How Weeds Make the Cut

By Jasmine Reimer

The difference between a weed and a desired plant is sometimes in the eye of the beholder. Dandelions to some are a nuisance and folks can spend a lot of time and money trying to get rid of them, but to others, the plant is seen as a useful gift both for pollination and making delicious treats and salads. What makes a noxious weed unique from other plan old weeds, is their designation in the Administrative Rules of Montana and a landowner’s legal responsibilities to control them. Noxious weeds are a special kind of problem. Not only are they non-native plants, but they are invasive, hard to control, and pose a threat to Montana’s economy, agriculture, recreation, and native landscapes. Many species that are noxious in Montana, are also listed as noxious in neighboring states. But how does a weed become a noxious weed?

It all starts with a threat. It can be a new invasion on private property, or county staff notices a growing problem with a species, or a public land manager from a neighboring state will find something new to the area. Once a weed becomes a threat, it is often brought to the attention of a local or regional coordinator. Luckily in Montana we have a robust network of coordinators who are in place to assist land managers with weed issues. These include the county weed districts, conservation districts, MSU extension offices, local NRCS offices, regional public land offices such as FWP, MDT, DNRC, DEQ, BLM, USFS, and others.* This network of coordinators can help to decide the potential threat of a species across all land ownerships in Montana. If the species is of concern, a petition for listing can be completed and submitted to the Department of Agriculture (MDA).

Petitions can be found on the Department website or from your local county weed district office. Questions about species lifespan, reproduction and growth, habitat, known distribution, and methods of control are all addressed in the petition. Petitions are reviewed by a working group each fall/winter. Members of this working group include University researchers, county weed coordinators, the State Seed Lab, state agency staff (FWP, MDA, MDT), Montana Invasive Species Council, Montana Weed Control Association, and other interested parties. This group is tasked with reviewing each petition and further evaluating the species against risk assessment criteria.

Completing a risk assessment on each petitioned species gives the working group a better idea of the potential impact to the entire state. Criteria includes habitat suitability, other regional, national, or international listings, current regional distribution and density, Montana county distribution and density, community types at risk of invasion and the impacts, beneficial uses, known expansion rate, plant characteristics such as growth rate, seed production, and life cycle, the types of effective control methods available, estimated cost per acre of control, and also which industries are or will be impacted. Once the species have been ranked, the working group meets to discuss and provide listing recommendations to the Director of the Department of Agriculture. During the meeting, petitioners are given a change to give a quick presentation or verbal argument on the species they are concerned about. If recommendations are approved by the Director, Department staff create and provide a draft ruling to the Department of Administration. All draft rulings are posted on the Secretary of State website, and are open for public comment, both written and in person. If there are no substantial changes made to the draft ruling, the rule is adopted by the State.

In addition to adding new species, species currently on the noxious weed list can be moved to another priority or be removed if circumstances change and they no longer pose a threat, or the control methods are no longer effective or economical. The noxious weed list is an Administrative Rule of Montana and therefor ties directly into the County Weed Act, which requires all landowners to control listed noxious weeds. Under this Act, counties have the authority to create an additional list of noxious weeds that are a threat to their constituents. These additions must go through a similar process as the State petitions, and counties are required to provide a public comment period before adopting a new noxious weed.

The main reason for listing weeds as noxious is not to force landowners to control these species, but to open the door for funding, education, and research. Federal, state, and local grant opportunities are available specifically for addressing noxious weeds. These species have no natural enemies here, and have escaped their original infestations, most of time at no fault of any individual landowner. These species are a true threat to Montana’s industry and way of life, which makes them particularly important to identify early, contain, control, and to research the most effective and ecologically sound methods for managing them. This responsibility doesn’t fall solely on our private landowners, but on all Montana lands and our neighboring states. By listing noxious weeds, we can pull in resources from not only local cooperatives but our state and federal partners as well.

The last species Montana listed as noxious was ventenata (ventenata dubia) in 2019. Vententa is a winter annual grass that has spread like wildfire across the west in the last few years and threatens agriculture and our native landscapes. Researchers and land managers from several neighboring states are joining efforts to find additional methods of controlling the impact and spread of this species. This year, two species were petitioned for listing: Scotch thistle (Onopordum acanthium) and puncturevine (Tribulus terrestrisI). Scotch thistle is widely distributed across Montana and seems to be an increasing issue in several counties. This thistle can grow up to 8 feet or more in height and can block access to areas due to its spines and robust stature. Puncturevine is an annual plant which can be toxic to some livestock, although not usually grazed because of the sharp spines that can puncture bike and truck tires. This plant grows well in disturbed areas like roadsides and pasture edges and is distributed across many Montana counties. This fall/winter the working group will be looking and assessing these two species for potential listing in the State.

If you have a issue with a weed on land you are managing, please contact your local weed district, conservation district, or MSU extension office to learn more about the species. Seek out resources like the Montana Natural Heritage Program, and other state noxious weed lists to assess the species distribution and potential threat. Call on your local weed boards or regional coordinators to help in completing a petition if listing a problem weed as noxious will help in the goal of keeping Montana’s industry and native landscapes healthy and productive. Any questions about the petition process or other issues related to noxious weeds in the state, please contact Jasmine Reimer at the Department of Agriculture.


MSU: Montana State University

NRCS: Natural Resources Conservation Service

FWP: Montana Fish, Wildlife & Parks

MDT: Montana Department of Transportation

DNRC: Montana Department of Natural Recourses and Conservation

BLM: US Bureau of Land Management

USFS: US Forest Service