Working together to strengthen and support noxious weed management efforts in Montana.

Centaurea solstitalis

Invasive plants in wildland ecosystems: merging the study of invasion processes, with management needs

Wednesday, July 17th, 2013


Introduction: Increasing numbers of non-native species threaten  the values of wildland ecosystems. As a result, interest in and  research on invasive plant species in wildland  settings has accelerated. Nonetheless, the ecological and economic impacts of non-native species continue to grow, raising the question of how to best apply science to the regulation and  management of invasive plants. A major constraint  to controlling the flow of poten­tially undesirable  plant  species is the lack of a strong  regulatory framework  concurrent  with increases in trade volume. To address this, ecologists have been developing models to predict which species will be harm­ful to wildland  values and are working with the horticultural industry  to apply this information to the sale of species. The management of established invasive plants is hampered  by conflicting goals, a lack of information on management outcomes, and a lack of funding. Ecologists and weed scientists can provide a scien­tific basis for prioritizing species for control and for managing species composition  through  the application of  control  technology,  which  can  take  place  simultaneously with  the  manipulation of  the  ecological processes that influence community susceptibility  to invasion. A stronger scientific basis for land management decisions is needed and  can be met through  nationally  funded  partnerships  between university and agency scientists and land managers.

Authors: Carla MD’Antonio, Nelroy  E Jackson, Carol  C Horvitz ,and Rob Hedberg

Download and read the complete Research Report on Invasive Plaints in Wildland Ecosystems..

Weed Invasion – New Poster

Wednesday, June 5th, 2013


Are you looking for a educational poster?   MWCA and many partners put together a new poster that is available for use to help get the word out to the public.

Download Noxious Weed Education Poster and print it and use it in your area.

Update Yellow Starthistle in Stillwater County

Wednesday, May 1st, 2013


Update: April 29, 2013

Update:  Yellow Starthistle in Stillwater County

Since yellow starthistle was first discovered in Stillwater County in 2010, there have been a number of efforts at eradicating and monitoring this noxious weed.  In addition to the description below of the successful weed pull in April of 2010, the area was treated with herbicide in June and July of 2010.  The County also conducted a widespread education campaign to inform residents of the presence of yellow starthistle.  The following season of 2011, county employees, assisted by MSU Extension, Bozeman were unable to find any new plants in the area.   In 2012, two separate searches were conducted by the Weed District and Jane Mangold of MSU Extension, Bozeman and we are happy to report no new infestations!  This summer, we are offering a reward of $50 to people who find new infestations of invaders like yellow starthistle.  We will continue to check the area in which it was initially found but are hopeful that this round of yellow starthistle invasion is history!

Original Article: May 11, 2010

A crew shows up to help Stillwater County.

A crew shows up to help Stillwater County.

As many of you are aware Stillwater County Weed District recently discovered an outbreak of Yellow Starthistle. As part of our immediate call to action we hosted a weed pull on April 22 at the reported location. We were very appreciative to the many counties who participated in this event. The day was a typical Montana spring day but we were able to accomplish all that we had hoped. In fact we gathered a total of 28 garbage bags of old plants. I would especially like to express my gratitude to all those who took time away from their busy schedules to come together for some friendly conversation and hard work. With your help as well as a the concerned land owners of Stillwater County we have great hopes of successful control, management and eradication of our unwanted guest.

Stacy Barta finishes another bag of yellow starthistle.

Stacy Barta finishes another bag of yellow starthistle.

Many Kinds of Knapweed Found in Montana

Friday, September 2nd, 2011


The September MSU monthly weed post focuses on knapweeds.  Did you know that there are eight kinds of knapweed found in Montana?   Dr. Jane Mangold’s publication this month takes the flower of each of the knapweeds and teaches us how to tell the difference.

Download this two page publication today.   Learn how to tell spotted knapweed from brown knapweed.

MWCA has pages devoted to identification of the knapweeds  listed on the Montana Noxious Weed list:  Russian Knapweed, Spotted Knapweed, Diffuse Knapweed and Yellow Starthistle.

