Game-changers: new herbicides

This past fall when USDA deregulated Enlist corn and soybeans and the U.S. EPA registered Enlist Duo herbicide, Dow AgroSciences announced it would conduct a stewarded introduction of Enlist corn seed in the U.S. in 2015. It was a game-changer in several ways. Adding to the excitement will be Monsanto’s Roundup Ready 2 Xtend soybean system, Bayer’s Balance GT Soybean System and Dow’s Enlist s

Game-changers: new herbicides

This past fall when USDA deregulated Enlist corn and soybeans and the U.S. EPA registered Enlist Duo herbicide, Dow AgroSciences announced it would conduct a stewarded introduction of Enlist corn seed in the U.S. in 2015. It was a game-changer in several ways. Adding to the excitement will be Monsanto’s Roundup Ready 2 Xtend soybean system, Bayer’s Balance GT Soybean System and Dow’s Enlist soybean system, all likely to hit the market in 2016.

While we will soon have these new tools to fight herbicide-resistant weeds, we’ll also be entering a new realm of regulatory requirements and scrutiny pertaining to use and stewardship of new biotech events. From a global perspective, the approval, launch and use of these technologies could generate more interest, attention and scrutiny than the advent of Roundup Ready crops did back in the late 1990s. While this may sound a little unnerving to farmers and others involved in agriculture, I think in the long run it will be a good thing; we’re poised to change the game ourselves.

We’ve experienced a lot of success with, and learned some tough lessons from, the use of previous biotech events. Contending with issues like grain recalls and rejections, pollen and pesticide drift, public concerns about GMO safety, and the rapid evolution of herbicide-resistant “superweeds,” to name a few, has been challenging, but has gotten us to a point where we should be able to implement safe and sustainable stewardship of these new events.

Stewardship of new traits

We’ve talked about dicamba beans, Balance beans, and 2,4-D corn and beans for several years now; a lot of growers are looking forward to these technologies to help control some of our toughest weeds. While it looks like we’ll wait another season for dicamba and Balance beans, we’ll get a good look at the 2,4-D systems in 2015. To avoid trade disruptions, Dow will manage its stewarded introduction of Enlist corn seed in the U.S. in 2015.

Participating farmers must adhere to a set of stewardship protocols and requirements. For example, isolation areas adjacent to Enlist cornfields will be required, and third-party audits will be conducted. Also, growers must agree that the grain will be used for livestock feed so it doesn’t leave the farm. The 2015 plan for Enlist soybeans has Dow conducting a Field Forward program to provide a limited number of growers the chance to grow seed beans for Dow in anticipation of commercial launch in 2016.

“Ground rules” fit the application label language pretty well, because Enlist Duo can only be applied from the ground; no aerial applications allowed. EPA also spelled out other guidelines to help keep drift to a minimum.

A topic we’ve discussed in meetings the last couple of years is the setback, or buffer. A common fear among growers and applicators was that the required buffer would be quite large or restrictive, severely limiting the acres in each field that could be treated. You can estimate your own buffers after reading the label guidelines, but it looks like something we can handle.

Follow new ground rules

The intent of the label language is to require a 30-foot in-field buffer at the downwind edge of the field. For example, if the wind is blowing in a southern direction, the buffer would be the 30-foot section of the corn or soybean field to be treated at the southern edge of the field. You must maintain a 30-foot downwind buffer (in the direction in which the wind is blowing) from any area except:

roads, paved or gravel surfaces

planted agricultural fields (except crops listed under “Susceptible plants” )

agricultural fields that have been prepared for planting

areas covered by the footprint of a building, shade house, greenhouse, silo, feed crib, or other man-made structure with walls or roof

To maintain the required downwind buffer zone, the following must be done:

Applicators must measure wind direction before the start of any swath that is within 30 feet of a sensitive area.

No application swath can be initiated in, or into an area that is within 30 feet of a sensitive area if the wind direction is toward the sensitive area.

Other critical requirements include:

Check nozzle type and allowable pressure specified on the label. I came up with about 75 nozzle and psi combinations that would work. No doubt there will be more as we get further down the line.

Do not apply at wind speeds greater than 15 mph.

Refer to the state’s sensitive crop registry before making an application.

Do not apply under circumstances where spray drift may occur to food, forage or other plantings that might be damaged.

At time of application, wind cannot be blowing toward adjacent commercially grown tomatoes and other fruiting vegetables or grapes.

Proactive label language

There are also some strong suggestions that come along in the package. I’ll summarize a few because they are important concepts you may not have noticed in a label before.

Scout fields before application.

Use full rates at correct weed size for your toughest weeds.

Scout fields after application.

Report any nonperformance to Dow AgroSciences.

If resistance is suspected, treat escapes with non-group 4 or 9 herbicide, or use nonchemical methods to prevent seed production.

Dow and EPA include additional sound advice in the label for Enlist Duo. You’ll see sections describing best management practices (BMPs):

Use a broadspectrum soil-applied herbicide.

Implement sequential applications with alternative sites of action.

Rotate with non-group 4 and 9 herbicides.

Incorporate nonchemical practices.

Clean equipment after working in infested field.

Avoid using more than two applications in a season unless other herbicides are included.

Manage weeds in and around fields.

These are all concepts we’ve talked about ever since weed resistance really started taking off. There are many more BMPs in the label information and likely in the grower agreement. They are targeted at fending off weed resistance and enhancing herbicide trait stewardship — the protection of the long-term efficacy of trait technologies.

McGrath is the ISU Extension field agronomist at Harlan in western Iowa. Contact him at [email protected].

Look at the bottom line

Acres with resistant weeds roughly doubled in the U.S. between 2009 and 2013; we’re now pushing the 70 million-acre mark. Herbicide-resistant weeds cost U.S. farmers $2 billion annually, a number that keeps climbing as resistant weeds spread across more acres. This quote from the Enlist Duo specimen label I saw sums it up: “The continued availability of this product depends on successful management of the weed resistance program.” I’d guess it may also depend on mitigating off-target movement as well.

With 70 million acres of resistant weeds costing farmers $2 billion, with that much on the line, we need continued availability of these emerging technologies. We need to be on top of our stewardship game so we can maintain the efficacy and safety of, and access to, these game-changers. — Clarke McGrath

This article published in the January, 2015 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2015.

Weed Control

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