Montana Weed Control Association

Introduction

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.

Concerns

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.

Identification

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.