Wineries in Texas are worried that federal approval of two highly volatile and drift-prone herbicides used on neighboring genetically modified (GMO) cotton fields will cause widespread damage to their vineyards, The Texas Tribune details.

Dicamba damage on a grape leaves. Uky.edu

The herbicides in question are Monsanto's dicamba-based XtendiMax with VaporGrip Technology, which was approved in November by the U.S. Environmental Protection Agency (EPA), and Dow AgroSciences' 2,4-D-based Enlist Duo, which the EPA also proposed to register for use on GMO cotton seeds. Enlist Duo is already used on GMO corn and soybean crops in 15 states.

"The approval of these formulations will wind up affecting every vineyard up there," explained Paul Bonarrigo, a Hale County vintner who believes that his withering grapevines have been damaged by the illegal spraying of dicamba and 2,4-D on nearby cotton farms. Bonarrigo believes that the state's $2 billion wine industry is in jeopardy.

The debacle is yet another chapter in the expanding issue of herbicide-resistant weeds, or superweeds, that have evolved to resist the herbicide glyphosate, or Roundup. In response to weeds such as pigweed that have infested farms across the U.S., agribusinesses such as Monsanto and Dow have developed ever stronger weedkillers to help farmers.

As noble as that might sound, Monsanto was especially criticized when it decided to sell its dicamba- and glyphosate-resistant soybean and cotton seeds to farmers before securing EPA approval for the herbicide designed to go along with it. Bollgard II XtendFlex cotton was introduced in 2015 and Roundup Ready 2 Xtend soybeans was introduced earlier this year.

Without having the proper herbicide, cotton and soy farmers resorted to spraying older versions of dicamba on their crops. But dicamba, as well as the herbicide 2,4-D, are extremely prone to drift, meaning the chemicals can be picked up by the wind and land on neighboring fields that cannot withstand the chemical damage. When exposed to the herbicide, leaves on non-target plants are often left cupped and distorted.

Researchers from Ohio State University published a study in September showing that herbicide spray drift from the 2,4-D and dicamba can severely damage wine grape plants near agronomic crops.

Common leaf injury symptoms observed in vines 42 d after being treated with (a) glyphosate, (b) 2,4-D, (c) dicamba, and (d) nontreated controlOhio State University

Although Monsanto said it warned farmers against illegal dicamba spraying, this past summer, dicamba drift caused 10 states to report widespread damage on thousands of acres of non-target crops such as peaches, tomatoes, cantaloupes, watermelons, rice, cotton, peas, peanuts, alfalfa and soybeans.

Last month, Missouri's largest peach grower filed a lawsuit against Monsanto over claims that dicamba drift damaged more than 7,000 peach trees on the farm, amounting to $1.5 million in losses. This year, the farm said it lost more than 30,000 trees, with financial losses estimated in the millions.

Regulators assured to The Texas Tribune that the new pesticides are less likely to vaporize and drift, and the risk of damage will lessen if farmers follow safety precautions.

"I don't see this as being any more of an issue than what we have today," Steve Verett, executive vice president of the Plains Cotton Growers, told the publication. "I understand there are other sensitive crops as well. No matter what the product is or the farmer that's spraying, they need to make sure that the product they're spraying stays on their farm."

Kyel Richard, a spokesman for Monsanto, added that the company has conducted training exercises and education efforts to minimize "the opportunity for movement off- site and ensuring those herbicides are staying on target and controlling those weeds on the field that they're intended for."

State wineries, however, are worried that with the EPA's approval, use of dicamba and 2,4-D will expand to include 3.7 million acres of cotton fields.

"I could see it basically killing the [wine] industry, honestly," Garrett Irwin, owner of Cerro Santo vineyard in Lubbock County, countered. "If we get the levels of damage that I'm afraid we'll get, vineyards will not be able to recover or produce grapes at any sustainable level, and we're just going to have to go away."

Irwin also commented that cotton and soy farmers are likely to stick with old dicamba and 2,4-D herbicides because the new formulations are more expensive. Additionally, farmers have to upgrade their equipment with anti-drift nozzles to use the new products.

"I honestly don't think farmers will buy the new formulations when older labels that cost less are available and just as effective as the new labels," he said. "In short, I think farmers will buy generic chemicals without the additives to save money because the cotton won't know the difference."

And if they do buy the new herbicides, there will still be some farmers who "will do nothing to correct for negligence in spraying," Irwin said.

Pheasant Ridge Valley winery owner Bobby Cox told The Texas Tribune that he is worried that cotton farmers will have no choice but to switch to the new seeds system.

Cox said that 2,4-D drift in 2015 caused the amount of sugar in his grapes to be about 5 percent less than ideal.

"It will be catastrophic not only to vineyards but to oak trees, to pecan orchards, to shrubs," Cox said. "If they apply the amount of 2,4-D that they did Roundup and are equally irresponsible with that, it will kill everything green up here. I wish people would understand how important wine growing is for this area, how wonderful of a crop it is on the High Plains. It would be a shame to lose it when we're starting to get recognized."

Not only that, environmental experts worry about dicamba's threat on biodiversity and wonder if pesticide-makers are just creating another cycle of herbicide resistance.

"Once again the EPA is allowing for staggering increases in pesticide use that will undoubtedly harm our nation's most imperiled plants and animals," said Nathan Donley, a scientist with the Center for Biological Diversity, after the EPA approved the Xtend weedkiller. "Iconic species like endangered whooping cranes are known to visit soybean fields, and now they'd be exposed to this toxic herbicide at levels they've never seen before."

"We can't spray our way out of this problem. We need to get off the pesticide treadmill," he continued. "Pesticide resistant superweeds are a serious threat to our farmers, and piling on more pesticides will just result in superweeds resistant to more pesticides. We can't fight evolution—it's a losing strategy."