Cultural
Management
Seeding
and Maintaining selective perennial grasses can be an effective
tool. Early emerging grasses that utilize early season moisture
have reduced spurge density and limited the spread and establishment
of new infestations. Sequential glyphosate (e.g. Roundup) applications
followed by a seeding of Luna pubescent wheatgrass, Ephraim crested
wheatgrass, intermediate wheatgrass, Sherman big bluegrass, or Bozoisky
Russian wild rye, has shown to be effective in reducing an infestation
of spurge in Wyoming. Proper grazing management and eradication
of small spurge infestations are always desirable cultural tools.
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
Mechanical
control of spurge is difficult because it is a creeping perennial.
However, multiple stresses applied to plants are very effective.
Frequent mowings through summer reduces the herbicide application
rate needed in the fall. Mowing spurge a regular intervals 4 to
6 times per spring/summer is an effective stress treatment that
will reduce root food reserves and prevent seed set. Mow as plants
regrow and before flowering stage. Spurge's milky sap has been known
to gum up mowers.
Cultivation
can be done at two to four week intervals, but is costly and can
bare soil to erosive factors. Research results are not available
that indicate whether stand reduction or eradication can occur from
the sole use of mechanical treatments.
Biological
Management
Both
sheep and goats have been found to be effective grazers of spurge.
(The milky sap of this weed is incurious to cattle and horse mouths.)
Grazing sheep can commence after spring regrowth reaches two to
six inches tall, but before the flowering bract stage. Goats can
graze spurge at any time. Grazing can proceed to mid August or so.
Do not overgraze. If animals are turned into a site after the spurge
has set seed, quarantine animals in a corral for seven days before
releasing them into a non-infested pasture. Sheep may need a breaking
in period of two weeks before they readily eat spurge.
Several
insect species have been released by the USDA/APHIS that affect
spurge. Of the flea beetles three species have been found to be
most effective. Apthona nigriscutis, Apthona lacertosa, & Apthona flava have been found to be effective after three years
on large infestations. Contact the Adams County Weed Department
or your local extension office for details on these flea beetles.
Herbicide
Management
Herbicides
that have been effective when used independently or in some combinations
are: picloram (Tordon), dicamba (Banvel), 2,4-D (aquatic formulations)
Glyphosate, imidazol and fosamine are suitable for use on riparian
sites. Picloram and dicamba can injure or kill trees. If a solo
herbicide treatment is used, application time is critical. Refer
to the table below for more information.
Herbicide |
Labeled
site* |
Rate
(per acre) |
Application
time |
Remarks |
Tordon
22K |
R&P,
NC |
1.0qt.-repeat
annually 3-4 years.
2.0qt.-Treat
2 consecutive years. |
Spring
following appearance of true flowers and/or fall regrowth. |
Use
the 2qt. rate as a spot treatment. Upper rates may cause grass
damage. |
Tordon
22K
+ 2,4-D Amine |
R&P,
NC |
1pt.
+ 1qt. |
Spring
following appearance of true flowers and/or fall regrowth. |
1
Treatment per year for 2-4 years should provide good leafy spurge
control. |
Banvel
+
2,4-D Amine |
R&P,
NC |
1qt.
+ 1qt. |
Spring
following appearance of true flowers and/or fall regrowth. |
Two
treatments per year for 1-4 years should provide good leafy
spurge control. |
2,4-DAmine |
All |
1qt. |
Early
Spring |
Prevents
seed formation. Retreatment may be necessary to prevent seed
formation. |
Plateau |
NC,
Riparian |
12.oz |
Fall
treatment prior to hard freeze. |
Can
safely be used under trees and riparian areas. Add methylated
seed oil surfactant. |
*
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.
