Pitkin County has written a Noxious Weed Management Plan to provide guidelines for effectively managing designated noxious weeds which represent a threat to continued economic and environmental value of lands in Pitkin County. This plan implements the mandates of the Colorado Noxious Weed Act by detailing integrated management options for designated noxious weeds. Such options include education, preventative measures, good stewardship, and control techniques. The plan also includes weed identification, a geographic overview of areas of infestation in Pitkin County, enforcement, and a resource directory.

Integrated Weed Management is undertaken by land managers to incorporate more than one control technique into a well planned, more environmentally sound, coordinated program to reduce the impacts of weeds over time using a combination of the following methods: 1) Prevention, 2) Biological, 3) Mechanical, 4) Cultural, and 5) Chemical.

A balanced approach to successfully managing resources includes the following processes:

* managing the land to prevent weeds from invading

* proper identification and knowledge of weed species

* inventory, mapping, and monitoring of weed infestations

* making control decisions based on knowledge of potential damage, cost of control

method, and environmental impact of the weed and control decision

* using control methods that may include a combination of methods to reduce weeds

to an acceptable level

* evaluation of the effects and effectiveness of the control methods.

Prevention and detection is the highest priority weed management technique on non-infested lands. The Pitkin County Vegetation Managercan help you identify unknown plants that you find on your property. Strategies to prevent the introduction or establishment of noxious weeds in areas not already infested include: 1) watching out for ways that weeds can be introduced by topsoil, gravel, equipment, irrigation water

2) inspecting your land and identifying and eradicating small new infestations of weeds

3) continuous monitoring and evaluation to prevent recurrence of noxious weeds 

4) timely revegetation and reclamation of disturbed sites using appropriate native plant species.

Biological control is the use of living organisms to disrupt the growth of noxious weeds. These can be insects or grazing animals. The objective of biocontol is never eradication; it is reduction of a weed’s density to non threatening levels. After their introduction, biocontrol agents can take 5 to 10 years to become established and increase to numbers large enough to reduce the density of the targeted weeds. It is good to consult with the Pitkin County Vegetation Manager (970-920 5214) when introducing insects for the most recent information on their effectiveness. When you release insects you should continue to use other methods of control on the perimeter of the site since it takes years to see results and weeds will continue to reproduce.

Grazing animals such as goats are being used in Pitkin County as a means of weed control. Continual grazing of the tops of young plants can retard plant development, seed formation, and gradually deplete root reserves. Fencing the grazing animal prevents them from eating nearby grasses or shrubs. Once established, effective biological controls provide a long term and non toxic means to control weeds.

Mechanical control methods or management practices that physically disrupt plant growth include tilling, mowing, hand-pulling, shoveling, and chopping. Mechanical control must be done at the correct stage of growth to be effective. Often this needs to be done several times during the growing season and for many consecutive years. A major advantage of hand removal is that it occurs before plants set seed and so it reduces the soil seed bank over time. This method is often used in conjunction with other control methods.

Cuultural management involves methods or management practices which favor the growth of desirable plants over noxious weeds, including maintaining optimum fertility and plant moisture in an area, planting at optimum density and spatial arrangement in an area, and planting species that are most suited to a particular area. Crop rotation, reseeding, fertilization are all cultural practices that can enhance weed control. Reseeding to reintroduce desirable plants once weeds have been removed is important.

Chemical control is the use of herbicides. With chemical control, it is important to know what kind of weed you are treating. Herbicides have different modes of action. Herbicides are categorized as "selective" or "non-selective". Selective herbicides (i.e. 2,4-D, Banvel, Tordon, and many more) effect a specific type of plant. Non-selective (i.e. Roundup, Arsenal, Spike, and more) will affect all or most vegetation. Herbicides may also be selective based on the amount used. Effectiveness can be enhanced by applying chemicals at certain times of year.

If you are going to apply chemicals it is important to apply them as recommended on the manufacturer’s label, wear safety gear, and take necessary precautions to protect the environment.

Contact Pitkin County Vegetation Manager’s Office at 920 5214 or email jiml@co.pitkin.co.us for more detailed information on specific control techniques. They provide weed evaluation and consultation free of charge.

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