NOXIOUS WEED INFORMATION & FAQ

What are noxious weeds and why should I care about managing them? 

Noxious weeds are non-native introduced plant species that are capable of out-competing native, desirable species. As a result, this alters the native plant communities and ecosystems around us. They also reduce crop yields, reduce the value of agricultural products, negatively impact wildlife habitat, poison livestock (species dependent), decrease property value, increase irrigation costs and are a source of plant diseases and insect pests. 

Park County Weed District recognizes all 36 weed species listed on the Montana Noxious Weed List in addition to the species listed on the Federal Noxious Weed List.

Weeds and Montana Law?

• Montana Code Annotated 7-22-2116: Unlawful to permit noxious weeds to propagate -- notice required in sale
• Montana Administrative Rules: 4.5.2: Designation of Noxious Weeds

What are the Montana Noxious Weeds?

• MT Noxious Weed List - A list of the 36 noxious weed species in MT (no photographs)
• MWCA Weed I.D. - This has photographs and detailed descriptions of the 36 noxious weed species in Montana.

How do I know if I have noxious weeds on my property?

If you are comfortable with plant identification, please reference the following resources:

• MWCA Weed I.D. - This has photographs and detailed descriptions of the 36 noxious weed species in Montana.
• Weeds of the West - A vast field guide that goes beyond the 36 noxious weed species in Montana.
• Invasive.org - This has photographs and detailed descriptions of the 36 noxious weed species in Montana.

If you are not comfortable with plant identification, please contact the Park County Weed Coordinator and they will assist you in identification.

What can I do to manage the noxious weeds on my property?

Depending on the species of noxious weed(s) and the size of the infestation located on your property, management options could include:

•  Chemical - the use of herbicides to control noxious weed populations. Timing of applications is essential for success, consult with the Park County Weed Coordinator.
•  Biological - the use of approved biological agents that are natural predators of certain plant species. Biocontrol agents will aid in the suppression (not eradication) of noxious weed populations. Only available for select species and at certain times of the season. Consult the Park County Weed Coordinator for more information and also check out some Biocontrol Projects in MT that are good resources for information and agents.
•  Mechanical & Cultural - Hand-pulling, mowing, cultivation, crop rotation, mulching, cleaning lawn & farm equipment etc. Some mechanical and cultural techniques benefit noxious weed species rather than inhibit them. Consult with the Park County Weed Coordinator for best timing and best practice.

The optimum management approach is to integrate a variety of the management practices listed above into one management plan that is geared towards suppression & prevention of the noxious weeds on the property. Contact the Park County Weed Coordinator for information and assistance developing a noxious weed management plan that fits your circumstance.

Noxious & Toxic Weeds 

Many noxious weeds are listed due to their toxicity to animals including wildlife, livestock, and pets. 

• USDA news bulletin
• Plants Poisonous to Livestock in the Western States (PDF)
• Hoary Alyssum, common in much of Park County, is toxic to horses:  Hoary Alyssum: the most common poisonous plant to horses in Minnesota 

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