Here’s a brief analysis of herbicide-resistant crops from Bill Curran and Dwight Lingenfelter, Penn State Extension weed control specialists.

Xtend soybeans
Roundup Ready 2 Xtend soybeans (Monsanto) have been developed to allow preemergence or postemergence applications of dicamba (the active ingredient in Clarity). These dicamba-tolerant varieties are also stacked with the Roundup Ready trait.

Xtend seed was approved for use in 2016. But major exports weren’t yet approved by soybean planting time. A few fields of the seed were planted primarily in the South, and dicamba products were illegally used and had major drift and off-target injury problems.

On Nov. 9, Monsanto received federal approval for a dicamba-containing (Clarity, DGA-formulation) product called Xtendimax with “VaporGrip” technology to reduce volatility. So that hurtle is cleared.

Engenia, BASF’s dicamba product, is now labeled for use on Xtend soybeans. DuPont’s Fexapan is likely to be.

All three products face restrictive labels due to drift risks. How restrictive? Applications can’t occur if wind is blowing toward specific crops such as tomatoes, vine crops, grapes and others. The applicator is responsible for any drift to off-target sites, and more.

Guidelines for using Xtendimax as a burndown application are vague and can change periodically as new information is acquired. Updates will be posted online by Monsanto at www.xtendimaxapplicationrequirements.com.

Several states already have registered Xtendimax for use on Xtend soybeans. Pennsylvania approval is likely.

Curran and Lingenfelter see value particularly in a burndown for marestail control. They’re less excited about in-crop applications, and would prefer to first learn from experiences in other states and regions during 2017.

Enlist soybeans
Enlist soybeans (Dow AgroSciences) is a genetically modified soybean line resistant to glyphosate, 2,4-D and glufosinate. And, a new 2,4-D choline formulation is being developed to offer ultralow volatility, reduced drift and decreased odor plus improved handling. It’s referred to as Colex-D technology.

Enlist Duo is the first premix to emerge. It’s a combination of 2,4-D choline plus glyphosate. No other 2,4-D formulations are expected to be labeled for use over the top on Enlist crops this year.

At this writing, Enlist soybeans are still awaiting export. Exports to China and the European Union are the biggest holdups. It’s likely the situation won’t be resolved in time for the 2017 growing season. But since this is an ever-changing process, registration could happen at any time.

Update on HPPD-tolerant beans
HPPD-tolerant soybeans (Bayer CropScience and Syngenta) are being developed independently to allow in-crop applications of HPPD-inhibitor herbicides (Balance Bean and Callisto). These varieties will likely be stacked with glyphosate- and glufosinate-resistant traits.

Bayer’s Balance GT soybean system is expected to be launched soon. Syngenta’s MGI soybeans are targeted for later in the decade.