Weed Control Tips
Jun 22, 2020
Pre-harvest weed control with glyphosate is very effective for the control of perennial weeds such as Canada thistle, perennial sow-thistle, quackgrass and dandelion.
Pre-harvest weed control also provides significant harvest management benefits such as quicker drydown, more uniform maturity, increased combine efficiency and earlier harvest.
Registered crops include wheat, barley, oats, canola, flax and peas. Application to crops should occur when moisture content is 30% or less. In cereals, this is at the hard dough stage when a thumbnail impression will remain on the kernel. In flax and peas, the majority of bolls and pods are brown.
Best weed control is achieved when Canada thistle and perennial sow-thistle are sprayed at or beyond the bud stage. Quackgrass control is best when there are 4 to 5 or more green leaves. To control dandelion, plants should be actively growing and at the bud to bloom stage. (Dandelion may be more effectively controlled with a post-harvest treatment due to better coverage and translocation.)
Post-Harvest Weed Control Tips
Post-harvest weed control is another great opportunity to clean up fields and prepare for next year’s crop.
Glyphosate is commonly used in post-harvest weed control programs, however with the increasing concern for glyphosate-resistant weed development, growers should be utilizing multiple modes of action.
Glyphosate tank-mixes with Express SG or Inferno allow recropping to cereals, canola, flax and soybeans next season. For residual control of broadleaved weeds, Express Pro tank-mixed with glyphosate or PrePass XC will be effective. Only cereals can be recropped next spring after the application of these two products. Paradigm is another option for post-harvest application which offers “Just Go” benefits and multiple modes of action, mix Paradigm with glyphosate, recrop to wheat or barley next spring.
New options for post-harvest weed control include Heat or Distinct tank-mixed with glyphosate. These products provide different modes of action and broad-spectrum control. Check product labels for recropping options as these vary by the date of the post-harvest application.