By Harold Watters, Ohio State University Extension Field Agronomist
Got weeds? Did you use a burndown, and apply a pre-emergent herbicide at the same time? Then you had some luck on your side and you had patience. What a spring.
As I drive around today however, I find corn and soybean fields that have weeds taller than the crop. That means we missed something. And yes I know we now have dicamba soybeans. But we still need a good burndown and those pre-emergent herbicides. Part of our goal is to slow down weed emergence so they are shorter when we do spray our post application. 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.
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.
Waterhemp? Or pigweed, or Palmer?
I have been getting calls and samples the entire month of June. Sounds like it’s a good year for pigweeds in general. One person I just spoke with said the waterhemp was a bit tall in his Liberty beans. My suggestion, spray now, wait three weeks and spray it again (do read the label to make sure that is allowed). If you want to know if your “pigweed” is resistant: https://web.extension.illinois.edu/plantclinic/downloads/herbicide.pdf.
On Mark Loux’s YouTube channel there are videos related to marestail and giant ragweed control, along with his pigweed series: https://www.youtube.com/user/OSUWEEDS.