I'm Ron Patterson with Utah State University Extension. Weeds do not
recognize property boundaries, and so they really are everybody's problem.
Today's Weed Warrior topic is dyer's woad. Here's a young dyer's woad - you can
identify them quite easily with that light-colored midrib; goes right down the
middle of the leaf, but this one was going to probably sit here all summer
long as a rosette and send down a good tap root and then next year it'll bolt
into a flower if it doesn't get pulled up. Notice that the rosettes have a
simple leaf, and it's almost entire, and they have a long petiole that goes from
the rosette up to the leaf blade. On the other hand the leaf on the flower stalk
is a clasping leaf where it's attached right down right around that stem. The
flowering stock is kind of a brownish reddish color, and the leaves are also a
little bit kind of a bluish tint or grayish tint to those leaves. As a
biennial dyer's woad will germinate in the spring or summer and grow and form a
rosette. This rosette will grow throughout the summer and send down a
taproot. It's a massive tap where you go down as far as five feet, and it will
give that dyer's woad a competitive advantage over some of the other plants
around in the springtime. So the rosette then will set through the winter and get
a chilling process - it's called vernalization - so that vernalization will
chill that and tell it to send up the flower stalks the next spring. The second
spring it will send up this flower stalk and produce seeds in that second growing
season. Sometimes when dyer's woad germinates late enough in the summer or
early fall, it'll put on a large enough rosette - grow large enough rosette - to go
through the winter vernalization and then send up a seed stock. So in that
case it actually behaves more like a winter annual, where it puts up a seed
stock in just that one season; it doesn't go through a full summer growing season.
Another situation that can happen is if you mow off the dyer's woad that doesn't
kill the root; it will send up buds from the root down here and so...
so just mowing dyer's woad doesn't really do the job. It'll send up buds and kind
of behaves in that way more like a perennial; you can go through two or
three years of dyer's woad of that same plant until it sends up a seed stock and
produces seed. The thing is dyer's woad is a mono carpet biennial, in other words
it dies once it produces that one season of seed it will die - that root will die -
but then it's produced 500 seeds, so we have to come up with control options for
these different stages of growth. So dyer's woad reproduces by seed. The main
control efforts have to focus around keeping it from going to seed, or keeping
the seed from getting planted, so that's what we'll talk about is how to keep
this from producing seed and spreading too places we don't want it to be. Now
weed prevention is the best control option we have, so some of the things we
can do to prevent it from getting onto our place is: feed weed-free hay, or
clean our equipment - our farm equipment, construction equipment, ATV equipment.
Anything that we've been operating where it's been infested with dyer's woad, be
sure to clean that before you move it to some other place that hasn't been
infested. Water is probably the most common way for dyer's woad to be spread.
Whether it's along rivers or streams, along irrigation ditches, or even erosion
coming down from the mountains, we want to make sure that we keep the dyer's woad
away from situations where it can spread with the water. Now when you're trying to
control the seedling, or rosette, or even early bud stage, you can use a herbicide
application to control those. A broadleaf weed control such as 2 4D or Telar
or Escort. I'll put links in the description of the video that will take
you to a more detailed description of those herbicides and how you would apply
those, but that's how you do the herbicide application. Now when dyer's woad
is at the blossoming, or bud stage, or seed stage, you'll want to take out the
root. Chop those crown off on that dyer's woad so that you've got it; you're going
to kill the plant that way. You want to have at least a couple of inches of the
root below the crown to make sure that you've
got that killed out. If you don't, if you cut off above the crown or right at the
crown, it will send up buds from that crown and you'll get more dyer's woad
growing. If the seeds - if it's just in blossom stage like this - you can let it
lay; you don't have to throw it, put it in a bag, but if it's producing any seed at
all you need to put that into a bag and throw it away. Don't leave it on the
ground, or it will drop those seeds and produce more dyer's woad. There is a
biological control - it's a fungus, a rust - that will get into the system and
it will affect some plants but not every plant. So you can't really rely upon this -
this rust to do the control that you need on the seed production. So it's
there but but don't rely on it. Dyer's woad is a serious problem in Utah but
ignoring it will not make it go away. Weeds really are everybody's problem, and
it will take several years of control efforts to get a handle on this problem.
So be a good neighbor: be a Weed Warrior.