Glyphosate resistant weeds are a growing problem for Nebraska corn and soybean growers. For example, it's estimated Nebraska has around 2.2 million acres infested with glyphosate-resistant common waterhemp.

However, growers now have some new tools in the toolbox to control resistant weeds. At an upcoming Weed Management Field Day, growers will get a look at some of these new tools, as well as research updates on some of the latest technologies available. The field day will be held from 8 a.m. to 1 p.m. June 29 at the South Central Ag Lab near Clay Center.

NEW TOOLS THE WAR ON WEEDS: At an upcoming Weed Management Field Day, growers will get a look at some of the new tools in the toolbox to help control resistant weeds, as well as research updates on some of the latest technologies available. "The main purpose of the field day is to show the growers multiple herbicide tolerant soybeans coming to the market," says Amit Jhala.

"The main purpose of the field day is to show the growers multiple herbicide tolerant soybeans coming to the market," says Amit Jhala, University of Nebraska-Lincoln Extension weed management specialist.

This includes research on Monsanto's Roundup Ready 2 Xtend soybeans with tolerance to dicamba; Dow Agroscience's Enlist soybeans with tolerance to glyphosate and 2,4-D choline; Bayer CropScience's Balance Bean soybeans with tolerance to Balance Flexx, glyphosate, and Liberty; DuPont Pioneer's Bolt soybeans with tolerance to ALS-inhibiting herbicides; as well as herbicide programs for conventional soybeans.

"This is what the future of weed control will be," Jhala says. "It is important to know what herbicide programs should be used in new multiple herbicide tolerant crops for best control of resistant weeds and achieve a high level of crop safety."

BROAD-SPECTRUM WEED CONTROL: In recent years, Jhala has been trialing several new herbicide technologies, including Enlist Duo and Roundup Ready 2 Xtend. "All these new technologies are great, but relying on only one technology creates a problem," he says. "I think with the right practices, we can still get pretty good broad-spectrum weed control and make sure we don't end up having more herbicide-resistant weeds in the future."

Part of the tour will include weed control projects in corn – including Enlist corn, as well as new herbicides such as Syngenta's Acuron, FMC's Anthem Maxx, and Bayer CropScience's DiFlexx Duo. "These new herbicides are a mixture of already-existing herbicides, but they can provide broad-spectrum weed control if applied as per label direction and weeds present in the field," Jhala says.

Another project focuses on DuPont's Inzen – a sorghum trait tolerant to ALS-inhibiting herbicides like nicosulfuron (Zest).

Jhala has been trialing Enlist Duo over the last two years. Pending EPA approval, he notes 2,4-D is very effective at controlling giant and common ragweed. "If growers use multiple modes of action in their herbicide programs, make a pre-emergence application, followed by a post-emergence application of Enlist Duo in corn and soybeans, we have seen good control of common lambsquarters and common waterhemp," Jhala says.

For the last three years, Jhala has also researched Roundup Ready 2 Xtend soybeans. "Every year we have seen very good control and great tolerance in soybeans when we apply dicamba and glyphosate in a post-emergence application," he says. "Because dicamba can provide about two weeks of residual activity, that will also help with controlling some hard-to-control broadleaf weeds like common waterhemp, velvetleaf, marestail, and common lambsquarters."

Jhala cautions that multiple herbicide tolerant crops, while an effective tool, aren't a silver bullet. The same best management practices needed to prevent glyphosate resistance from developing are needed when using these new technologies – that is, including herbicides with multiple modes of action and overlapping residuals. "All these new technologies are great, but relying on only one technology creates a problem," he says. "I think with the right practices, we can still get pretty good broad-spectrum weed control and make sure we don't end up having more herbicide-resistant weeds in the future."

Learn more in an upcoming Nebraska Farmer print article, and by attending the Weed Management Field Day. Register for the field day at agronomy.unl.edu/weedresistmgt. The field day site is near Clay Center: 4.5 miles west of the Highway 14 and Highway 6 Intersection, or 12 miles east of Hastings on Highway 6. For additional information, contact Jhala at [email protected].