Most people know they should eat a healthier diet, but it often takes a medical scare to motivate them to change. Most soybean growers know they should add more diversity to their weed control plans, but it often takes herbicide-resistant weeds in their fields to motivate them to try a new system. The hesitation to move away from the simplicity of glyphosate has been one of the biggest reasons many soybean growers in the northern half of the country haven’t tried LibertyLink soybean varieties. But as glyphosate-resistant weeds continue to appear in an increasing number of Midwest fields, more growers may soon be motivated.

“We have glyphosate weed-resistance issues across most of the state of Minnesota,” says Lisa Behnken, University of Minnesota Extension regional educator based in Rochester. “Giant ragweed and waterhemp are the two big ones that have confirmed resistance to glyphosate, but there are others in development.”

While there are several robust herbicide systems for corn, and a lot of herbicide options, she notes that herbicide choices in soybeans are still somewhat limited. “The LibertyLink system is a good option for growers who have weeds resistant to both glyphosate and ALS inhibitors,” she says. “We tell growers they need to develop a five-year weed-control plan to help avoid herbicide-resistant weed issues, and LibertyLink could fit nicely into that plan.”

 

Early limitations

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.”

 

More northern varieties

Because of early weed resistance issue in the southern states, many of the early LibertyLink soybean varieties were developed for Group 3, 4 and 5. “Growers in the South have been dealing with glyphosate-resistant Palmer amaranth for several years,” explains Arlene Cotie, soybean product manager, Bayer CropScience. “Agronomists in the Corn Belt estimate that the Midwest is about three years behind the South, in weed resistance development. In the next few years we could see some significant increases in resistance issues.”

The company’s annual grower surveys on the topic show a sizeable increase over 2011 in the number of farmers saying they have resistant weeds on their farms, says Cotie. “That number is now in the double digits, according to the May 2012 survey.”

She says Bayer CropScience and the seed companies offering LibertyLink soybeans anticipated that growth and will be offering a record number of Group 0-3 varieties for 2013. “The biggest increase will be in the Group 2.5-4 varieties, but there are also a lot of new numbers for the northern tier of states.”

Stine Seed will be offering almost 60 LibertyLink varieties for 2013, which is up from just under 45 last season. “Of the 60, almost 40 of them are new numbers,” says Stine’s David Thompson. “We’re definitely seeing more interest from growers in the Midwest, especially where there are multiple Roundup Ready crops grown. Growers want to preserve Roundup Ready technology’s effectiveness. That’s why they’re interested in adding LibertyLink soybeans. They won’t replace Roundup Ready – they complement it.”

Jack Carlson, WinField Solutions soybean director, agrees that there have been pockets of faster adoption of LibertyLink soybeans. “Overall, we’ve seen a gradual increase in their use in the Midwest, and Croplan is offering about a dozen varieties for next season.

“But it’s just not as convenient as glyphosate, and that has held some growers back from trying it,” he adds. “Herbicide application is more involved, with a tighter application window in the spring.”

A shortage of Liberty herbicide last season didn’t help product image, he notes. “We’re working closely with Bayer to make sure that doesn’t happen again, and we’re telling customers who order LibertyLink seed to purchase their herbicide right away.”

According to Cotie, last season’s herbicide shortage was due to an increase in product demand worldwide. “We’ve got our plants running at full capacity now, so there should be adequate supplies in the 2013 season.”