HPIPM:Dalmatian toadflax

Taxonomy

Domain	Eukarya
Kingdom	Plantae
Phylum	Magnoliophyta
Class	Magnoliopsida
Superorder	Asteranae
Order	Lamiales
Family	Plantaginaceae
Genus	Linaria

Scientific Name

Linaria dalmatica

Scientific Name Synonyms

Linaria dalmatica ssp. dalmatica

Linaria genistifolia ssp. dalmatica

Common Name

Dalmatian toadflax

Dalmatian toadflax (Linaria dalmatica)

Author: George Beck, Colorado State University Cooperative Extension

Adapted from the Colorado State University Extension Natural Resources Fact Sheet "Biology and Management of the Toadflaxes"

Identification and Life Cycle

Dalmatian toadflax (Linaria dalmatica) is a creeping perennial member of the figwort family (Scrophulariaceae). It differs from yellow toadflax principally in being larger and having differently shaped leaves. Flowers resemble those of cultivated snapdragon; each has a spur extending below from the lower lip of the corolla. They are about 1 inch long, bright yellow with a bearded, orange throat and occur in terminal, somewhat elongated clusters with the youngest flowers at the tip. Seeds are irregular in shape, angular, somewhat flattened, thin-edged, strongly netted, gray and 1/24 to 1/16 inch across. Clumps of stems are 3 to 4 feet tall. Waxy leaves are broad, ovate, sometimes heart shaped and upper leaves clasp the stem (an important difference). Dalmatian toadflax can form deep taproots and white, creeping rhizomes.

Habitats

Toadflax invasion is favored by disturbance, and invades degraded areas such as roadsides, abandoned lots and fields, gravel pits, clearings, and overgrazed rangeland.

Impacts

Dalmatian toadflax is an aggressive invader and displaces desirable plant species. Cattle generally avoid grazing the plant, and it can be poisonous to cattle if consumed in large quantities.

Biology and Ecology

Seedlings can emerge as early as early March. First year Dalmatian toadflax plants often produce prostrate shoots in fall that survive into the following spring. Mature Dalmatian toadflax may produce prostrate shoots, but to a lesser extent, and these typically die before winter and shoots emerge the following spring from roots. Dalmatian toadflax roots may grow 20 inches deep or more nine weeks after seedlings have emerged and have vegetative buds that give rise to new shoots. Patch expansion can be dramatic. Toadflax roots may penetrate the soil 4-10 feet and lateral roots may extend 10 feet from the parent plant. Dalmatian toadflax typically flowers beginning in late spring and may continue until fall, particularly if moisture is not limiting.

Management Approaches

All toadflax species are very difficult to control, and management plans should integrate as many strategies as possible to increase potential for success. Assess the condition and composition of the existing plant community in an infested area then determine the approximate composition of the desired plant community needed to achieve land management goals and objectives. Create a management plan that combines various control strategies to foster development of the desired plant community.

Biological Control

Several classical biological control agents are available to use against toadflaxes. However, the success of these agents remains largely unknown. The flower beetle (Brachypterolus pulicarius), a defoliating moth (Calophasia lunula), two seed capsule feeding weevils (Rhinusa antirrhini and R. neta), a stem-boring weevil (Mecinus janthinus), and a root-boring moth (Eteobalea intermediella) have been released in the U.S. to control all toadflax species. These species may help to control shoots and seed production as well as decrease root vigor, but data are unavailable to document their effects.

Mechanical and Cultural Control

Mechanical methods such as mowing and burning are not effective for reducing Dalmatian toadflax due to its ability to regenerate from an extensive root system. Cattle, sheep, and goats will eat Dalmatian toadflax, but it is not preferred.

Chemical Control

Herbicide applications on fall regrowth or in spring before flowering are most effective in controlling Dalmatian toadflax.

Examples of herbicides that can be used to manage Dalmatian toadflax

Consult herbicide labels for additional rate, application, and safety information. Additional herbicide information can be found at http://www.greenbook.net.

Due to constantly changing labels, laws and regulations, the sponsors of this web site assume no liability for the suggested use of any chemicals noted in the management section. Contact your local pest management personnel for current information on labeled pesticides that can be used for the intended plant disease, insect pest or weed.

References

For more information and images please visit IPM Bugwood. http://www.ipmimages.org/search/action.cfm?q=Dalmatian%20toadflax