Yellow Starthistle – MSU July Monthly Weed Post

Monday, July 18th, 2011


Yellow starthistle  is featured in the July monthly post from MSU publications on noxious weeds. Download and read this informative publication. This weed was found in two counties last year: Stillwater and Beaverhead.  There are lots of efforts this year to make sure that this nasty invader doesn’t pop back up in Montana, including a “Yellow Starthistle Weed Watch Day” August 4th in Stillwater county.   The public is invited to participate and details are on on the download.

Visit the MWCA Weed ID page for details about yellow starthistle. Contact your local weed coordinator if you think you find it in your area.  There may be a reward.

Weed of the Week Series – Yellow Starthistle

Thursday, June 17th, 2010



Yellow starthistle is found close to the western border of Montana but has not yet successfully infested the majority of the state.  Due to its close proximity to us we need to seriously consider the potential it has to move in and rapidly infest our land.  It is thought that it was introduced to North America from the Mediterranean region, through contaminated seed.  Yellow starthistle is present in 23 states with the largest infestations in California, Idaho, Oregon, and Washington.  There are approximately 12 million acres infested with yellow starthistle in California and over 200,000 acres infested in Idaho.  Until recently only a few yellow starthistle plants had been found within Montana.  Last fall a small infestation was found in Beaverhead County.  A few weeks ago a larger infestation was discovered in Columbus, in Stillwater County.  This infestation is scattered throughout 10 acres.  This spring/summer will tell if the infestation is more widespread than what was found through identifying the standing dead plants remaining from last years growth.


The spines that are located below the yellow flowers interfere with grazing, recreation, and wildlife management.  This plant is also toxic to horses.  It causes a chronic and potentially fatal neurological disorder that is commonly called “chewing disease”.  It earned this name due to the loss of the ability to apprehend and chew food.  However, swallowing is unaffected.  The animal will eventually starve to death due to this if it does not die due to inhalation pneumonia first.  There is no specific treatment to date and the irreversible localized necrosis in the brain gives a very poor prognosis.


Yellow starthistle is a winter annual with a deep taproot (up to depths of 6 feet).  Seeds germinate in the fall and overwinter as rosettes.  Fall germinated seedlings monopolize soil moisture and are highly competitive for nutrients and space.  In the spring, the rosettes will bolt producing branched erect stems with terminal flower heads.  Yellow starthistle is capable of growing in either wet or dry conditions and can respond rapidly to changing conditions.  It will produce large plants with abundant seeds during wet years and small plants with few flowers and seeds in dry years.

The flower heads consist of 20-50 small yellow individual flowers that are tightly clustered appearing as a single flower at the end of each branch.  Radiating out from below the flowers are up to 2 inch long straw colored spines.  The grayish to bluish-green stems are rigid and appear winged due to extending leaf bases.  The stems and leaves are covered in cottony hairs given the plant a whitish appearance.  The plant can be anywhere from 2-6 feet tall.

What can you do?

This plant is a new invader to Montana and therefore requires immediate action and hopefully eradication.  If you have found or think you have found yellow starthistle contact your county weed coordinator before initiating any control.  This plant is a rapid colonizer and germinates quickly under most conditions.  Dense seedbanks and length of seed viability make this plant extremely difficult to control and this is why it is important to locate new infestations and eradicate them prior to seed production.  The seeds can remain viable in the soil for up to 10 years.

Herbicides are the recommended method and most effective means of control when applied before the plants have flowered.  For recommendations on herbicide selection and timing contact the weed district and always follow the label directions.  Persistent hand pulling can be effective, as long as no flowers are allowed to go to seed.

Visit the MWCA Weed ID pages for additional information and pictures of yellow starthistle. If you have any questions about yellow starthistle or any other noxious weeds please contact your local county weed district.

This series of articles was developed by Ravalli County.  If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.

Yellow Starthistle Publication from MSU

Tuesday, March 23rd, 2010


If you are looking for more information on yellow starthisle download a copy of the MSU Extension publication “Watch Out for Yellow Starthistle.”