California farmer Erik Freese pulls down a healthy ear of corn that has been genetically engineered to produce its own pesticide. He says genetic engineering has helped him to farm more sustainably.

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A new food fight is stirring in California. This November, voters there will decide whether to require labels on foods with genetically engineered ingredients. If the initiative passes, its effects would likely be felt across the U.S., changing the way producers package everything from soda to cereal.

Capital Public Radio's Kathleen Masterson reports from Sacramento.

KATHLEEN MASTERSON, BYLINE: It's a hot sunny afternoon outside a Sacramento grocery store. Holly Brewer is loading plastic bags of food into her car. She grows some of her own food in a backyard garden and says consumers deserve to know what they're eating.

HOLLY BREWER: And I personally probably wouldn't want genetically engineered products because, I don't know, I just hear so many things about how they could affect you.

MASTERSON: Brewer isn't the only one who's concerned. Paul Towers with the Pesticide Action Network says hundreds of thousands of Californians signed a petition to get the labeling initiative on the ballot.

PAUL TOWERS: When we look at nutrition facts or when we look at ingredients, that information allows us as consumers to make choices. This is one additional piece of information, a little bit of additional ink that allows consumers to make better choices.

MASTERSON: If California's Proposition 37 passes, somewhere on the front or the back of the food's packaging it would have to say if the product contains or may contain genetically engineered ingredients. In the United States, the vast majority of corn, soybeans, canola and sugar beets are genetically engineered. Those ingredients are in everything from salad dressing to ice cream.

ERIK FREESE: So you'll see if the corn ear worm got in here, it would just eat in here, and it would open this up, put a pretty good-sized hole in here, open the plant up for disease.

MASTERSON: Fifth generation California farmer Erik Freese pulls down a healthy ear of field corn that has been genetically engineered to produce its own form of pesticide. He points to the robust yellowish kernels, which, he says, without this kind of biotechnology would be vulnerable to pests.

FREESE: And then the worm would eat most of these - the soft kernels in here.

MASTERSON: Freese says genetic engineering has helped him to farm more sustainably. He says he sprays pesticides fewer times per season, and he doesn't have to do as much tilling with his tractor to kill weeds, which saves fuel and reduces emissions. If this biotechnology were really dangerous, says Freese, then the measure should also require restaurant food and meat that was fed genetically modified crops to be labeled. The measure doesn't go that far. But California rice farmer Grant Lundberg of Lundberg Family Farms says if there's nothing wrong with genetic engineering, then food companies shouldn't be afraid to label it.

GRANT LUNDBERG: I've been raised to listen to my consumer. This is what they want. You may not agree with it, but that's the market. You have to come to terms with that.

MASTERSON: But not all customers, even health-conscious ones, are asking for the labels. Back at the grocery store, Guy Burdick says he and his wife try to feed their kids healthy food.

GUY BURDICK: We check the labels on most everything.

MASTERSON: But for Burdick, a genetically engineered label wouldn't deter him.

BURDICK: I mean, I don't think there's much about genetically engineered food that scares me away, me and my children.

MASTERSON: So far, supporters of the labeling measure have raised $3.4 million. The amount is dwarfed by the nearly $25 million raised by the initiative's opposition. That includes Monsanto, Campbell's, and General Mills, who declined to comment for this story. Despite the cash disadvantage, recent surveys have the label it camp polling well ahead of the opposition. Still, they're bracing for a possible onslaught of anti-labeling ads between now and Election Day. For NPR News, I'm Kathleen Masterson in Sacramento. Transcript provided by NPR, Copyright NPR.