Dicambatolerant field flag

Dicamba-tolerant crops soon to be a reality

Monsanto reached a milestone last month in its bid to register dicamba-tolerant (Xtend) soybeans and cotton. The USDA comment period was officially opened. According to Monsanto, cotton deregulation is scheduled for a 2015 release. Soybeans could be available at that same time depending on worldwide acceptance of the GMO trait. Monsanto estimates 2016 as a release date of Xtend soybeans. There are still a lot of regulatory hoops to jump through.

In Arkansas, the pesticide committee of the State Plant Board has been working on the anticipated state registration of Roundup Ready Xtend for several months. After much careful thought and testimony they have decided to recommend that the use of dicamba be allowed in 2015, if registered, under the use guidelines of the federal label with the addition of some language about buffers and wind direction. Much of this still depends on full registration approval and full State Plant Board approval. Once it is registered, be sure to read and follow all state and federal rules.

The concern with dicamba is off-target movement and volatility, primarily to non-dicamba-tolerant soybeans. Although some research has been done on lower volatility versions of dicamba, the initial registration request from Monsanto is for dicamba plus a drift retardant. Further down the line there are other formulations of dicamba and technologies being evaluated for Xtend crops. XtendiMax is dicamba plus a proprietary product called vapor grip that reduces volatility and Xtend herbicide is XtendiMax plus a formulation of glyphosate. This new technology also includes a process for cleaning tanks and booms.

In addition to controlling pigweed and horseweed which are resistant to glyphosate, the ability to use dicamba will also improve the control of weeds such as morningglory, sicklepod, redvine and trumpetcreeper when applied in-season. In particular, this technology will have a fantastic fit on redvine and trumpetcreeper acres.

Another big advantage will come with a zero-day plant-back interval. That is, you can make a burndown application of dicamba immediately prior to or after planting Xtend crops with no injury.

Dicamba also provides some residual control. Some research has shown that under low rainfall conditions, dicamba can improve residual weed control when tank-mixed with products like Dual, Warrant or Zidua, which require rainfall for activation.

This technology comes with the significant risk of off-target movement, especially to non-dicamba-tolerant soybeans (cotton is more tolerant to dicamba than soybeans). It is important to note that Enlist soybeans will not tolerate dicamba. Most drift on soybeans will likely be cosmetic, cupped leaves alone. It probably won’t hurt yields, but may cause consternation — more fields for me and the State Plant Board to look at. Even though yields are not hurt, an applicator could still be fined for off-target movement.

With this and other new herbicide-tolerant crops there is going to be both risk and reward, but with no new modes of action in sight and the current over-reliance on herbicides like glufosinate (Liberty) and the PPO inhibitors (Valor, Flexstar, Blazer, Cobra, etc.), we need new options for weed control.

In the Flag the Technology program, the color for dicamba will be black. Xtend is glyphosate plus dicamba and, therefore, a black and white checkered flag will signify an Xtend technology field.

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