Noxious weeds in Gilpin County
Yellow toadflax (Linaria vulgaris)
 
Photo courtesy Adams County Weed Dept. ____________
Photo: Irene Shonle
State law: Refer to the State
containment map ( scroll down) to see where it must be eradicated
or contained in Gilpin County.
Quick facts:
Perennial with stems that grow from one to three feet tall and
narrow, linear leaves pointed at both ends.
A mature plant can produce up to 30,000 seeds annually a single
stem has been reported to contain over 5,000 seeds. KEEP this plant
from going to seed!
Seeds can remain dormant in the soil for up to ten years. In Gilpin
County, the plant usually goes to seed in mid-late August.
Yellow toadflax can reproduce both by seeds and vegetatively. It
can aggressively form colonies through adventitious buds from creeping
root systems.
It is somewhat poisonous to livestock.
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 may 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).
Caution: there is a native plant, Golden
Banner (Thermopsis divaricarpa) which people sometimes
confuse with toadflax. If you look at the leaves, it is impossible
to mistake them. The leaves of yellow toadflax are linear. The leaves
of Golden Banner have three leaflets (like a clover).
Golden banner has leaflets like a clover -- ------Yellow toadflax
has linear leaves
Additional information on yellow toadflax:
http://www.ext.colostate.edu/pubs/natres/03114.html
http://www.co.silverbow.mt.us/weeds/dalmatian_and_yellow_toadflax.htm
http://www.colostate.edu/Depts/CoopExt/Adams/weed/ytoadflax_mgt.htm
http://www.colostate.edu/Depts/CoopExt/Adams/weed/ytoadflax_id.htm
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