- How are noxious weeds different from regular weeds?
Federal and/or State law designates plants as
"noxious" if they are overly aggressive, difficult to
manage, parasitic, poisonous, carriers or hosts of serious insects
or diseases. Noxious plants may also be non-native, new to, or not
common to the United States. In most cases, noxious weeds have a
direct impact on croplands. The BLM is also concerned with other
invasive weeds that cause harm, but may not necessarily be designated as Federal
or State noxious listed weeds.
Are these noxious or invasive weeds in the United States noxious
or invasive in their host countries?
For the most part, no. These plants have existed for centuries in
their host country, but their populations have been kept to
manageable levels naturally by other plant competition, insects, pathogens and
a host of other predators. When plant populations in these countries
of origin increase, insects and other predators increase accordingly
to help keep them in check.
How did these weeds get here and where did they come from?
Most of these weeds came from Eurasia and were transported to the
United States both accidentally and intentionally. Accidental
transport occurred in the ballast of ships, in the fleece and hair
of livestock, in clothing, and as contaminants in seed lots. Other
weeds came in as medicine, dyes, and ornamental plants.
How are these weeds spread?
Weeds are spread in any number of different ways: by human
activity, birds, animals, wind, water, vehicles, and seed and plant
parts, to name just a few.
If a plant is noxious or invasive, does that mean I can remove or
replace it?
You can remove any weed if it does not meet your landscape or
land management objectives. The local land management plan,
Environmental Protection Agency or
State regulations will determine the appropriate tools and methods
for removal.
What are the health hazards of some of these weeds?
Health hazards to the public include the following examples:
- Leafy spurge can cause blindness and skin irritation or
blisters.
- Poison hemlock is extremely poisonous if eaten and may cause
death in a short period of time
- Water hemlock, especially the root, is extremely poisonous if
eaten, causing death in a short period of time
- Jimsonweed and black henbane have hallucinogenic properties
and can cause death.
- Many weeds cause allergic reactions in susceptible humans
In addition, weeds can present other public health hazards.
For
example, dense weed growth along public rights-of-way can obstruct
vision leading to vehicle collisions
How can I manage noxious or invasive weeds?
There are several opportunities and strategies that are effective
in the control and management of noxious or invasive weeds,
including:
- making others aware of the
problem and how they can help will greatly increase your chance
for success;
Prevention and Detection - by taking certain precautions
we can prevent weeds from encroaching and occupying lands that
are currently weed-free;
Inventory - before you treat weeds, you must know where
they are and the extent of the infestation;
Planning - knowing whom to work with, how to treat the
area, and how to manage the land after it is treated is vital to
the success of your project;
Treatment - knowing which tools to use for each weed in a
specific situation is imperative to the success of your project;
Coordination - two or more landowners or land managers
working together may help reduce costs and achieve a higher
degree of success; and
Monitoring, Research, and Evaluation - keeping track of
what works and what doesn’t will prevent you from repeating
mistakes in the future and may help others in their efforts.
Once I know where these weeds are, how can I treat them?
There are four treatment methods that can be used to control, and
in some cases, eradicate weeds.
- Physical (hand-pulling, cutting, mowing, digging, disking,
plowing, burning, etc)
- Biological (use of insects, domestic animals, pathogens, etc)
- Chemical (use of herbicides)
- Cultural (development of weed prevention programs, weed free
forage, weed free gravel, vehicle washing, etc).
Often, you may obtain best results by using several of these
control methods together. For example, burn and reseed in the first
year, spot treat remaining plants with herbicides in the second
year, change to fall grazing and restrict vehicle use in the area.
You may obtain advice on control methods, as well as specific, local
concerns from local land managers, extension specialists, and weed
control specialists. After performing weed control, you may find it
necessary to perform site restoration.
Where can I get insects for noxious or invasive weeds?
There are several companies that specialize in biological control
agents. You can find their addresses and phone numbers via the
Internet. Local land managers and weed specialists may also know
where to get insects that are established locally.
If I have a small patch of a noxious or invasive weeds on my
property, what is the best way to control it?
