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

Priority 1B weed

Scotch Broom MSU Monthly Weed Post

Thursday, May 12th, 2011


Scotch Broom  is the latest plant featured in the MSU publication on noxious weeds.   This weed is only known to exist in two counties currently.  Download and read this informative publication and be on the lookout for it in your neck of the woods.

Visit the MWCA Weed ID page for details about scotch broom. Contact your local weed coordinator if you think you find it in your area.

Knotweed Complex: MSU February Monthly Weed Post

Thursday, February 10th, 2011


The knotweed complex  is featured in the February monthly post from MSU publication on noxious weeds.  This complex includes the Japanese Knotweed, Giant Knotweed and the Himalayan Knotweed.  Download and read this informative publication. This weed is currently found in 13 counties currently. Visit the MWCA Weed ID page for details about the weed and were it is known to exist. Contact your local weed coordinator if you think you find it in your area.

Eurasian Watermilfoil Featured in New MSU Publication

Monday, February 7th, 2011


MSU and the Statewide Noxious Weed Awareness and Education Campaign are teaming up to bring you a Monthly Weed Post.     This post is a monthly two-page article available for download feature a different weed.  It will have the latest information on the weed.

January’s Monthly Weed Post features Eurasian Watermilfoil.  Did you know in 2010 that EWM was found in six additional counties.   Download the monthly post and in just a few minutes be up to date on EWM.

Weed of the Week – Rush Skeltonweed

Thursday, November 4th, 2010


Rush skeletonweed was accidentally introduced in the U.S. in the early 1900’s.  It was first discovered in Spokane, Washington in 1938.  Today, Idaho and Washington have serious infestations of this weed.  In Montana, Lincoln and Sanders Counties are battling sizable infestations.  The Montana Department of Agriculture has spent around $500,000 trying to control Rush skeletonweed in these counties.  It is extremely important for this plant to be located and eradicated before it is capable of spreading.

Concerns Rush skeletonweed is a very difficult plant to control and it spreads very easily.  Seeds of this plant have been documented to travel up to 20 miles from the original plant via wind. The taproot of this weed can be 7 feet long and the roots can also spread laterally.  These lateral roots and root fragments can start new plants.  It also out competes native vegetation and creates poor wildlife habitat.

Identification The bright yellow flowers of this plant are found in clusters of 2-5 blooms.  The sharp toothed leaves, which are similar to those of a dandelion, only occur at the base of the plant.  The stems of this plant are completely leafless but the base of the stem is covered with downward facing, coarse, brown hairs.  When this plant is broken off a milky substance will ooze out.  This long-lived perennial can grow to be up to 4 ft tall and can produce up to 20,000 seeds at a time. 

What can you do? Large infestations of Rush skeletonweed are just over the border in neighboring states.  It is very important to take measures to prevent the spread of this weed into our county.  These seeds can be spread by traveling through infested areas and transported on vehicles, machinery, clothing and animals.  Prevention and immediate eradication is the goal for managing Rush skeletonweed.  Small infestations can be controlled by hand-pulling and digging, done diligently throughout the year and for up to 10 years.  Pulled plants should be burned to destroy the seeds and root system.  Mowing is ineffective because it will not sufficiently stress the plant.  Tillage will not work; it will spread the plant further.  There are several chemicals that are recommended for the control of Rush skeletonweed and for a list of these call your local weed district. There are three biological controls used on Rush skeletonweed and the most wide spread is a gall midge; this midge reduces seed production and deforms the plant.   If you have any questions about Rush skeletonweed please do not hesitate to contact us.

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

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

NRCS Publishes New Information for Scotch Broom

Thursday, October 28th, 2010


Natural Resource Conservation Service has published a series of technical notes on Montana’s invasive species.   These publications are a great resource including line drawings, photographs of plants at various stages of growth and details that will help you further identify and understand management alternatives.

The most recent invasive plant featured is Scotch Broom.   This publication was issued in September 2010 and is ready for download.

Weed of the Week – Eurasian Water Milfoil

Thursday, October 21st, 2010


Milfoil is native to Europe and Asia, but was introduced to the United States between the late 1800’s and the 1940’s.  It was collected from a lake near Seattle in 1965 and has since been found in many lakes in that area.  This plant is primary spread from lake to lake by boats and trailers, with some spread by water birds.  It is very difficult to control and unfortunately has recently been found in Montana.  There are multiple species of milfoil, which are very difficult to distinguish amongst.  Some of these species are native to Montana.  Plant experts often rely on DNA to distinguish between species.  The noxious species tends to have its leaflets closer together than the native species.   

