. • Spreads from an extensive root system. • Reduces animal visitation and nesting behavior in birds. • Reduces property value (a ranch in Oregon was sold for 80 percent less of its value because of this species).
Houndstongue • Toxic to horses. • Causes liver disease. • Animal distribution via Velcro-like seeds which transports it along migratory routes. • Not suitable forage for wildlife. • Displaces native vegetation.
Russian knapweed • Toxic to horses. • Causes chewing disease, which destroys the part of the brain responsible for motor movements of the mouth; horses starve to death. • Secrete chemicals from their roots to suppress the growth of other plants. • Spreads from an extensive root system. • Reduces property value.
Photos courtesy Jamie Jones
Yellow toadflax • Crowds out native vegetation. • Not suitable forage for wildlife. • Can be toxic to wildlife if consumed in large quantities. • Reduces property value.

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