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Serving: United States
red combine head harvesting soybeans Dave Hansen, U-M
CART BEFORE HORSE: Minnesota Soybean is cautious about a new soybean variety offered for 2019. LibertyLink GT27 is tolerant to glyphosate and a new, yet-to-be-EPA-approved HPPD/Group 27 herbicide. EPA approval might come by end of the year.

Herbicide use concern for ’19 LibertyLink soybeans

EPA has yet to approve a HPPD herbicide for use on the new product, which could cause confusion and misuse among growers.

Soybeans growers face another scenario where they must pay attention to technology approvals.

Leadership at the Minnesota Soybean Research and Promotion Council cautions farmers about correct herbicide use on the new LibertyLink GT27 soybeans in 2019.

In July of this year, Bayer Crop Science and MS Technologies released LLGT27, which is tolerant to both glyphosate and a new, yet-to-be-EPA-approved HPPD/Group 27 herbicide.

Currently, LLGT27 is labeled for herbicides containing glufosinate, such as Liberty, and glyphosate, such as Roundup. However, LLGT27 does not have a legal label for HPPD products such as Balance, Callisto and Laudis.

David Kee, MSRPC director of research, noted in a blog that soybean growers need options in the weed-control battle.

“However, much like with the dicamba rollout, the GT27 genetic event comes with an issue of having a potential solution without legally labeled HPPD herbicide available for use,” he wrote.

Tolerance exists in LLGT27 for only one HPPD active ingredient: isoxaflutole (IFT).

BASF officials have said that exposure of any other HPPD compounds might, depending on the compound, produce significant damage to the LLGT27 soybeans, Kee noted. BASF now owns the LibertyLink technology, having bought it from Bayer in 2017.

EPA approval of the isoxaflutole compound is anticipated to occur by late December, Kee added. Once approved, the BASF IFT product would be labeled only for preemergent application.

IFT restrictions in Minnesota
Josh Stamper, director of the pesticide and fertilizer management division at the Minnesota Department of Agriculture, says he appreciates the proactive approach of state soybean growers’ organization in stewarding the technology.

“The HPPD tolerance in the GT27 event represents a powerful tool for farmers that are battling herbicide resistant weeds,” he says. “However, the deregulation of new genetic traits in crop seeds does not always coincide with the legal federal registration of the herbicide that the crop is resistant to. For example, the dicamba saga started in the mid-South, with dicamba-tolerant cottonseed being released before there was a dicamba product labeled for use on dicamba-tolerant soybeans.”

Stamper points out that Minnesota, along with Wisconsin and Michigan, required additional environmental testing from the IFT registrant before it could be registered for use in those states.

“This was because the product can very rapidly impact groundwater if used on sandy soils, or in areas of the state where surface runoff can rapidly become groundwater,” he says.

Accordingly, IFT is not labeled for use in all Minnesota counties. Balance, a common IFT herbicide, can be used neither north of I-94 nor in 10 southeastern counties — Dakota, Dodge, Fillmore, Goodhue, Houston, Mower, Olmsted, Rice, Wabasha and Winona — where groundwater is vulnerable due to the fractured limestone geology.

Stamper says MDA officials have spoken with seed and chemical companies and the Minnesota Crop Production Retailers to make sure that growers know what the law says when it comes to using these new tools responsibly.

“Coupling compliance assistance, education and open communication between registrants, agribusiness, the farm community and regulators is the key to making sure that everyone understands what ag chemical tools are appropriate for each job,” Stamper says.

Proper use to be defined
Jeff Gunsolus, University of Minnesota Extension weed scientist, concurs that LLGT27 soybeans offer growers new flexibility in using glyphosate or glufosinate in the same field. However, the real question is how best to manage the timing of the products based on weed species, resistant biotypes and weed emergence patterns.

“If isoxaflutole registration is approved, the next concern is to make sure it is used properly — only as a preemergence residual herbicide — and also to make sure that the end user understands that other HPPD herbicides Impact, Callisto and Laudis are not used on this soybean variety, as it lacks residue clearance if directly applied or drifts to untraited soybean varieties and is likely to induce significant crop injury,” Gunsolus says.

He added that, due to waterhemp, common and giant ragweed expressing resistance to several groups of herbicides including glyphosate, a simple switch to Balance or Liberty in soybeans without a more robust herbicide resistance management plan has the potential to shorten the durability of this newer variety and herbicide combination.

“Remember that the HPPD herbicides have been in use for a number of years in corn, and some of these same weed species may have already undergone some level of selection for herbicide resistance,” Gunsolus says.

For more details on herbicide resistance management strategies, he suggested U-M's herbicide resistance management webpage.

Zero tolerance for residues
Kim Nill, Minnesota Soybean’s director of market development, says another possible issue pertaining to growing LLGT27 has been raised: HPPD residue levels in beans.

“As there is currently no legally labeled HPPD herbicide for soybeans, a maximum residue level for HPPD compounds in harvested soybeans would be zero,” Nill says.

BASF officials have said that import approvals have been obtained from the Philippines, China and the European Union.

Discovery of illegal pesticide residues in the grain, regardless of source, would subject the crop to condemnation, Nill notes. All grain — not only that from the treated crop — stored with it would be subject to condemnation. The applicator would be subject to penalties for violating the pesticide label. Given the current trade issues, misuse of this technology could result in substantial economic damage to soybean growers.

Good option for growers
Adam Spelhaug, agronomist with Peterson Farm Seeds, Harwood, N.D., said his company is excited to market LLGT27.

“It brings some new genetics and a different stack of herbicide tolerance we haven’t had before,” Spelhaug says. “The ability to spray Liberty or glyphosate is a great option for our growers.”

He notes, as did others, that no HPPD herbicides have been approved yet by EPA.

“Our seed tags reflect this,” he adds. “Farmers have always had to abide by labels, and this is no different.”


TAGS: Crops
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