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

Priority 2A Weed

Blueweed: MSU March Monthly Weed Post

Thursday, March 10th, 2011


Blueweed is the noxious weed featured in the March monthly post from MSU.   Download and read this informative publication.  The last page includes a crossword puzzle to quiz yourself on your blueweed knowledge. Visit the MWCA Weed ID page for details about the weed.  At this time is is only known to be in six counties, if you think you find it contact your local weed coordinator.

Weed of the Week – Hoary Alyssum

Thursday, November 11th, 2010


Hoary alyssum is native to Europe and Asia.  It is often confused with another noxious weed, perennial pepperweed.  They have similar shapes and seed attachment.  These plants are both included in the mustard family and are therefore related.  Hoary Alyssum is a newly state listed noxious weed in Montana.  It was listed in 2008 and seems to be popping up everywhere.  This plant can be found throughout Minnesota, the upper midwest, and the western states.  It prefers disturbed sites but can also be found in meadows and pastures.  It is adapted to dry conditions on sandy or gravely soils.  Hoary alyssum prefers direct sunlight but will tolerate shade.

Concerns Hoary Alyssum can be an annual, winter annual, biennial, or a short-lived perennial and is spread only by seed.  It spreads rapidly because each plant produces many seeds.  It has been found to be toxic to about half of the horses that ingest it.  If a horse is going to react to it they will in 12-24 hours after ingested.  The signs include swelling of the lower part of the legs, fever of 103 or higher, warm hooves, pronounced digital pulse, stiffness of joints, reluctance to move, and very rarely death.  Horses have reacted to both fresh plants and plants that have been cut in hay.

Identification The rigid stems are hairy, 1-3 feet tall, and grayish-green in color.  These stems branch many times near the top.  The alternate leaves are oblong, also grayish-green, and covered in rough hairs.  The white flowers are clustered at the tips of the branches.  Each flower has four petals that are deeply divided.  There are seed pods located up the stems below the flowers and they are hairy, oblong, and appear to be swollen with a point on the end.

What can you do? A healthy community of native plants will definitely help prevent the establishment of hoary alyssum.  Hand pulling or digging and mowing can be effective in controlling small infestation but must be done before flowering.  There are several effective herbicides but often more than one application is necessary for control.  For best results, herbicide must be applied before flowering.  If you have infestations of hoary alyssum and they are already flowering hand pulling and mowing before seed set is the best option.  If you have questions about this plant or any other plants please contact your local county weed district.

Visit the MWCA Weed ID pages for additional information and pictures of hoary alyssum.

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.

Weed of the Week – Orange Hawkweed

Thursday, October 28th, 2010


Orange hawkweed is native to Europe and likely came to the U.S. as an ornamental.  It has since escaped cultivation and was first found to be a problem in Spokane, WA in 1945.  There are serious infestations in northwestern Montana, northern Idaho, and northwestern Washington.

Orange hawkweed’s clusters of bright orange to orange-red dandelion-like flowers make it unmistakable.  The orange flowers follow the path of the sun throughout the day and if the plant is broken off it exudes a milky latex substance.  There are several native species of hawkweeds in Montana but orange hawkweed can be distinguished by its orange flowers (it is the only species with orange flowers), bristly hairy leaves (most other species have smooth leaves), and stiff black hairs up the stem.

Concerns Orange hawkweed is a great concern because of it ability to reproduce several ways.  The clusters of 5-30 flowers produce between 12 and 50 seeds per flower and these seeds remain viable in the soil for up to 7 years.  This plant can also spread or reproduce from stolons (above ground runners), of which it produces an average of 6 per year, rhizomes (underground horizontal roots), or adventitious root buds (buds on the roots that can develop into a new plant at any point).  Not only does it have the ability to spread in a variety of ways but it is also believed to be allelopathic (exudes toxic chemicals into the soil that suppress surrounding vegetation).  The combination of these abilities makes it a very aggressive species that can rapidly create large, dense monocultures pushing out not only native, beneficial vegetation but also established lawns.

