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

Leafy Spurge

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.

MSU June Post – Biological Control

Saturday, June 30th, 2012


Biological control is a term often used to describe insects that help to control noxious weeds.   The June MSU Monthly Weed Post provides updated information about some of the agents currently available for leafy spurge, spotted knapweed, dalmatian toadflax and houndstonge.

Download the June 2012 Monthly Weed Post from Montana State University.

Visit the MWCA Biological Weed Control page for more information.  Contact your local weed coordinator for help getting biocontrol agents in your area.

2010 Statewide Biological Control Monitoring Report

Thursday, October 21st, 2010


APHIS-PPQ completes a second season of the statewide biological control monitoring program in cooperation with Montana Dept. of Ag. and the BLM. Over the past two years, this project has been helping counties, state and federal agencies, and Indian Reservations with monitoring past biological control releases and assessing the potential for collectibility when they find established populations.  Download your copy of  the report for the work completed in 2010.

Weed of the Week Series – Leafy Spurge

Thursday, July 8th, 2010



Leafy Spurge was introduced as an ornamental into the United States in the 1800’s.  Presently, leafy spurge covers over 3 million acres in 29 states.  It is having major economic and ecological impacts on many western states.  These impacts are related to its affect on grazing, wildlife habitat, wildlife related recreation, native plant populations, and ecosystem biodiversity.


Leafy spurge is extremely aggressive and can out-compete native vegetation creating monocultures.  The milky sap emitted from the stem of leafy spurge is poisonous to humans, horses, and cattle.  There are cases where this sap has killed livestock and resulted in blindness in humans.  Like livestock, wildlife also avoids grazing spruge.  The abundance of leafy spurge in areas historically grazed by wildlife has caused them to migrate into areas they have not before inhabited.

Leafy spurge is having an enormous economic impact on the western states.  Montana, North and South Dakota, and Wyoming together spend approximately $144 million per year on leafy spurge control.  Land that has been invaded with leafy spurge has a decreased market value because of the plants detrimental ecological effects, as well as, the costs associated with control.


Leafy spurge has small, inconspicuous green flowers that are surrounded by a pair of yellow-green heart shaped leaves.  These leaves are often mistaken for the flower itself. This plant can grow up to 3 feet tall and when the stem is broken milky white sap seeps from it.  The leaves that attach to the stem also seep white sap when damaged.  These leaves are long and arranged alternately along the stem.  The taproot of leafy spurge can be up to 30 feet deep.  The seed head on this plant explodes when it is dry, sending the seed up to 15 feet from the mother plant.

What can you do?

Leafy spurge is an aggressive competitor and it takes aggressive management to gain control of infestations.  The most successful means of control of leafy spurge have been an intergraded weed management plan that utilizes a combination of methods.  There are five methods of controlling leafy spurge, they include:  prevention, hand-pulling, biological, revegetation, grazing, and chemical.  Prevent infestations by using weed and weed seed free hay, mulch, and gravel.  It is also important to prevent the transportation of seeds and root particles on vehicles or clothing.  Eradicate small outbreaks as soon as possible.  Hand pulling spurge is not the most efficient method, but it can be effective on plants that are in their first year of growth.  There are biological controls that have been found to be effective in Montana.  They are the flea beetles (Apthona) and root/stem boring beetles (Oberea erythrocephala).  Sheep and goat grazing can also be a useful tool when timed correctly and supervised by a knowledgeable herder.  Revegetation with competitive plants is always important with any weed control program.  All leafy spurge outbreaks take patience and attentiveness to overcome.  Have any questions?  Call your local county weed district.

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

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.

Bear Trap Success Story

Wednesday, June 23rd, 2010


In April of 2001 a float trip down the Madison River was conducted involving members of the BLM, the Montana Wilderness society, Madison County, U.S. Forest Service, the Greater Yellowstone Coalition, Gallatin County and other interested individuals. They determined that due to the size, density and location of the current infestations, that eradication was no longer an option but that a long term plan of control and containment would be more practical and cost effective. With members of the original group plus a Dow AgroSciences representative and others knowledgeable in noxious weed control a second float trip was conducted in August to help devise a plan of action.

Weed control was initiated in the fall of 2001 using both biological agents and herbicide. The biological control was released in the more inaccessible areas above the river and above the hiking trails, while herbicide was used along the trails and from the trails to the river, where public use is the highest. Herbicide application was done as a joint effort between the BLM and the Madison County Weed Board with joint spray days being held twice yearly, one in the spring and the other in the fall. After the first year of treatment we were surprised at how the native grasses came back and became fairly competitive with the knapweed. In 2002, 2003, and 2004 a private contractor treated the road leading into the trailhead and any of the trails that couldn’t be covered during the joint spray days. Starting in 2005 the BLM hired a crew of two sprayers that would take over the role of the private contractor. A minimum of three float trips a year were scheduled in order to gain access to some infestations of Leafy Spurge that are inaccessible by land.

To date the project has met with great success. The size and density of the noxious weed infestations has been reduced dramatically with the only problem being the re-infestation of some of the treated areas by cheatgrass. Beginning in 2010 we hope to get the original group together again to determine what our strategy for the next ten years will be and how we will handle the re-vegetation of some of the areas infested by cheatgrass.

Canal Success in Valley County

Wednesday, June 9th, 2010


Leafy spurge is along fenceline and in the pasture

Leafy spurge is along fenceline and in the pasture

The Valley County Weed District has teamed up with the Glasgow Irrigation District since 2002 to control noxious weeds on 46 miles of main canal and 44 miles of lateral canals. Think about noxious weed seeds being spread by a water system 90 miles long. Wildlife and domestic animals have been spreading seeds from near that water source. Also, think about walking through a solid stand of mature Canada thistle for 1/8 mile! Not a pleasant thought! That was the situation in 2002 on the irrigation canal system in Valley County. The Glasgow Irrigation District and the Valley County Weed District decided to do something about these noxious weeds. Now in 2009, they are under control and the canal system, overall, is in good condition, thanks to financial funding through the Montana Noxious Weed Trust Fund Grant Program. The canal system has 46 miles of main canal from Vandalia Dam in the west and flows east to Nashua. There are 19 lateral canals (44 total miles) that also were infested in areas with leafy spurge that are under control. For anyone who has ever been involved with noxious weed control, the reality is that the work is never truly done. However the ranchers and farmers who use the canal system have seen great results and can be confident that their land and crops will not be lost or severely damaged by infestations of noxious weeds.

Leafy spurge was treated with Tordon22K and 2-4D

Leafy spurge was treated with Tordon22K and 2-4D

For more information contact Rick Stellflug, Valley County Weed Coordinator

Leafy Spurge: Biology, Ecology and Management

Monday, March 15th, 2010


Authors: Kim Goodwin, Roger Sheley, Robert Nowierski and Rodney Lym

Summary: Identification, life cycle, distribution, physical control, plant competition, grazing management, biological and chemical control, suggested management plan. 25 pages. 12 color photos, distribution map for U.S. and southern Canada, tables, graphs and appendix detailing habitat requirement, biology and collecting suggestions for currently approved insect biocontrol agents.

Click to download load this publication for Montana State University Extension publications.