NO-TILL
PERENNIAL WEED CONTROL
Perennial weeds will increase
as the amount of tillage is decreased. The optimum time to control many perennials,
such as hemp dogbane, quackgrass and Canada thistle, is in the fall, especially
in mowed (before Aug. 1) wheat stubble, when herbicide can be translocated to
the roots and rhizomes with downward-moving energy reserves. Rotation of crops
and herbicides can be an effective means of control. Following is a review of
some of the more persistent perennials and herbicide programs that have proven
to be effective. Always add Ammonium Sulfate (AMS) to glyphosate products at 17
pounds/100 gallons of water for perennial weed control. Applying glyphosate in
spray volumes of 5 to 10 gallons per acre can increase weed control.
Glyphosate rates will be
expressed as pounds acid equivalent per acre (lb ae/A). Gylphosate at 0.75 lb
ae/A is equal to 26.0 oz/A of Roundup Ultra Max (3.75 lb ae/gal) and 1.0 qt/A
of Touchdown, Roundup Original, Glyphomax Plus, Glyphosate Original and most
other 3.0 lb ae/gal gylphosate formulations. Gylphosate at 1.5 lb ae/A is equal
to 52.0 oz/A of Roundup Ultra Max and 2.0 qt/A of Touchdown, Roundup Original,
Glyphomax Plus, Glyphosate Original and most other 3.0 lb ae/gal glyphosate
formulations. Read all glyphosate labels to determine whether a surfactant is
needed.
Quackgrass
- Apply glyphosate in the
spring when quackgrass is at least 8 to 12 inches tall, or fall after harvest
before the killing frost with at least 6 to 8 inches of regrowth. Rates: glyphosate
(0.75 lb ae/A).
- Other materials include:
Accent, Beacon and Steadfast
POST on corn. Roundup Ultra on Roundup Ready corn.
Assure II, Fusilade DX,
Fusion & Select POST on soybeans. Roundup Ultra on Roundup Ready soybeans.
Canada Thistle
- Fall Treatment with at
least 8 inch tall plants:
• glyposate (1.13 lb ae/A)
• dicamba (1 to 2 qt/A)
(Check recrop restrictions)
• glyphosate- spot treatment
- 2% solution.
- Stinger (0.67 pt/A) POST
on corn.
- Glyphosate (0.75 lb ae/A)
applied at bud to flower stage of growth on Roundup Ready corn or soybeans
- Other materials include:
Basagran, Distinct, Hornet, Laddok and Marksman POST on corn. Basagran and First
Rate POST on soybeans and Synchrony STS POST on STS soybeans.
Bindweeds
- In wheat stubble before
killing frost:
• glyphosate (2.25 to 3.0
lb ae/A)
• glyphosate - spot treatment
- 2-3% solution.
• glyphosate + 2,4-D ester
(1.5 lb ae/A + 1.5 pt/A.)
• dicamba 1 to 2 qt/A alone
or in combination with glyphosate.
- Apply glyphosate (1.5 lb
ae/A) at flower stage on Roundup Ready soybeans
- Other materials include:
dicamba, 2,4-D, Exceed + dicamba and Marksman POST on corn. Glyphosate on Roundup
Ready corn. Blazer, Cobra, Flexstar, Reflex POST on soybeans.
Hemp Dogbane
- In wheat stubble before
killing frost:
• glyphosate (2.25 to 3.0
lb ae/A)
• glyphosate - spot treatment
- 2-3% solution
• glyphosate + 2,4-D ester
(1.5 lb ae/A + 1.5 pt/A.)
- Apply glyphosate at highest
possible rate at bud to flower stage on Roundup Ready corn or soybeans.
- Other materials include:
2,4-D, Accent + dicamba, dicamba, Beacon + 2,4-D, Distinct (6.0 oz/A), Exceed
+ 2,4-D, Marksman, Spirit + 2,4-D or combinations of dicamba + 2,4-D POST on
corn.
Common and Honeyvine
Milkweed
- In wheat stubble before
killing frost:
• glyphosate (2.25 lb ae/A)
• glyphosate -spot treatment
- 2-3% solution.
• glyphosate + 2,4-D ester
(1.5 lb ae/A + 1.5 pt/A).
- Apply glyphosate at highest
possible rate at bud to flower stage on Roundup Ready corn or soybean.
- Other materials include:
same as hemp dogbane.
Common Dandelion
- In wheat stubble during
mid-October:
• glyphosate (1.13 to 1.5
lb ae/A)
• glyphosate + 2,4-D ester
(0.75 lb ae/A + 1.5 pt/A).
• 2,4-D ester (1.0 qt/A
to 1.5 qt/A).
- Apply 2,4-D ester at 2
pt/A in the spring after soil temperatures are above 50 F and 14 days before
planting corn and 30 days before planting soybeans.
- Apply glyphosate (0.75
lb ae/A or 1.5 lb ae/A) POST on Roundup Ready corn or soybeans respectively.
- Other materials include:
Gramoxone Max + 2,4-D ester + Canopy XL or Sencor applied early preplant to
soybean. 2,4-D ester (1.5 pt/A) + Balance Pro (2.2 to 3.0 oz/A) + atrazine applied
preplant to corn. 2,4-D, dicamba, Distinct, Hornet and Marksman POST on corn.
Liberty (34 oz/A)or Liberty ATZ POST on Liberty Link corn. Classic (0.75 oz/A)
or Synchrony STS on STS soybeans.
Common Pokeweed
- In wheat stubble before
killing frost with plants at least 18 inches tall.
• glyphosate (1.13 to 1.5
lb ae/A).
• glyphosate - spot treatment
- 2% solution.
• glyphosate + 2,4-D ester
(0.75 lb ae/A + 1.5 pt/A).
- Apply glyphosate at 0.75
or 1.5 lb ae/A on Roundup Ready corn and soybeans respectively when plants are
at least 30 inches tall or near bud stage.
- Other materials include:
Beacon, Exceed, Permit or Spirit + Banvel (0.5 pt/A) POST on corn when pokeweed
is at least 18 inches tall. Synchrony STS on STS soybeans.
Johnsongrass
- In wheat stubble before
killing frost with plants at least 24 inches tall:
• Glyphosate (0.75 lb ae/A)
• Glyphosate - spot treatment
- 2 % solution
- Apply Accent, Beacon, Celebrity
Plus, or Steadfast POST on corn with johnsongrass greater than 8 inches tall.
- Apply glyphosate (0.75
lb ae/A) POST on Roundup Ready corn or soybean with johnsongrass greater than
15 inches tall.
- Apply Assure II, Fusilade
DX, Fusion, or Select POST on soybeans with johnsongrass 10 to 20 inches tall.
- Apply Lightning POST on
Clearfield corn with johnsongrass less than 8 inches.
Corn,
Soybean, Wheat, and Alfalfa Field GuideBulletin 827