Identification This perennial has a basal rosette with many hairy leaves and a leafless, hairy stem that can be up to 30 inches tall.  Each rosette is capable of producing 10-30 flower stems, each of which have 5-30 orange flowers that are arranged in a flat-topped cluster.  The flowers are bright orange to orange-red and dandelion-like in appearance, with square ended petals.

What can you do? Due to the extensive root system of orange hawkweed hand-pulling and digging-up large infestations is not an effective means of control.  Very small infestations may be controlled by these methods but care must be taken to remove all of the root system because even the smallest fragment can produce a new plant.  Mowing is not recommended because it actually encourages the growth of this plant.  There are several herbicides that are effective in controlling orange hawkweed and re-seeding is always recommended to fill in the areas where this plant was removed.  If you have any questions regarding orange hawkweed or any other weed call your local weed district.

Visit the MWCA Weed ID pages for additional information and pictures of orange hawkweed.

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.

Hoary alyssum–A weed to watch for on your property

Friday, August 20th, 2010


Dr. Jane Mangold, MSU Assistant Professor and Extension Invasive Plant Specialist, just published an article about a weed to keep an eye out for during the late summer.    The following is an excerpt from her article:

Have you noticed a small, white-flowered mustard growing prolifically in your neighborhood? It could be the noxious weed hoary alyssum (Berteroa incana). Hoary alyssum was added to the state noxious weed list in 2008, and may not be as familiar as other notables like spotted knapweed, Canada thistle or leafy spurge.

However, if you live in southwestern Montana, where this weed is most prevalent, you’ve probably seen it along a bike trail or road, in a waste area or pasture, or even in your yard. It flowers from spring through late fall, and is currently very noticeable as other vegetation begins to die back for the season.

Read the complete MSU news article here.

Visit the MWCA Weed ID pages for additional information and pictures of Hoary alyssum.

Weed of the Week – Blueweed

Thursday, August 12th, 2010


Blueweed - photo by Kellieanne Morris, Ravalli County MT Weed District

Blueweed - photo by Kellieanne Morris, Ravalli County MT Weed District


Blueweed or viper’s bugloss is native to Europe and has invaded much of the eastern U.S. and parts of the western U.S.  The first record of this plant in Montana was in 1916.  It was listed as a category 2 noxious weed on our state list in March of 2008.  Blueweed thrives in gravel bars along rivers and also does well in irrigated pastures.

Blueweed can be toxic to horses, sheep, and cattle.  The hairs that cover the plant may also act as a skin irritant for humans.  This plant can become quite large greatly reducing the productivity of grazable lands due to it being unpalatable.  It has the potential to ruin hay due to its high moisture content.  It also has the ability to destroy wildlife habitat and native plant biodiversity.  It reproduces by seeds that stick to clothing, animal fur, and feathers and may also be disperse by flowing water.  Each plant produces between 500 and 2000 seeds.

Blueweed is most easily identified by its bell shaped flowers that come in shades of blue, pink, and purple.  The flowers bloom a few at a time in a scorpoid raceme (resembles a scorpion’s tail).  Four or five, usually pink stamen stick out from the center of the bell shaped flowers.  Blueweed is a biennial, meaning that it lives for two years.  The first year that this plant emerges it is in the form of a rosette.  Second year plants typically bolt and produce flowers.  The stems are a grayish-green color and are covered with hairs and black dots.  The leaves are lance shaped and are also covered with hairs.  The plant can be anywhere from 5 inches to 3 feet in height.  From a distance it may resemble lupine.

What can you do?

This tap rooted plant can be hand pulled (with gloves and long sleeved shirts) or dug up with good results in small infestations.  Mowing can help to reduce the seed production if repeated throughout the growing season but is not a long term solution.  Herbicide is an effective control method when applied correctly.  Call your local weed district for recommendations on herbicides.  As always an integrated weed management plan utilizing all effective means of control and revegetation is the best option for reducing and eradicating blueweed.  If you have any questions about blueweed or any other noxious weeds call your local weed district.

Visit the MWCA Weed ID pages for additional information and pictures of blueweed.

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.

