Or, it could do both.

"Enlist," entering the final stages of regulatory approval, has become the latest flashpoint in the debate about the risks and rewards about farm technology. With a deadline to submit public comments on Dow's proposal at the end of this week, more than 5,000 individuals and groups have already weighed in. Dow Agrosciences, a unit of Dow Chemical Co, hopes to have the product approved this year and released by the 2013 crop.

The corn itself is not the issue -- rather it is the potent herbicide chemical component 2,4-D that is the center of debate.

The new corn is engineered to withstand liberal dousings of a Dow-developed herbicide containing the compound, commonly used in lawn treatments of broadleaf weeds and for clearing fields of weeds before crops like wheat and barley are planted.

Enlist is the first in a planned series of new herbicide-tolerant crops aimed at addressing a resurgence of crop-choking weeds that have developed resistance to rival Monsanto's popular Roundup herbicide. It is part of an expanding agricultural arsenal advocates say is key to growing enough food to feed a growing global population.

But while 2,4-D has a long history of effective use, the chemical's volatile nature also worries environmentalists because winds, high temperatures, humidity can cause traditional forms of the herbicide to migrate from farm fields where it is sprayed to wreak havoc on far-off crops, gardens, and trees that are unprotected from the invisible agent.

Environmentalists are pushing the government to pause before opening the door to what they say could be a destructive turn.

Opponents include some specialty crop farmers who fear 2,4-D herbicide use could cause widespread damage to crops that are not engineered with a tolerance to it. It is so potent that its use is tightly restricted in some areas and at certain times of the year in some U.S. states.

"It is a major issue for farm country," said John Bode, a lawyer for a coalition of farmers and food companies seeking regulatory restrictions or rejection of Dow's plans.

"Massive amounts of 2,4-D... can cause major changes, threatening specialty crops miles away," said Bode, an assistant Secretary of Agriculture in the Reagan administration.

The financial stakes are high as well. Dow projects a "billion dollar value" in a product line that is its biggest challenge yet to the dominance of top seed company Monsanto's revolutionary Roundup herbicide and its genetically modified "Roundup Ready" seeds. Dow hopes to expand Enlist into soybeans and cotton.

Where Roundup once killed weeds easily, experts say that now, even heavy use of the herbicide using the key chemical glyphosate often fails to kill "super weeds."

NEW HERBICIDE TEMPERS 'DRIFT'

Some weed scientists are supportive of Enlist. In the southern third of Illinois, prime corn-belt country, infestations of the invasive water hemp weed have doubled each year over the past three years, according to Bryan Young, weed scientist at Southern Illinois University.

"The de-regulation of Enlist herbicide-tolerant corn will expand grower options for controlling problematic weeds and has proven in my research to be effective as such," Young wrote to the USDA in a letter supporting Dow's application.

Dow officials say they are aware of the problems with 2,4-D "drift" and volatility, and that the new herbicide has been formulated to reduce those factors dramatically.

Dow says that if farmers use the new Dow version of 2,4-D properly, drift is reduced about 90 percent, and tests show the new product has "ultra-low volatility."

Even many opponents of Dow's new herbicide say it is an improvement of generic rivals using 2,4-D. But they say Dow's version will be expensive enough that many farmers will probably buy cheaper generics to spray on the 2,4-D-tolerant corn.

Dow acknowledges that lure, but says it will work to steer farmers to its brand.

"I don't think you can ever guarantee it, but we are doing all we can to try to incentivize people and educate people," said Tom Wiltrout, Global Strategy Leader for Seeds and Traits at Dow. "We were worried too. That was one of the big debates we had. Chemistry is the key. We think we've got an answer."

David Simmons, an Indiana farmer who grows corn and soybeans but also runs a vineyard and winery, says his young grapevines have suffered significant damage from drifting 2,4-D applications at neighboring farms, forcing him to fight to recover damage claims from fellow farmers' insurance carriers.

"I'm faced with looking five years down the road. Is it even going to be profitable to grow grapes if I continue to get this damage every summer?" Simmons said.

Due to the already-known effects from "drift," opponents have requested that some form of an indemnity fund be established to pay loss claims from farms damaged by inadvertent 2,4-D applications. Dow has opposed that safeguard.

HIGH STAKES

Opponents have flooded the U.S. Department of Agriculture with petitions and pleas for either rejection of Dow's new corn, or strict regulation before use of 2,4-D is expanded into millions of acres in the U.S. agricultural heartland. More than 90 million acres of corn alone will be planted in 2012.

Last week, the Save Our Crops coalition representing more than 2,000 U.S. farmers filed legal petitions with the USDA and the Environmental Protection Agency demanding the government scrutinize Dow's plans more closely. The group has said it could file a lawsuit to try to stop the new type of corn.

Steve Smith, director of agriculture at Indiana-based Red Gold, the world's largest processor of canned tomatoes, calls the 2,4-D issue a "ticking time bomb."

"We are all producers and people who have no problem with new technology. But we see this new piece of it having side effects that we don't think people have adequately thought of," said Smith.

Others fear Enlist and 2,4-D may only be only the beginning of a new wave of dangerous farm chemicals. Chemical giant BASF and Monsanto plan to unveil by the middle of this decade crops tolerant to a mix of the chemicals dicamba and glyphosate.

This increasing use of chemicals will only spell worse weed resistance in years to come, warn weed scientists and environmentalists.

"It's a chemical arms race," said Andrew Kimbrell, a lawyer at the Center for Food Safety opposed to the new crop systems. "It's a scary scenario. We won't be able to do anything with these weeds other than use machetes."

Instead of using more chemicals in order to plant corn on the same field year after year, U.S. farmers should be rotating crops more, a technique proven to challenge weed resistance, many weed scientists say.

Dow says that while Enlist farmers' best option for now, it will not be the only long-term solution for weed resistance.

"There is no silver bullet here," said Joe Vertin, Dow's global business leader for Enlist.

(Reporting By Carey Gillam; Editing by David Gregorio)

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