Key identifying traits
- Flowers are small,
yellow, and have 4 petals
- Plants range from 1-4’
tall & have a 3-5’ long taproot
- The rosettes have
bluish-green leaves covered with a fine hair
- Leaves are succulent
with a cream colored mid-rib from tip to base and range from 1 ½
-7” long
- Plants have purplish
brown seed pods, each containing one seed
Biology and ecology
- Dyers woad grows as a
winter annual, biennial or short-lived perennial
- It is native to
southeast Russia
- In Washington state it
has been found only in Kittitas County but no plants found since
1993
- Dyers woad has been
known as a source of blue dye (indigo) since the 13th century;
it is sometimes found in gardens or being sold as an ornamental
Control
Prevention –
Learn to identify plants; start monitoring early in the season; do
not allow plants to produce seed
Biological –
The native rust pathogen Puccinia thlaspeos is effective in
preventing some seed or fruit production & seems to be spreading
naturally to new woad populations, controlling further spread
Cultural –
Plant competitive grass or other cover crop
Mechanical –
Hand pulling is very effective for small infestations; tillage or
mowing can be effective and help reduce seed production
 Chemical
– Herbicides will be the most effective on rosettes; metsulfuron plus
2,4-D is said to produce good results; refer to the
PNW Weed Management handbook for more chemical recommendations
|
All photos ©
Steve Dewey,
Utah State University, www.forestryimages.org |