Weed of the Week – Yellowflag Iris

Thursday, August 5th, 2010


Yellowflag Iris Flower

Yellowflag Iris Flower


Yellowflag iris, native to Europe, Great Britain, North Africa, and the Mediterranean region can be found almost everywhere in the United States.  It is found in wetlands, along the edge of ponds, lakes, or slow moving streams or rivers and is fast becoming one of our most aggressive wetland bullies.  This plant can grow in full sun or part shade.  When it blooms in late spring to early summer it is unmistakable with its large pale to bright yellow iris flowers.  The flowers look very similar to a garden iris but they are often streaked with brown to purple lines.  Yellowflag is often mistaken for cattails when the blooms are not present.  The best way to distinguish this plant when flowers are not out is to look for the large fruit pod in the summer or the fan-shaped plant-base other times of the year.


Yellowflag is a popular wetland ornamental that is still sold on-line.  It is very easily spread downstream of its original location both by broken off pieces of rhizome (roots) and by floating seeds.  This plant forms incredibly dense stands connected by rhizomes.  Several hundred flowering plants can be connected in one rhizome mass.  These stands become so dense that they choke out all other native and beneficial wetland vegetation.  The dense rhizome masses trap sediment, which reduces water flow affecting fish, plants, and animals.  Yellowflag iris is toxic to livestock and other herbivores and the resins that it contains will cause skin irritation in humans.


This perennial has showy yellow flowers that resemble a typical garden iris.  Each stem may have several flowers that each have 3 large downward facing yellow sepals that are streaked with brown or purple lines and 3 upward facing yellow petals.  The plant including the flower stalk is 3-4 feet tall.  The leaves are mostly basal and are folded around the stem in a fan-like fashion.  The leaves will stay green until harsh winter weather begins.

What can you do?

Yellowflag iris is difficult to control both by mechanical means and with herbicide.  When hand pulling or digging make sure to wear gloves because of the irritating resins and also make sure to get all pieces of the rhizome mass.  One small fragment can start a new mass of plants.  To use herbicides on yellowflag an aquatic license is required because of its proximity to water.  If you have yellowflag iris on your property or you know where this plant can be found please contact your local county weed district.

Visit the MWCA Weed ID pages for additional information and pictures of  yellowflag iris.

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.

Are noxious weeds ranked or prioritized?

Monday, May 17th, 2010


In 2010 the Montana Department of Agriculture revamped the noxious weed priority system.   Noxious weeds are now rank one of 5 priorities.

Priority 1A – These weeds are not present in Montana.  Management criteria will require eradication of detected; education and prevention.

Priority 1B – These weeds are have limited presence in Montana.  Management criteria will require eradication or containment and education.

Priority 2A – These weeds are common in isolated areas of Montana.   Management criteria will required eradication or containment where less abundant.  Management shall be prioritized by local weed districts.

Priority 2B – These weeds are abundant in Montana and widespread in many counties.   Management criteria will require eradication or containment where less abundant.  Management shall be prioritized by local weed districts.

Priority 3 – Regulated Plants – NOT Montana Listed Noxious Weeds.  These regulated plants have the potential to have significant negative impacts.  These plants may not be intentionally spread or sold other than as a contaminant in agricultural products.  the state recommends research, education and prevention to minimize the spread of the regulated plant.

Download a copy of the current priority list of Montana Noxious Weeds.

Missoula County Success Against Yellow Flag Iris

Tuesday, February 16th, 2010


Bancroft Pond in 2006

Bancroft Pond in 2006

We tend to be a little unique here in Western Montana. Many of you know that here in Missoula we walk to the beat of a different drum, just stand on Higgins Ave. any day of the week and you will see people walking, literally to the beat of different drums! All joking aside, we have made great progress over here in terms of raising public awareness of noxious weeds and the importance of using an integrated approach to manage them. This is evident on City Open Space, County Parks and within our VMA’s. The Missoula Valley Yellowflag Iris Eradication Project is one project in particular that deserves attention and has been very successful at raising public awareness about controlling noxious weeds and has generated  overwhelming public support for stopping new invaders.

