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

Yellow Toadflax

Importance of Matching your Bug to Your Toadflax

Thursday, May 15th, 2014


It is critical that the appropriate stem-boring weevil be utilized on the specific species of toadflax you are trying to control. Presently, the only reliable way to distinguish Mecinus janthinus(for yellow toadfax) and M. janthiniformis (for Dalmatian toadflax) appears to be the host plant on which they were collected. Please discuss with your supplier to ensure the agents you receive were collected from the same species of toadflax for which you plan to release them. Morphological differences of the weevils are very subtle and may not be reliable.

Biological Control Agents

The stem-mining weevil Mecinus janthinus was released in the US and Canada as a biological control agent of Dalmatian and yellow toadflax. Recent research has shown that rather than a single Mecinus species, there are two host-specific Mecinus weevils that utilize weedy toadflaxes. These are:

• Mecinus janthinus, which utilizes yellow toadflax, and,

• Mecinus janthiniformis, which utilizes Dalmatian toadflax.

Both weevils have apparently been released and established in the U.S. Choosing the appropriate host-specific weevil should increase the efficacy of biological control of both Dalmatian and yellow toadflax.

Dalmatian and Yellow Toadflax (Linariadalmatica and L. vulgaris)Identification:

Dalmatian and yellow (or common) toadflax are members of the Plantaginaceae (plantain) family, and are easily recognized by their snapdragon-like yellow flowers (right) with a single long spur. Flowers can bloom from early summer until killing frost.

• Dalmatian toadflax ranges in height from 15-60 inches with broad, fleshy and heart-shaped leaves which clasp the stem.

• Yellow toadflax is shorter, from 7-32 Inches tall with leaves that are long, linear and noticeably less succulent

Visit the weed identification pages for yellow toadflax and dalmatian toadflax for more information on these two weeds.

Dalmatian toadflax is on the left and Yellow toadflax on the rigth

Dalmatian toadflax is on the left and Yellow toadflax on the right

Please contact your local county weed coordinator or Gary D. Adams, State Plant Health Director at USDA, APHIS, PPQ if you have questions.

MSU Report for the Montana Noxious Weed Trust Fund Advisory Council

Wednesday, June 19th, 2013


This report for the Montana Noxious Weed Management Advisory Council was assembled in compliance with the Montana Noxious Weed Trust Fund Act and Administrative Rules which require an annual report from the Montana Agricultural Experiment Station and Montana State University Extension Service on current projects and future plans. This report is a compilation of major weed science research and education activities conducted by MSU over the past three years and includes highlights of funded Montana Noxious Weed Trust Fund grants as well as comprehensive reporting of all weed science research products and education funding and activities.

Montana Noxious Weed Trust Fund Projects 2010–2012

  • Biological Control of Common Tansy and Oxeye Daisy, Jeff Littlefield
  • Biological Control of Invasive Hawkweed and Tansy Ragwort, Jeff Littlefield
  • Biological Control of Russian Knapweed, Jeff Littlefield
  • Biological Control of Whitetop and Perennial Pepperweed,Jeff Littlefield
  • Can Biological Control and Targeted Sheep Grazing be Integrated to Suppress Spotted Knapweed?, Jeff Mosley
  • Cheatgrass Ecology and Integrated Management, Jane Mangold
  • Continental Divide Invasive Weed Barrier Zone, Kim Goodwin
  • Establishing and Monitoring Insectaries for Yellow Toadflax Biocontrol, David Weaver
  • Herbicide Resistance Extension Information for Montana Producers, William Dyer
  • Identifying and Testing Candidate Agents for Russian Olive Biocontrol, David Weaver
  • Implementing EDRR in Montana Using the INVADERS Database, Jane Mangold
  • Integration of Pathogens, Sheep, and Herbicides to Manage Cheatgrass, Fabian Menalled
  • Missouri River Watershed Coalition Coordination, Elizabeth Galli-Noble
  • Rangeland Revegetation Revisited, Jane Mangold        Saltcedar Effects on Mycorrhizal Fungal Communities and Screening of Native Species for Restoration, Erik Lehnhoff
  • Tall Buttercup Ecology and Integrated Management, Jane Mangold
  • Weed Free Borders Protection Program, Kim Goodwin
  • Weed Management Certification Program, Jane Mangold
  • Weed Seedling Identification Guide, Jane Mangold

Download a copy of the complete report 2013 MSU Annual Report to the MNWTF

Toadflax – MSU November Weed Post

Thursday, November 29th, 2012


This month MSU is  featuring Dalmatian and yellow toadflax, including information on their hybridization.  Didn’t know they could hybridize???  Well, then there is definitely something new for you in this month’s post from Montana State University.  Download the  November 2012 MSU Weed Post on toadflax.

