LibertyLink soybeans in a PPO-resistant pigweed environment

LibertyLink soybeans in a PPO-resistant pigweed environment

PPO-chemistry resistant pigweed confirmation puts LibertyLink soybeans in spotlight. How does the technology do in a Mid-South environment?

With the discovery of PPO-resistant pigweeds, inevitable questions about LibertyLink soybeans have arisen. How do varieties stack up in a Mid-South environment?

“Honestly, we’ve been anticipating this since so much PPO chemistry has been applied to pigweeds over the last five or six years,” says Jeremy Ross, Arkansas Extension soybean specialist. “Since they became resistant to Roundup, we’ve moved to a reliance on PPOs to help keep them in check.

“We all hate that it’s happened, though. If it quickly becomes widespread it’ll be a game-changer, no doubt. You can’t beat pigweeds without the necessary tools.”

What has Ross found in variety trials with Roundup Ready soybeans and LibertyLink varieties?

“If you look at individual varieties, every company has one or two that are outstanding depending on soil textures, environmental conditions and the like. As a whole, everything from variety testing and the studies I’ve been looking at, the systems are fairly consistent yield-wise. You can pull out individual varieties and some will be above average and some below.

“For the past several years, we’ve been telling producers to educate themselves as much as possible. Look at variety test data, look at other states’ data, look at company data and try to select varieties – whether LibertyLink or Roundup Read or conventionals – that will perform in the environment you have. Look at multiple years’ worth of data, look for soil textures similar to what you have, at planting dates and irrigation schemes – all of that.

“All in all, it appears that LibertyLink varieties hang with the rest. Of course, I’m referring to the original LibertyLink trait not the newer one that just came out. We haven’t had a chance to check the new LL55 event that just came out this year.”


What about actual management of LibertyLink varieties?

“We’re recommending a pre-plant or pre-emerge application of herbicide to control weeds that come up before there’s a canopy. That’s true for Roundup Ready varieties and conventionals, as well.

“You might have to come in and lay in an additional herbicide three weeks, or so, into the season depending on what kind of weed pressure you have. Then, definitely come in with two shots of Liberty in season.

“We’re definitely recommending LibertyLink varieties in some fields. But in other situations – in fields without bad pigweed problems – Roundup Ready varieties are a perfect fit. If you’re mainly dealing with grasses, Roundup Ready beans are a better option than LibertyLink.

“Believe it, or not, there are still pockets of the state where pigweeds aren’t a big deal and I tell the producers to stick with Roundup Ready.

“On the PPO resistance, hopefully it’s just isolated. Regardless, we need to keep from using PPO herbicides constantly, year after year. Consider a corn/soybean rotation to break up some of those issues.”

State crop update

Where does the state soybean crop stand currently?

“Ten days ago, I was still getting calls from producers looking to plant. A lot of those calls were from (northeast Arkansas’) Crittenden County and Mississippi County where the Mississippi River came up inside the levee and ruined their initial crops. By now, I think everyone has planted what they’re going to.

“We have two crops in the state. The southern part of the state mostly got planted on time and there are beans there approaching R-6 to R-6.5. Some of those look pretty good.

“Other beans have been planted in the last two or three weeks. Those will struggle, especially in these very hot, humid conditions. This heat will be tough on those beans to get up and going before we get a killing frost in October or the first of November.

“Things are strung out. We have growers that will start to harvest within the next month. Others will be hoping to harvest at Thanksgiving.

“I think everyone is ready for this growing season to end. With all the wet weather and then the heat and, now, worm pressure, it’s been a struggle from start to finish. Frogeye leafspot and SDS is starting to show up, as well.

“Right now, it looks like we’re going to have to spend some more money on irrigation, insecticides, and fungicides to deal with these problems. That’s definitely true on some of the really late-planted crop.

“Unfortunately, with the conditions we’re seeing I don’t foresee record yields like we’ve seen the last two years. This is a more typical July where we’ve hit some 100-degree temperatures and it’s been a while since we’ve seen such heat for an extended period. Don’t misunderstand, the beans are doing okay but I don’t think things are lining up to see incredible yields.”

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