Yellow Toadflax

Scientific name: Linaria vulgaris

Identification and Impacts

Yellow toadflax (Linaria vulgaris) is a perennial escaped ornamental plant that is native to the Mediterranean region. The leaves are narrow, linear, and 1 to 2 inches long. The stems are woody at the base and smooth toward the top. Sparingly branched and 1 to 3 feet tall. The showy snapdragon-like flowers are bright yellow with a deep orange center and have a spur as long as the entire flower. It develops an extensive root system, making control options varied. Yellow toadflax displaces desirable plant communities reducing ecological diversity and rangeland value. Decreases forage for domestic livestock, some big game species and decreases habitat for associated animal communities. The plant is known to be mildly poisonous to cattle. Goats and sheep have been known to graze the plants with little effect.

Habitats for Yellow toadflax include roadsides, vacant lots, gravel pits, fields, waste areas, other disturbed sites and rangeland. It has adapted to a variety of site conditions, from moist to dry and does well in all types of soil. The plant can even establish in areas of excellent condition in natural disturbances or small openings.

The key to effective control of Yellow toadflax is prevention and integrating as many management strategies as possible. Prevention is
always desirable when dealing with Yellow toadflax. Early detection and eradication can keep populations from exploding, making more management options available. With the plants varying genetically using many different approaches is important such as; herbicide, mechanical, cultural and biological methods. Details on the back of this sheet can help to create a management plan compatible with your site ecology.

Yellow toadflax is designated as a “List B” species in the Colorado Noxious Weed Act. It is required to be either eradicated, contained, or suppressed depending on the local infestations. For more information visit www.colorado.gov/ag/weeds and click on the Noxious
Weed Management Program or call Douglas County Weed Management at 303.660.7480.

Integrated Weed Management recommendations

Cultural -
Establish select grasses and forbs
as an effective cultural control
of Yellow toadflax. Contact
your local Natural Resources
Conservation Service for seed mix
recommendations. Bareground is
prime habitat for weed invasions,
so maintain healthy pastures and
prevent bare spots caused by
overgrazing.

Biological -
Calophasia lunula, a predatory
noctuid moth, feeds on leaves
and flowers of Yellow toadflax.
Eteobalea intermediella, a root
boring moth and Mecinus janthinus
a stem boring weevil are also
available. For more information,
contact the Colorado Department of
Agriculture’s Insectary in Palisade,
Colorado at 970.464.7916.

Mechanical -
Handpulling or digging is not
recommended for eradication
of Yellow toadflax because it’s
unlikely that the entire root will be
excavated and a new plant is likely
to occur. A single new plant might
be an exception. Tillage is not
recommended due to the creeping
root system.

Herbicides

NOTE: The following are recommendations for herbicides that can be applied to range and pasturelands.
Rates are approximate and based on equipment with an output of 30 gallons per acre. Always
read, understand, and follow the label directions. The herbicide label is the LAW!

HERBICIDE RATE APPLICATION TIMING
Chlorsulfuron (Telar – general
use)
Apply 1-3 oz/A product plus 0.50% v/v MSO Silicone Blend surfactant (multiple brands available) Apply at mid-flowering through fall. Telar has grazing restrictions above 1 1/3 oz/A rate. Please refer
to the label for more detail.
Picloram + Chlorsulfuron
(Tordon 22K – *restricted use* + Telar – general use)
Apply at 1 qt/Acre Picloram +
1.25 oz/A Telar plus 0.25% v/v
non-ionic surfactant.
Apply at flowering through fall. Typically late August through
September application timing has shown best results. Re-treatment
may be necessary. Refer to label for grazing restrictions on Telar.
Picloram (Tordon 22K – *restricted
use*)
Apply at 1.5 qt/A
plus 0.25% v/v non-ionic
surfactant or 1 qt/A rop oil concentrate
Apply in fall (late August through September). Re-treatment may be
necessary.

Online Services:

Weed Management

Public Works Operations Division

3030 North Industrial Way
P.O. Box 1390
Castle Rock, CO 80109
Phone: 303.660.7480
Fax: 303.814.3319
noxweeds@douglas.co.us

Office Hours

8:00 a.m. - 5:00 p.m.