What is in this article?:
When you’ve got herbicide-resistant weeds, variety selection can’t be all about yield, says Lisa Behnken, University of Minnesota Extension regional educator. “If I have giant ragweed in my Roundup Ready beans that I can’t control, those yields will definitely be affected.”
Growers should first be looking at the top third of the varieties, based on yield, she says. “But from there you need to consider disease resistance and physical characteristics that best fit your fields. Those are often more important than getting the top yielder.”
Incorporating the LibertyLink system into a crop rotation requires planning, she notes. “It’s not just a one-year thing. That’s one of the reasons some Midwest growers have been resistant to try it – they just don’t want to commit.”
Another drawback to the system was that some early LibertyLink varieties weren’t as strong as their Roundup Ready counterparts, notes Behnken. She and colleagues have done field trials measuring the performance of LibertyLink soybean varieties for four years at several locations in southern Minnesota. “In the first few years, some of the LibertyLink varieties didn’t always yield as well as Roundup Ready versions. In the last two years, though, we’ve seen those differences tighten up. Some of the top-performing varieties this past year were LibertyLink.”
“The main reason growers are going to LibertyLink is a problem with glyphosate resistance,” she continues. “As we see more of those problems, we’ll see more adoption of the LibertyLink system.”
That’s definitely been the case where sugar beets are grown, specifically Roundup Ready sugar beets. Glyphosate-resistant waterhemp has been documented in western Minnesota and has prompted growers there to try LibertyLink soybeans, says Clara City, Minn., seed dealer Mike Bosch. “I’ve had several customers try them over the past three years. The big question was always about yield. This past season we saw that the yields for LibertyLink varieties were very competitive with Roundup Ready 1 varieties and are close to catching up to Roundup Ready 2s.
“Another advantage I’ve heard from customers is that LibertyLink soybeans seem to respond better on high-pH soils, which are common in our area,” he adds.
Overall performance and yield of the LibertyLink varieties have pleased one of Bosch’s toughest customers – his dad Lee. “About 20% of our soybeans are LibertyLink, and over the last two years they’ve yielded as well as the Roundup Ready fields,” he says.
Timing the herbicide application can be trickier than with glyphosate, he notes. “Last spring we made our first Liberty application when it was cold and wet, and didn’t get much control. But two weeks later, after things had warmed up a bit, we re-sprayed the field and got good control.”