Dalmatian toadflax was introduced into the west coast of the United States in the late 1800’s. It was brought here from the Mediterranean region as an ornamental plant. It has escaped captivity and now infests much of the northwestern United States. Unfortunately, this weed is still sold in greenhouses as Wild Snapdragon, Butter and Eggs, or Jacob’s Ladder. Dalmatian toadflax was first discovered in south-central Montana in the 1940’s. This weed has been reported in 43 counties throughout the state.
Concerns Dalmatian toadflax is a great concern because it will displace native vegetation and consequently displace animals associated with native vegetation. This weed is extremely successful at displacing native vegetation because it spreads both rhizomatously (roots that run parallel to the ground surface) and by seed. One plant can produce 500,000 seed per year. The loss of native vegetation will also increase soil erosion, sediment yield, and surface runoff due to loss of bunch grasses and sod-forming grasses.
Cattle ranchers are seeing lower carrying capacity on infested sites. Land that has Dalmatian toadflax can have lower appraisal value because of the cost of controlling it and the negative impact the weed has on the land.
Identification Dalmatian toadflax is very similar in appearance to yellow toadflax. The main difference between Dalmatian and yellow toadflax are the leaves. The leaves of Dalmatian toadflax are heart shaped with smooth edges and are arranged alternately on the stem. The leaves and stem are a whitish to bluish in color. The flowers are very similar to yellow toadflax, they are bright yellow with an orange throat and look like a snapdragon flower. Another distinction between yellow toadflax and Dalmatian toadflax is that the Dalmatian can grow up to 3 feet tall.
What can you do? The best strategy for managing toadflax infestations is an integrated approach that focuses on preventing seed formation and vegetative spread. Having multiple approaches to toadflax is crucial because of the wide range of conditions it inhabits and due to its genetic variability. Mechanical methods such as hand pulling and digging are effective in newly established, small patches. Hand pulling toadflax works when the weed is young and the conditions are moist. Mowing will not help reduce toadflax populations because it does not remove the root system. Sheep will graze toadflax when it is in bloom but this is not enough to control an infestation. There are a number of biocontrols being studied; one in particular has shown promising results. This insect is mecinus janthinus and it is a stem boring weevil that causes wilt and suppressed flower production. Herbicides are an effective method for control of toadflax. Revegetation is a very important tool in managing toadflax. Integrating some or all of the above-mentioned tools into a long-term management strategy will help control Dalmatian toadflax infestations. If you have any questions about noxious weeds call the weed district.
Visit the MWCA Weed ID pages for additional information and pictures of dalmatian 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.