Dalmation Toadflax 
(Linaria dalmatica)

Click on the photo to enlarge (Photo maybe used for non-profit uses with attribution to Mesa County Division of Pest Management).

County Management Strategy: Suppression on Mormon Mesa, Parker Basin and Big Creek. Eradication elsewhere in the County.

Identification: A perennial plant growing 1-3 feet tall with showy, yellow snapdragon-like flowers. Leaves are very waxy, heart shaped and the upper leaves clasp the stem. Flowers arise in the axils of the leaves and have a yellow spur and fuzzy orange throat. Seed production is very high.

Other names: None

Similar Species: Many ornamental snapdragons look like toadflax, since it is in the same family. Narrow leaved Dalmatian toadflax has similar flowers but linear leaves. Yellow toadflax has linear leaves, paler flowers and linear leaves.

Control Timing: During summer when flowerheads are first appearing; in the fall when at least 25% of stems are turning yellow.

Control Target: Prevent seed production and stress root system.

Control Methods: Repeated hand grubbing can be effective for small infestations. Large infestations require herbicide use and competitive planting. A surfactant or adjuvant must be added to the herbicide mix to break through the waxy leaf surface. Several biocontrol agents are available but need large infestations and a long establishment time. This is a difficult weed to control via any method. CSU Extension Service Fact Sheet No. 3.114 has more details on control of Dalmatian and yellow toadflax.

Status in Mesa County: Found in high numbers on Mormon Mesa near Molina, in Parker Basin and along Big Creek south of Collbran and on nearby road rights-of-way. A few plants have been found and eradicated on I-70 from the Grand Mesa exit to the Utah State line. A small infestation exists on Glade Park but is being treated and does not appear to be spreading. REPORT INFESTATIONS TO THE DIVISION OF PEST MANAGEMENT!

Photos:
http://www.invasive.org/species/subject.cfm?sub=5939

Fact sheets and control:
http://www.colorado.gov/cs/Satellite?c=Page&cid=1178305507375&pagename=Agriculture-Main%2FCDAGLayout

Additional Links:
http://www.nwcb.wa.gov/weed_info/Linaria_dalmatica.html
http://plants.usda.gov/java/profile?symbol=LIDA