Cultural
Management
Seeding
and maintaining aggressive grasses such will help in competing with
Russian knapweed and slow its spread. Proper fertilization, grazing,
and supplemental irrigation of grasses are always effective cultural
control methods.
Due
to the allelopathic properties of this weed, supplemental control
methods, such as judicious use of herbicides, may be needed to give
grasses a chance to compete. Additional herbicide treatments after
grass establishment may be needed to keep Russian knapweed populations
reduced to an acceptable level.
More
complete information on grasses can be found on the Grass
Seeding on the Eastern Front-Range of Colorado page or by contacting
the Natural
Resources Conservation Service.
Mechanical
Management
Mowing
and other mechanical methods can be employed every 14 to 21 days
to prevent seed set and to stress the plants. Whether these efforts
will reduce root mass and plant stand is unknown. As a creeping
perennial, Russian knapweed is difficult to control by hand-pulling
or grubbing. Cultivation is marginally effective on crop lands.
Biological
Management
No
effective biological control agents are known currently for this
weed. Horses cannot be allowed to graze this knapweed as they can
develop chewing disease. A root nematode (Subanguina picridis)
Has provided poor control.
Herbicide
Management
A
number of herbicides are labeled for use on Russian knapweed. Those
that have been effective when used independently or in combination
with each other are: chlorosulfuron (Telar), picloram (Tordon),
2,4-D, glyphosate (Roundup, Rodeo), dicamba (Veteran 10G), and Curtail.
Refer to table below for more information.
Herbicide |
Labeled
Site * |
Rate
(per acre) |
Application
Time |
| Tordon
22K |
All |
1.0qt.
2qts.
for spot treatment |
Bud
to early-flower stage and/or fall rosette. |
Tordon
22K +
2,4-D
Amine |
All |
1.0
pt. +
1
qt. |
Bud
to early-flower stage and/or fall rosette. |
| Curtail |
All |
3
to 4 qts. |
Bud
to early-flower stage. Fall is most effective. |
| Telar |
NC |
1
to 3 oz. |
Perbloom
to early-flower stage and/or 1 oz./ac. to fall rosettes. |
| Veteran
10g |
R
& P, NC |
1/2
to 1.0 lb. per 1000 s.f. |
To
actively growing plants. |
| Transline
& Redeem |
- |
- |
Contact
weed department, online information will be posted soon. |
*
R & P = Range and Pasture; NC = noncrop; Crop = cropland; F
= fallow; All = all of these sites.
Read
the label to insure the herbicide is labeled for your application
site.
