The Bozeman courier. (Bozeman, Mont.) 1919-1954, 1925-07-15
ERADICATION OF
CANADA THISTLE

Canada thi.sles are spreading ct
an alarming rate in Gallatin valley,
especially in the irrigated sections Of
the valley. Controlling this weed is
not a simple problem as several fac
tors must be considered. A living
mast be made on the farm while an
attempt is made to control the this
tie. There are two kinds of plants,
the male" and the female"
The male plants do not produce
seed, but spread rapidly by means
Of roots. The female produces seed
and also spreads by means Of roots.
Wherever a thistle appears every eff
fort should be made to eradicate it az
once as large areas result rapidly
from a small patch.
ROotstocks branch and grow out
horizontally in all directions often to
a length of ten feet or more in n
season. They may be found from a
few inches to three or four feet be-
low the surface of the soil. At al
most any time during the growing
season buds will form on these hOri-
zontal roots and send up new stems.
1t is in this manner that thistles
spread so rapidly.
In order to eradicate Canada this
ties it is necessary to keep down all
top growth and thus give the plants
no opportunity to prepare and store
a reserve supply of food in the roots.
If the underground growth is not re-
plenished by food which can be made
only by the aid OF green leaves and
stems the plant will eventually die
Of starvation.
In some seasons more seed is pro-
duced than in others. The seed Is
scattered chiefly by winds and irri-
cation water. Tillage implements
carry the seed around and especially
the threshing machine. Impure seed
may introduce the weed.
Where there are only small patch
es Of thistles present, starving or
smOthering them is a very effective
way of killing them. No top growth
is permitted and in smOthering this
is done by covering Che patch with
heavy tar or building paper weighted
down to keep out all light. This is
only practical with very small areas
IF the infestation is great summer
following is the only sure remedy
The land is plowed in the spring
as soon as the soil can be workeJ
and all land must be cut and turned
In the operation of blowing. During
the season the land is cultivated sui
ficiently to keep the thistles below
the surface with a duck foot cultiva
tor. Cultivation should be deep an,
is best done with an implement tina
will cut off all growing plants tw
or three inches below the surface
Sharp blades are necessary in orde
to cut off the plants as dull blade
make it impossible to do good wOrl
Smother crops have been used sue
cessfully in controlling the weed, e.
pecially on rich soils. Thistles do NJ
withstand shade well. In p~reparatio
for the smother crop it is desirabl
TO pillow the land during the summ'
or early fall. Clean cultivation (
this plOwed land during the fall ar
the following spring will check Il
weeds materially ard provide a cles
seed bed for the smother crop.
Alfalfa is considered by many
be the best smother crop availab
as it grows well in the irrigated va
legs where Canada thistles are a Sc
ious pest. Alfalfa is cut sever
times during the growing season. Al
so it is effective in holding the chi:
les in check.
Annual crops such as the SIN.
grains and peas also have been fou
helpful. Plenty of seed is sown a
these crops are harvested before
thistles bloom. PlOw the ground j
mediately after harvest and keep
clean during the remainder OF I
growing season.