 Concerns  Milfoil forms very dense mats of vegetation on the surface of water, which drastically changes the ecology of the body of water.  It interferes with recreational water activities such as swimming, water skiing, boating, and fishing.  The mass of vegetation created by this plant can cause flooding and it creates good habitat for mosquitoes.  Milfoil starts growing earlier in the season than most native aquatic plants and therefore shades the majority of them out.  This has negative impacts on fish and wildlife habitat.  This aquatic invader can also invade fish spawning habitat, clog irrigation intake pipes, and can hinder power generators.  It has the ability to reproduce through broken off plant parts at a very rapid rate and can take over an entire lake in 2 years.  Once milfoil is established it is difficult if not impossible to eradicate.  

Identification  Milfoil species are easy to identify as a group because they all have feather-like leaves arranged in whorls around the stem.  Identifying individual species is not quite as simple.  It is so difficult that for many years Eurasian water milfoil and northern milfoil were classified as the same species.  There are a few characteristics that help in separating the noxious from the natives but they cannot always be relied upon.  Eurasian milfoil typically has twelve or more pairs of leaflets on each leaf, the leaves tend to collapse around the stem when removed from the water, and the mature leaves are typically arranged in whorls of four around the stem.

What can you do?  Preventing the spread of this weed is the most important thing we can do at this point.  Pick every fragment off of your boat or trailer and put them in a garbage can.  If you see plant fragments on someone else’s boat or trailer tell them about the threat that milfoil possesses.  Spreading the word is so important because an entire lake can be infested by just one tiny fragment.  Once a lake or river becomes infested there is no way to completely eradicate the invader.  Herbicide treatments, diver harvesting or hand pulling (containing all fragments), underwater rototilling, and instillation of bottom barriers are all somewhat successful in controlling the growth of milfoil.  If you are interested in helping stop the spread of Eurasian water milfoil learn how to identify and safely remove it, get other people involved in the prevention, and report any aquatic vegetation that you suspect could be the noxious species.  If you have any questions about Eurasian watermilfoil or any other plant call your local county weed district.

Visit the MWCA Weed ID pages for additional information and pictures of Eurasian Water Milfoil.

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 – Purple Loosestrife

Thursday, October 14th, 2010


This beautiful riparian plant was introduced as an ornamental from Europe in the 1800’s. It was first reported to be a problem weed in the 1940’s.  Purple loosestrife is established in nearly every state in the U.S.  Purple loosestrife lives in moist, marshy sites.  It will inhibit streams, rivers banks, bogs, irrigation canals, lakesides, and drainage ditches.

Concerns Though this plant is very beautiful it is very problematic for aquatic habitats.  Purple loosestrife chokes out native vegetation and creates narrow waterways.  The narrowing of waterways increases stream sedimentation and this can negatively affect fish habitat.  This weed also negatively impacts waterfowl habitat by degrading nesting sites.  Purple loosestrife can easily spread by seed dispersal.  A single purple loosestrife plant can produce up to 2.5 million seeds annually.

Identification Purple loosestrife is 4-7 feet tall and can produce many stems per plant.  The flowers are a rose-purple color and are clustered along the stem.  The flowering stem is spike-like and resembles a lupine panicle.  The stems are square to octagonal.  The long, narrow leaves come off the stem oppositely.  This plant is sometimes confused with native fireweed.

What can you do? Prevention is the most important tool in the fight against the spread of purple loosestrife.  Prevent disturbances in wetland areas because this is where purple loosestrife thrives.  It is important that purple loosestrife plants be detected early before they are able to spread out of control.  Cutting is relatively ineffective, it will decrease the spread of seeds but will not kill the plant.  Hand pulling can be done on small patches and is mildly successful.  Reseeding should occur after a treatment.  A biological control does exist for large infestations.  There are leaf-eating beetles and root-mining larvae that are known to help reduce the outbreak of purple loosestrife.  The most efficient method is herbicide application.  Herbicide application on this weed should be used with extreme caution due to the plants proximity to water sources.  For more information and guidance on your weed issues call your local weed district.

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

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.

Curly-leaf Pond Weed Found in Montana!

Tuesday, July 13th, 2010


In late June, curly-leaf pondweed (Potamogeton crispus), one of Montana’s Priority 1 noxious weeds, was found near Bozeman in several ponds along the East Gallatin River drainage system. Priority 1 noxious weeds have limited presence in the state, and require eradication or containment where they are present, with prevention encouraged in areas not yet infested.

Melissa Graves, Plant Identification Diagnostician from Montana State University’s Schutter Diagnostic Lab, gave a full description of the invasive aquatic plant that occurs in ponds, lakes, and slower moving streams or rivers.

“Curly-leaf pondweed prefers shallow water depths with a silty, high-nutrient bottom. It is distinguished from native pondweed species by its growth habit and distinctive leaf edges. Unlike native pondweeds, it actively grows in winter, with new plants emerging in spring. The leaves have wavy edges resembling lasagna noodles. They are about one to three inches long, narrow, reddish in color, and translucent, with flattened stems visible through the leaves.”

Read the complete article from MSU News Service here.

Visit the MWCA curly leaf pondweed identification page.

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.