By Darren Hefty

Yes, there is a silver bullet.  You’ve been looking for it all along, and it’s right here.  The silver bullet for getting the biggest yield gain in your soybeans has been right under your nose the whole time.  It’s weed control!  Hold on.  Don’t quit reading just yet.  Universities and private research firms have documented this for decades, and now with Roundup-resistant weeds, it’s happening all over again.  If your weed control isn’t GREAT, your yields won’t be either.  Here are some things to look at on your farm that could improve your weed control in soybeans.

  1. Three Pre Strategy – Brian and I have worked hard to promote the use of pre-emerge herbicides for years.  In soybeans, we believe the only way to get GREAT weed control is to use a combination of herbicides totaling three different sites of action.  For example, use Prowl plus Authority MTZ (Authority + metribuzin).   For farmers who do this, weed control is rarely a problem post-emerge.
  2. Post-Emerge Residuals – Since weeds like pigweeds and lambsquarters are tough to kill post-emerge, yet they continue to germinate and grow new flushes all through the summer, you may consider adding more residual to your program.  Warrant, Outlook and Dual can all be sprayed post-emerge.  While they have no burndown effect on emerged weeds, they will stop future weeds from germinating for another few weeks, extending your residual control, hopefully until your crop has time to fully reach crop canopy.
  3. Scouting and Weed ID – The days of just loading up with Roundup and spraying every field are really over for most soybean farmers.  Even Liberty could use some help on a few weeds, although it’s still awfully good.  The real key to GREAT weed control and GREAT yields is scouting your fields regularly (at least once, if not twice per week) and properly identifying the weeds in your field.  The scouting is up to you, but we have a weed ID tool you can download for your smartphone or iPad called the Ag PhD Field Guide.  There are pictures for a large number of weeds and herbicide recommendations, as well.
  4. Picking the Right Tankmix Partner(s) – To get perfect weed control, it will take one or two tankmix partners with Roundup to get the job done.  The question is which products to use.  Here’s a quick list of weeds and the best helpers to add.
    • Flexstar (or Cobra where Flexstar is not labeled) – Pigweed (Waterhemp, Palmer, etc.), Kochia
    • Harass – Lambsquarters
    • FirstRate – Giant/Common Ragweed, Morningglory
    • Pursuit – Wild Buckwheat, Black Nightshade
    • Cadet or Resource – Velvetleaf
    • Select Max – Volunteer Corn, Annual Grasses