By Darren Hefty

The best weed control out there is the method that nature gives us: crop canopy.  When a crop is big and tall and no sunlight is hitting the ground, new weeds won’t start growing.  I bring this up because as crops like wheat are harvested across the country, the weeds will now take advantage of that situation.  With a little rainfall, they will begin taking over fields.

That’s a long introduction to the need for post-harvest burndowns.  Historically, the products of choice have been:

  • Roundup
  • Dicamba (Clarity or Banvel)
  • 2,4-D

Roundup is good on such a wide variety of weeds including nearly all of the grass species, perennial weeds, and most broadleaves.  However, with Roundup-resistant weeds such as kochia, pigweed, ragweed, and marestail, dicamba and 2,4-D are commonly being added to the mix.

The other downside to Roundup is that it has no residual control.  Adding especially the dicamba products can add a week or two to the residual, but it’s still not much.  If you have 45 to 60 days before your next wheat crop goes in, or if you have until next spring, there are longer term residual products that could fit the bill while adding significant burndown help.  Sharpen and Valor can each be used in front of a wide range of crops.  They could help you avoid making time-killing extra trips to stop later-emerging flushes of weeds.

So as your post-harvest burndown begins, look beyond a straight Roundup treatment.  2,4-D; Dicamba; Sharpen; and Valor could all be options for you depending on your weed spectrum, crop rotation, and desired length of residual control.