The
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.
Prevention
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.
Chemical
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.
Mechanical
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.
Bio-Controls
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.
