Linaria dalmatica  • Class B

Dalmatian toadflax is a short-lived perennial herb that grows from 2.5 to 5 feet tall.

It‘s waxy, light green, alternate leaves are heart shaped and clasp the woody branching stems.

It blooms from May to August. Flowers are bright yellow, tinged with orange in the center and closely resembles a snapdragon flower. The petals have 2 lips.  The upper petals have 2 lobes and the lower has 3 lobes.

The root system may be as deep as six feet and may spread laterally as much as ten feet. 

Mature plants are strong competitors against native plants and other desirable species. It is a prolific seed producer and contains a poisonous glucoside which is toxic to livestock. 

The plant grows along roadsides, in pastures, idle land, and rangeland, particularly in sites with coarse-textured soils. Its extensive root system allows the plant to survive in adverse soils and climatic conditions. 

D.T. seedlings are poor competitors for soil moisture against established plants, but once established they become extremely competitive and will significantly affect the surrounding vegetation. 

A mature plant can produce up to 500,000 seeds a year which are primarily dispersed by wind. 

• Preventing the establishment of populations of Dalmatian toadflax is the most time and cost effective way of controlling this species. Plants are easiest to control in the seedling stage and when found should be removed immediately. 

• Pulling small infestations before they become established can be an effective control method, especially if growing in sandy or moist soil. 

• The toadflax stem weevil, Mecinus janthinus is a biocontrol agent used in Washington State to control Dalmatian toadflax. For information about the biological control of this or any other noxious weed, see the WSU Extension Integrated Weed Control Project ..  

• Spot spraying with an herbicide containing the active ingredient Glyphosate may be used effectively while the plant is actively growing, repeat as needed. Be aware, Glyphosate is non-selective and will injure any plants that it comes in contact with, including grass. 

• Another option would be an herbicide containing the active ingredient Imazapyr. Treatment in mid-fall when plants are dormant, has been shown to provide excellent control.  

• When using herbicides, read and follow all label instructions and obey all label precautions. 

• To minimize any harmful impact on bees and other pollinators, timing is important.  Ideally, treat plants before blooming.  If treatment after blooming is necessary, do control work early in the morning, or in the evening when bees are less active.

For more information on this noxious weed Download our Flyer or visit Washington State Noxious Weed Control Board Here.  Photos by Rebecca Shoemaker, Pierce County Noxious Weed Control Board.