LITTLE ROCK, Ark. — The Arkansas State Plant Board has approved regulations on the use of the herbicides 2,4-D and dicamba, including restrictions based on wind speed, location of nearby susceptible crops and droplet size.

The conditions placed on the products were necessary in order to protect sensitive crops from off-target drift, said Terry Walker, agency assistant director for the board.

“The board recognized the existence of new technologies, technologies that are needed out there because of the weed situation,” Walker explained. “These were the regulations everybody thought were a good attempt to afford protection.”

Under the regulations approved at the board’s Dec. 18, 2014, meeting, wind speed must not exceed 10 mph during an application of either herbicide, and those winds must be blowing away from nearby sensitive crops. The board is requiring a median droplet size of greater than 400 microns for Monsanto Co.’s dicamba and 300 microns for Dow AgroSciences’ 2,4-D product. The tank mixes should not increase the driftable fines – those less than 200 microns – by more than 10 percent over use of the product alone, Walker said.

The board also created a buffer zone of 400 feet between the application of Monsanto’s M1691 and sensitive crops. All the restrictions take effect immediately, though the board is open to hearing from the companies, farmers or neighbors if they have a problem with any of the regulations, he said.

For more than two years, the board has heard testimony from representatives of Dow and Monsanto, plant and weed experts, and others with an interest in the process. While the issue is settled for now, it may be revisited after the new technologies are in use, Walker said.

“When you have a process and a difficult issue to face, it’s always stressful,” Walker said. “You want to give everyone an opportunity to have a say, and it’s very satisfying to finish and come up with regulations that are fair. If everything succeeds, we probably won’t hear from anyone, but if they fail, we’ll surely hear about that.”

The board’s 18 members represent various segments of the agriculture industry and, as such, had differing opinions on the restrictions eventually approved by the board, Walker noted.

“I don’t think it would be reasonable to expect 18 people to agree on everything,” he said. “There’s varying levels of agreement and levels of support on any action. There was some degree of reservation from some of our members.”

Monsanto and Dow officials have said they’re hoping to make available genetically engineered plants resistant to dicamba and 2,4-D in the next year or so. State pesticide boards don’t have a role in deregulating the plants, which is done through the USDA. The U.S. EPA is reviewing the use of dicamba and 2,4-D and is assessing the potential for environmental and human risks associated with their use.

Pending approval by USDA and EPA, Dow officials have said they expect a 2015 launch for Enlist corn and soybeans and a 2016 start for Enlist cotton. Monsanto is planning a limited commercial launch for its cotton product this year. For soybeans, the company anticipates a full commercial start in 2016 with some trials this year.

Monsanto said in a statement it has been working the last 10 years to develop and bring to market its Roundup Ready Xtend Crop System and respects the process and decision made by the plant board.

Also in a statement, Dow said the plant board was diligent in its review of new technologies. The board’s “balanced approach reflects an understanding of the struggles Arkansas farmers are facing in controlling weeds in their fields and the need for a new tool to combat those weeds,” the company noted.

The chair of the Save Our Crops Coalition (SOCC) is satisfied with the board’s action. “I still have concerns, but if you follow these recommendations, you will not cause off-target movement,” Steve Smith said. “I don’t think we’re going to stop that technology from happening nor do we want to. But under these rules, you will not cause injury to your neighbor.”

During a public hearing before the board announced its decision, Smith said Dow and Monsanto have had different responses to concerns over such issues as wind speed and direction, and the volatility of older generic products. Smith is also director of agriculture with Elwood, Ind.-based Red Gold.

In September 2012, Dow and the SOCC reached an agreement that said, in part, the label for Dow’s Enlist Duo would state the product may not be applied toward sensitive crops at any wind speed. The company also pledged to educate farmers and applicators on the proper use of Enlist and to use its laboratories and field staff to be sure its chemicals were applied correctly.

Monsanto, meanwhile, hasn’t dealt with the concerns, Smith noted, “leaving enormous exposure to not only crop injury but also to complete crop loss when an off-target event would occur since no tolerances are in place on most food crops.”

SOCC was formed in 2012 over concerns with off-target damage from 2,4-D and dicamba. The primary concern of the organization has been the tendency for synthetic auxins to volatilize, or for their active ingredients to evaporate.