Until 2001 the bulk of the distribution of yellowflag iris (YFI) in the Missoula Valley was confined to a 1.5 mile section of lower Pattee Creek. In 2001 redevelopment of southwest Higgins Avenue involved updating drainage culverts and resulted in connecting lower Pattee Creek to the Bitterroot River through a series of drainage ditches and ponds. One consequence of altering the path of Pattee Creek was an explosion of YFI in these waterways. After reconstruction the YFI populations expanded to approximately 3.5 miles of drainage ditch between lower Pattee Creek and the Bitterroot River, and completely lined the Bancroft Ponds, a popular urban park. When the Missoula County Weed District mapped the extent of the YFI in order to get baseline data on the infestation, the discovery of several immature YFI where the ditch now drained into the Bitterroot River and this increased the severity of the problem. Land managers in this area recognized the need for immediate response to this problem; if the infestation remained unmanaged it would easily spread throughout the lower Bitterroot and Clark Fork rivers.

In 2004 a collaborative effort was undertaken by multiple partners in the Missoula Valley to begin to address these YFI infestations. The Missoula County Weed District, Missoula City Parks and Recreation, and the University of Montana launched an awareness campaign, targeting residents in the Pattee Creek area as well as the greater Missoula area. This campaign included newspaper articles, direct mailings, door-to-door visits and homeowner group meetings. The partners were pleasantly surprised, as once most residents where informed about the negative impacts YFI has on riparian habitats, they became very supportive of managing this invasive weed.

In 2005 the City of Missoula Parks and Recreation Department began chemical and mechanical control of YFI in Bancroft Ponds Park, home to the largest infestation of this plant in the valley. A commercial applicator sprayed the infestation with an 8% solution of aquatically labeled glyphosate and a team of interns mowed mature flowers for a ¼ mile upstream of this infestation to reduce seed input into the pond. The city continued these same controls on these infestations in 2006.

In the spring of 2006 Missoula County Weed District staff and a team of University of Montana interns went door to door in neighborhoods at the upstream end of the infestation handing out educational materials about YFI and the eradication campaign. In the spring of 2006 landowners in the Pattee Ck. Vegetation Management Area became involved with the project and a commercial applicator was hired to treat the upper ½ mile of the infestation; all of which was on private lands. Along this stretch of creek concentrated aquatic glyphosate was injected into flower stalks. This helped to eliminate the possibility of non-target damage to the many ornamental plantings landowners have established along the creek. In the fall of 2006 the University of Montana treated several infestations at a flood control pond within the project area.

In 2007, the project received a grant from Noxious Weed Trust Fund to treat the entire project area. This increase in funding for the project coupled with promising   results from 2005-06 controls for the first time partners felt confident that eradication of YFI in the Missoula Valley was actually achievable. The treatments have moved away from stem injection, to precision spot spraying with a backpack. Stem injection proved to be too labor intensive and not as effective as foliar application. The entire project area was treated again in 2008, with huge reductions in infestation size and frequency.  In 2009 we again received a grant from the Noxious Weed Trust Fund. In the 2009 field season some sites no longer need to be treated but where still monitored for seedling germination. In the past five years, we have observed as much as a 90% reduction in YFI across the project area, with complete eradication at many sites. Yearly monitoring of all areas will continued to assure no seedlings emerge as the seed viability of YFI isn’t well documented.

Bancroft Pond in 2009

Bancroft Pond in 2009

Each field season we maintain contact with our landowners and each year we are encouraged by the positive response from the landowners.  From the beginning of the project educating the public on the negative environmental impacts of noxious weeds and instilling a vision of attractive replacements for YFI was critical for getting support from a largely skeptical public. Partners (public and private) are now working on restoring the ponds and urban wetlands present in Bancroft Ponds Park, with the hopes that this site will serve as a restoration demonstration area. On Halloween of this year volunteers from across the project area held a planting day, where we planted Rocky Mountain Iris, Blue Camas, Yellow Monkey Flower and spread a native riparian seed mixture.

Call us what you want… Granola, Hippies, Freaks. But remember we are all in this battle together, working towards a common goal of protecting Montana from the invasion of noxious weeds. And bite your tongue because your kids may someday be going to school here and if they do, they may like it so much they never leave!