When managing weeds in soybean fields, you need a game plan encompassing the current and coming season, says Brian Weihmeir, an agronomist with LG Seeds in south-central Illinois.
That plan should also go beyond soybeans. In the Midwest where a corn/soybean rotation is common, Weihmeir emphasizes growers need to keep their corn fields clean or risk an uphill battle the following season.
Tip #1: Overlap residuals to prevent weed emergence:
Weihmeir says there’s a need for a mentality shift regarding soybean weed management timing. The easiest way to keep weeds at bay is to prevent them from emerging via overlapping residuals, he says.
“Make sure you’re putting down a good pre-emergent herbicide with residual and then come back for post-application residual herbicide to take us all the way to crop canopy,” he says. Pre-emergence spraying should happen as close to planting as possible.
Tip #2: Quick canopy can keep weeds from germinating:
The next major focus is keeping weeds from germinating, and that hinges on getting a quick canopy, according to Weihmeir. That should influence farmers’ row spacing and seed selections.
“Talk to your seed provider about finding the right soybeans for your farm,” he says. “If you have a light field, for example, make sure you’re talking to your seed provider about getting a soybean that gets a little bit taller and bushier so we can close the rows quicker.”
Tip #3: Walk fields and identify weeds:
Palmer amaranth and waterhemp cause Midwest soybean farmers the most trouble. “They can grow an inch per day, so you might walk out in the field and hardly see anything and then come back three days later and they’re ankle-tall and we’re too late,” warns Weihmeir. Farmers need to scout fields and take a proactive approach to herbicide application.
“Pick several random areas within each field to scout and identify weeds,” Weihmeir recommends. He says farmers should also make note of weed height and be ready to tweak herbicide plans if unexpected weeds like grasses or cocklebur appear.
Tip #4: Switch up modes of action:
It’s important to vary what herbicides you’re using on both corn and soybeans to stay ahead of herbicide resistance, according to Weihmeir.
“LG Seeds offers different trait offerings like Xtend®, XtendFlex®, Enlist E3® and conventional to give growers choices based on what works best for them,” Weihmeir says, adding, “We’re very fortunate to help the grower by giving them those choices.”
This season’s supply issues could force some producers to change herbicides more than they otherwise would. It’s important to know your options if your preferred herbicide isn’t available, Weihmeir says, offering this example: “If you’re planting Enlist E3® soybeans and can’t get Liberty® herbicide, know that you can also use 2,4-D or Roundup®.”
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