There is no one particular control method that will work on all
weeds. Therefore, it is important to speak with your local weed
control specialist or county agent to find out what approach is best
to deal with your specific weed problem. Several states have
published weed control handbooks that are excellent sources of
information.
Does the BLM use herbicides to eradicate weeds?
Yes. Currently all Western BLM land managers (except Oregon) are
managing weeds under the guidelines of the Final Environmental
Impact Statement for Vegetation Management on BLM Lands in Thirteen
Western States (1991). Oregon is managing weeds under the guidelines
of the Final Northwest Area Noxious Weed Control Program EIS (1985)
and the Finale Supplemental EIS for Noxious Weeds (1987). These
documents provide for integrated pest management, which includes the
use of herbicides, on lands managed by the BLM.
What should I do if I find a noxious or invasive weed?
Always make sure you record and mark the location, species (if
known) and the approximate size of the population. You should then give this information to the
nearest land management agency or extension service.
If you are sure of the identity of a noxious or invasive weed and
know whether it is an annual or biennial, you may decide to pull a
small patch. Remove the mature plants (below the root crown) then
bag and remove it for proper disposal, which will destroy any viable
weed seeds. You may remove immature plants without buds or flowers
in the same manner, but leave them out to dry on site. Generally,
perennial weeds do not respond well to this treatment, but removal
of top growth may stop seed dispersal for that season or until full
treatment. Even if you pull the entire weed population, always
record site information and provide it to the responsible land
management agency.
If you are unsure of what the plant is and decide to take a
sample in for identification, take care in the collection process.
Some plants are poisonous. If you are unsure of the identity, you
should assume that it is. Wear gloves and don't let the plant touch
bare skin or to get near the eyes. To aid in identification, collect
the entire plant, including the root and flowers or buds. Place the
plant in a plastic bag, and keep in a cool, dark place while
transporting to be identified. You should keep your hands away from
your eyes and mouth until they can be washed thoroughly with soap
and water. You should also wash any tools used for collection.
Where can I get more information on weeds, specifically which
species are considered noxious weeds for each state?
The Invaders Data Base http://invader.dbs.umt.edu
developed by
Peter Rice, University of Montana, Division of Biological Sciences,
Missoula MT 59812, biopmr@selway.umt.edu, Tel. 406-243-2671, is a
distribution database for exotic plant species and weed natives in
all Northwestern states. It provides a list of all known noxious
weeds in the northwest states and links to web sites that list
noxious weeds for all other States and Canada. Also, each State
department of Agriculture maintains a list of noxious weeds. In many
cases, this information is available through the agricultural
extension service.
Where have there been success in noxious or invasive weed
control?
There are a number of success stories. Click on the following
links for examples (Link to success stories in various districts, or
Dept of Ag sites - Tansy Ragwort in Oregon, Salt Cedar in Texas,
etc)
What chemicals may be used on noxious weeds?
For more information, contact the Chemical and Pharmaceutical
Press, Inc. website http://www.greenbook.net
or (Link to National
Pesticide Telecommunications Network website - http://ace.orst.edu/info/nptn/, email -
nptn@ace.orst.edu and EXTOXNET at http://ace.orst.edu/info/extoxnet/.
Consult with your local BLM office for information on approved
chemicals and application methods for use on BLM lands. In addition,
your local weed specialist or extension office are excellent sources
of herbicide information.
What non-chemical treatments work well on noxious weeds?
You may contact the weed or agriculture extension specialist in
your area for information on integrated weed management treatments.
Is eradication possible for all species?
Weeds have overrun so much land that it is physically and
financially impossible to eradicate them all. With adequate funding,
however, control is possible.
What biological control agents are approved for use in the US?
The Western Society for Weed Science has published an excellent
book, "Biological Control of Weeds in the West," which
provides information on approved biological control agents, target
species, availability, etc. You may be obtain this book from Western
Society of Weed Science at P. O. Box 10342, Helena MT 59604. You may
also obtain additional information from State Departments of
Agriculture.
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