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Yellow toadflax



Yellow ToadflaxThe key to controlling yellow toadflax is to destroy seedlings that emerge from the soil seed bank, limit vegetative spread of colonies, and maintain a cover of native perennial plants to discourage future infestations.


Be sure to check and clean your hiking boots, vehicle/bike tires, pet fur, livestock fur, farm equipment, and construction equipment thoroughly before leaving a toadflax infested area. Seeds can be transported very easily on these items and ready for deposit in an otherwise uninfested area. Watch out for fill dirt and landscaping soils, also another means of dispersal for toadflax seeds into uninfested areas.


The optimal 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 (Tordon 22K*), glyphosate (Roundup**), dicamba (Banvel), and chlorsulfuron (Telar DF). Repeat applications are necessary to achieve control.


Hand-pulling yellow toadflax can be effective for small infestations. This should be done before seed-set and repeated as long as there are viable seeds in the soil (up to ten years). Hand-pulling, if repeated for a number of years, may also deplete the nutrient reserves in the root system. Mowing will reduce the year's growth and reduce the amount of seed set, but is not an effective option for long-term control. Cultivation is effective in controlling yellow toadflax if performed for two years 8 to 10 times the first year, 4 to 5 times the second.


One species, Calophasia lunula is effective if used in an integrated weed management program. The C. lunula larvae feed extensively on the leaves and flowers of toadflax, severely damaging the plant. C. lunula is available through the Colorado Department of Agriculture's Division of Plant Industry's Biological Pest Control Section. You may contact the insectary by dialing (970) 464-7916.

*Tordon 22K is a Restricted Use Pesticide, an applicators license is required in order to use this product. **Roundup is a non-selective herbicide and may injure non-target vegetation.


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