I'm Ron Patterson with Utah State University extension
in Weber and Morgan counties.
Weeds do not recognize property boundaries so they really
are everybody's problem.
And today's weed warrior topic is yellow star-thistle.
Yellow star-thistle is a winter annual, meeting
at germinates in the fall, produces a rosette,
sends down its taproot.
And then the next summer it grows,
it sends up the flowering stalk, produces the seed,
and after it produces the seed, then it dies.
Yellow star-thistle is most easily recognized
when its flowering and it has these vicious spines
right around the flower head.
It's got that yellow flower and then
the spines come around the flower.
The stems also have this wing, or fin,
that grows up the stem all the way up to the seed head.
The seeds have this little plumule.
So they'll spread a little bit by wind but mostly by water,
and the thorns fastening onto people, onto animals,
onto tires, will carry that seed and disperse it
along any pathway that you go along.
The rosette, that forms in the fall,
looks a lot like a dandelion rosette would be,
or a prickly lettuce.
So it's kind of hard to distinguish.
But we don't like dandelions or prickly lettuce
anyway so anything you see something like that go ahead
and spray it.
Especially if you know there's been yellow star-thistle.
As you go up the stem, the leaves
get a narrow stripe like leaf.
And, again, the edges of the leaf
will go down into these fins and-- go down the stem.
Now this is a pretty typical height for yellow star-thistle,
18 to 24 inches.
But they'll produce flowers anywhere from 6 inches
to 6 feet.
Yellow star-thistle usually will get its foothold
along trails, and roads, and pathway
but it spreads quite readily through the range.
And it is one of the worst weeds in the Western United
States in rain situations.
It reproduces only by seed.
These seeds will be viable once that flower,
you get a flower appear.
Within about eight days you will have viable seed.
And those seeds will, most of it will germinate
within that first year.
Very few of them will survive past four years.
So if you can keep this from going to seed for four or five
years, then you've got a really good upper hand
on this yellow star-thistle.
Yellow star-thistle doesn't usually
get established in pastures.
But if your pastures are overgrazed or not
managed properly, it's very possible.
Yellow star-thistle causes a condition in horses
called chewing disease, which is usually fatal.
Cattle, sheep, and goats can eat yellow star-thistle, pretty
much any stage, but the goats are really
the only ones that will still eat it when there's
the thorns on the seed head.
But they don't have the same effect
that the horses do when it comes to grazing yellow star-thistle.
Now prevention is always the best cure for any weed problem
that we might have.
And so, you want to watch your equipment.
If you're cutting hay, be sure that you
got hay that is weed free.
Doesn't have the yellow star-thistle in it.
You're watching the equipment, construction equipment,
the agricultural equipment, your ATVs on the road.
If you're going anywhere where there's yellow star-thistle,
check to make sure you're not picking up hitchhikers.
You walk along here and these thorns
will stick into your clothes and carry the seed along.
So that prevention is really, really important.
But if you get it on your place then there
are some things that we can do.
Biological controls are a tool that we
can use to help keep the population of the weeds
under control.
They don't wipe it out but they help
us to manage it a little bit better.
And there are several that we use for yellow star-thistle.
Here we have a cage set up to get a population of a seed head
we will established in this particular star
star-thistle patch.
So if you do get yellow star-thistle at home,
there are a couple of simple things
you can do to keep it under control.
A shallow tillage with a tiller or a shovel or something
like that, you can dig it up.
You'll have the best luck if you dig it up after it's bolted,
before you produce seed.
Dig it up just a couple inches below the crown of the plant.
Mowing will work.
If you mow it before it goes to seed, but after it's bolted,
keep that from going to flower.
That does a pretty good job.
You just have to do it on a regular basis
and keep after it because it will
try to send up stock again from that crown
and try to go to seed.
So tillage, digging up or mowing are all pretty good.
As far as herbicides go, you can use Dicamba or 2, 4-D as,
long as the temperatures aren't too hot, which
would cause it to volatilized and drift to the plants
that you don't want it to be on.
Or Glyphosate.
Those three products are good homeowner products
that you can use on yellow star-thistle.
A couple of other techniques that
may help in your efforts to control yellow star-thistle
would include, the application of a pre-emergent herbicide
such as Treflan, Surflan, Balan, one of those types of products.
The timing is very important on those.
It needs to be done before the seeds germinate in the fall.
So an early to mid September application
would work best for that.
There's also a soil solarization technique.
This is done best in the middle of the summer
when it's hot, long sunny days, when you can get the best
cooking effect of that.
It's easily applied in a landscape situation.
A little bit tougher but there's still a farm applications
that work just as well.
The best time to spray your herbicides
on yellow star-thistle is in the fall
when it's in the rosette stage or early spring.
You got that rosette there rather
than waiting until it's flowered and gone to seed.
That way you're controlling it at the small stage.
In a pasture or rangeland or right-of-way situation,
some of the herbicides that you can use
would be Telar or Escort or Milestone, Transline,
some of those products.
The reason you don't want to use those in your landscape
is that there's a fair amount of soil activity.
It will kill plants that you don't want it to kill.
So in pastures, right-of-way, rangeland,
those type of products work quite well on star thistle.
Whenever you use a herbicide, it's
very important to understand and follow the label.
I will have more information, some links in the description
of the video, on herbicides and some fact sheets
on yellow star-thistle.
Weeds really do not recognize property boundaries
so it's important for us to all to do our part.
Let's get this yellow star-thistle under control.
Let's be a good neighbor.
Be a Weed Warrior.