It’s almost July and we are all done with our soybean herbicide applications. Right?

Got weeds? Did you use a burndown, and apply a pre-emergent herbicide at the same time? Then you did well. That has gotten you off to a good start.

As I drive around today however, I still find soybean (and corn) fields that have weeds taller than the crop. That means we missed something. And yes I know we now have Extend soybeans labeled (and just recently the Enlist bean). But we still need a good burndown and those pre- herbicides. Partly our goal is to slow down weed emergence so they are shorter when we do spray our post application as well as to remove weeds so we start the season with a clean slate. Oh and yes, to get high yields.


You know the drill so I won’t go into that again. But it continues to be our number one weed in soybeans, and yet it is manageable — even in conventional soybeans.

Giant ragweed

The other big problem in soybeans and occasionally in corn is giant ragweed. This quick growing weed has developed tolerance to many of our herbicide programs. It does still respond somewhat to pre-emergent herbicides so hopefully you started there and then for your post application, you will probably need to apply twice, three weeks apart.

  • See the Ohio, Indiana and Illinois Weed Control Guide and read the “Problem Weed” section near the back, and the Factsheets starting on page 208. Got no guide? Download a free copy from Mark Loux’s website:, see under resources on the right.
  • Also on Mark’s YouTube channel there are videos related to marestail and giant ragweed control, along with his pigweed series:
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