Posted August 10, 2006: Canada thistle is
a frustrating weed. First off, understand that you will never
eliminate it forever. As soon as it is gone, seed drifts in
from somewhere else and takes hold. My objective is to manage
populations to acceptable levels, i.e. patches small enough
to be mowed out of the crops. On the tillage side, I use a
spike-tooth cultivator followed by a rodweeder to pull out
the thistle plants. The spikes loosen the root, and the rod
pulls as much root as the strength of the root allows. I regularly
pull out 6 to 8 inches of thistle root, but the length will
vary by soil type, moisture and weed stage.
If you have thistle, get rid of all sweeps on your cultivators.
A sweep only cuts at the depth of tillage and allows for more
I agree with Jeff Moyer on the use of hay and rye, but I
will qualify the rye idea: You must have enough soil health
to produce at least a 60-bushel-per-acre crop—any less,
and you lose a lot of competitive advantage against the weeds.
I try to build the soil with a plowdown crop first, seeded
late spring to allow a flush of thistle. Incorporate in late
July, and seed to fall rye in the first week in September
after another spike/rod pass. Don't underestimate the value
of fall tillage on thistle either.
We commonly disc our rye stubble and what thistle may be
left is "pulled" out by the disk. The rod is useless
in the heavy straw because it will not clear the residue.
Hay does eliminate thistle, and it provides income at the
The photo shows that Kongskilde has a specialized shank unlike
any other, one with a hook specifically designed to pull and
kill quackgrass. As a matter of fact, the original spikes
for it had a pull-out sheet on how to cultivate to kill quack.
One further detail on my cultivator set-up: Notice the type
of spring mount used. It is two band springs, eliminating
any bushings. The neat part is that it allows for movement
side to side as well as front and back. This gives a whole
new meaning to term “vibra-shank,” the critical
action in shaking out quack roots.