Visit the MWCA Weed ID page for details about Dalmatian Toadflax and Yellow Toadflax.  Contact your local weed coordinator if you think you find it in your area.

MSU Research updates

Thursday, April 12th, 2012


MSU has published a weed research update.   It includes information on the following:

  • Mechanisms driving nonnative plant-mediated changes in small mammal populations and communities
  • Wild Oat Herbicide Resistance
  • Russian olive removal and revegetation
  • Impacts of saltcedar on ecosystems in Montana
  • Sulfur cinquefoil life history in northwest Montana
  • Vegetation surveys to quantify weed threats
  • Toadflax research
  • Common tansy control in natural areas

Download the MSU April 2012 Monthly Weed Post for complete details.

Assessing Environmental Risks for Established Invasive Weeds: Dalmatian (Linaria dalmatica) and Yellow (L. vulgaris) Toadflax in North America

Tuesday, July 26th, 2011


Abstract: Environmental risk assessments characterizing potential environmental impacts of exotic weeds are more abundant and comprehensive for potential or new invaders than for widespread and well-established species such as Dalmatian (Linaria dalmatica [L.] Mill.) and yellow (L. vulgaris Mill.) toadflax. Specific effects evaluated in our assessment of environmental risks posed by yellow and Dalmatian toadflax included competitive displacement of other plant species, reservoirs of plant disease, animal and insect use, animal toxicity, human toxicity and allergenicity, erosion, and wildfire. Effect and exposure uncertainties for potential impacts of toadflax on human and ecological receptors were rated. Using publicly available information we were able to characterize ecological and human health impacts associated with toadflax, and to identify specific data gaps contributing to a high uncertainty of risk. Evidence supporting perceived negative environmental impacts of invasive toadflax was scarce.

Authors: Sing, Sharlene E.; Peterson, Robert K. D.

Download and read the complete report.

Weed of the Week – Yellow Toadflax

Thursday, September 2nd, 2010



Yellow toadflax also known as butter-and-eggs or common toadflax was introduced into North America as an ornamental in the mid 1800’s.  Yellow toadflax has a long history of medicinal uses in Eurasia.  The Mennonites cultivated toadflax for dying homespun garments.  Yellow toadflax has spread throughout North America and is found mostly in the northeast and Pacific Coast region.  In 1973, Alberta, Canada designated yellow toadflax to be “the most troublesome perennial broad-leaved weed in Alberta”.


Yellow toadflax is very difficult to remove once the plant has been established because of its ability to adapt to a variety of sites.  It also has the ability to reproduce both by seeds and by vegetative roots.  This weed will displace desirable grasses and vegetation, which can lead to decreased carrying capacity on rangelands.  Yellow toadflax is also said to be mildly poisonous to livestock, though it is generally not palatable to livestock.  This tall bunch like weed will shade out vegetation from growing below it and therefore increasing topsoil’s exposure to erosion.


Yellow toadflax can grow from 8-24 inches tall.  The leaves of this weed are gray-green in color and are long and narrow.  They are also arranged alternately on the stem.  Though the leaves of the toadflax looks like leafy spurge, toadflax does not produce a milky sap.  The flowers of a yellow toadflax plant resemble those of a snapdragon with flowers that are 1-1¼ inches long and mostly yellow petals that have an orange throat and a downward pointing spur.  They are densely clustered at the top of the stem.  Yellow toadflax will bloom between June and July.  Each plant can produce up to 8,700 seeds.

What can you do?

The seedlings of Yellow toadflax are poor competitors for soil moisture.  It is important to keep a healthy community of grasses and other desirable species to prevent seedlings from establishing.  Hand-pulling and digging are useful tools on young plants and small infestation but these methods must be repeated on a long-term scale (10-15 years) to achieve complete control.  There are herbicides that have been proven to be useful in combination with mechanical methods and a proper grazing regime.  For herbicide recommendations or any other weed questions contact your local county weed district.

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

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.