Friend or foe? Wild, noxious weed or environmentally-sound perennial? Sometimes it takes a trained eye or a magnifying glass to tell the difference.
[(Left) Pictured is a snapdragon flower. (Photo by Kerry Peetz) (Right) Pictured is a toadflax, which bears a resemblance to the snapdragon but is classified as a noxious weed and should be removed from yards and gardens because of its negative impact on the environment and livestock. (Photo from istockphoto.com)]
If you live in eastern El Paso County, chances are you have experienced the dreaded toadflax, although the weed is also found inside city limits. The important question is this: what should we all do to prevent it and why?
Yellow toadflax is native to south-central Eurasia, where it was used for fabric dyes and for medicinal purposes. It was brought to North America in the late 1600s as an ornamental and for health remedies.
Toadflax leaves are narrow, linear, and 1 to 2 inches long. The stems are woody at the base and smooth toward the top. Sparsely branched and 1 to 3 feet tall, the showy snapdragon-like flowers are bright yellow with an orange center and have a spur as long as the entire flower.
We don’t want this weed around because of its extensive root system. It displaces desirable plants, reduces ecological diversity and rangeland value. Yellow toadflax also decreases forage for domestic livestock and some big game species. The plant is known to be mildly poisonous to cattle.
Unfortunately, in states where yellow toadflax is not noxious, it is sold by some nurseries as “butter and eggs” or as “wild snapdragon.” If you receive an out-of-state gift/plant from your Great Aunt Viola, be sure to do a bit of quick research before planting. Also remember to always read the content label listing what species are included in wildflower seed mixes. If toadflax is listed, don’t buy it.
The key to effective control is prevention and using as many management strategies as possible. Prevention is always desirable when dealing with yellow toadflax or any weed. Be sure to check and clean your hiking boots, vehicle/bike tires, pet fur, livestock fur, and farm equipment, thoroughly before leaving a toadflax infested area. Seeds are transported this easy and are ready to hit the ground and grow.
Control management includes; herbicide, mechanical, cultural and biological methods. 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 local infestations.
1). Plant select grasses and forbs as an effective cultural control of yellow toadflax. Bare ground is asking for weed invasions, so maintain healthy pastures and landscapes.
2). 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. Amazingly, Palisade isn’t only known for its peaches. Obtain information regarding the previously mentioned moths and weevil from the Colorado Department of Agriculture’s Insectary located in Palisade.
3) Surprisingly, (thankfully for some) hand pulling or digging is not recommended. It’s unlikely that the entire root will be removed, and several new shoots are likely to start. Tillage is also not recommended for the same reason. Never allow them to go to seed. One mature plant can produce up to 30,000 seeds annually. A single stem has been reported to contain over 5,000 seeds. Keep in mind, that seeds can remain dormant in the soil for up to 10 years.
The best time for herbicide application is during the flowering stage, this is when carbohydrate reserves in the root of the plants are at their lowest. Herbicides that have been somewhat effective on yellow toadflax control are picloram, glyphosate, dicamba, and chlorsulfuron. Repeat applications are necessary to achieve control.
As our growing season comes to an end and the harvest moon shines bright, remember to collect those ugly weed seed heads and skip next season’s fright!
(Kerry Peetz is a master gardener and member of Sacred Heart Parish in Colorado Springs.)