Farmworkers, union members and activists marched through city streets to Burger King headquarters Friday to protest low wages for tomato pickers and alleged exploitation of field workers.

About 300 to 400 protesters gathered under the skyscrapers of Miami's downtown, many wearing yellow T-shirts reading "Exploitation King" and "Burger King Exploits Farmworkers," others holding signs saying "Dignity" or "Justice for Tomato Pickers." The marchers, some strumming guitars and banging large tin cans with sticks, then began their nine-mile trek to Burger King's offices.

The protesters are pressuring the Miami-based fast-food giant to pay a penny more per pound of Florida tomatoes — with their suppliers passing the money on directly to farm workers.

Burger King has not accepted the penny-per-pound deal. The company, owned by Burger King Holdings Inc., says the door remains open for negotiation, but the mechanism of paying the extra penny directly to the workers "is very obscure and legally questionable." Tomato growers say it would be illegal to let outside groups set wages.

McDonald's Corp. and Taco Bell owner Yum Brands Inc. have reached similar agreements already with the Coalition of Immokalee Workers, who organized the march. But those deals are not currently in effect due to resistance from growers.

Pickers such as Sonia Lopez, 50, want better work conditions and higher wages. Many Immokalee tomato pickers must toil in the dirt and hot sun for modest wages, living in cramped trailers with no overtime or health care. Most field workers are immigrants, and are here illegally.

"We want just a penny per pound, that's not a lot," Lopez, 50. "It will help our quality of life. It will help people make more money and be able to live a decent life, a better life. This affects all of us."

Nearby, Juan Antillon, 48, also a farm worker in Immokalee, holds a protest sign with tough, hardened hands weathered from picking tomatoes for seven years.

"It's going to be a difficult march, but one that I'll finish," Antillon said. "This is a small step but an important one."

Florida supplies 80 percent of America's domestic fresh tomatoes between Thanksgiving and February. The agreements reached with McDonald's and Yum Brands were mostly symbolic, affecting only a tiny segment of Florida tomato pickers, but they paved the way for raising wages and strengthening farm worker rights across the industry.

Worker wages would essentially double if the McDonald's and Yum Brands deals are adopted industrywide. Yum Brands says it is still committed to the coalition, yet after two successful seasons, its suppliers opted out this year. McDonald's has yet to find any supplier who will participate but will continue to buy Florida tomatoes either way.

Steven Grover, a Burger King vice president in charge of food safety and quality assurance, said the door remains open for negotiation, but the mechanism of paying the extra penny directly to the workers "is very obscure and legally questionable from a number of angles."

Grover said the protest was the coalition's way of stirring up controversy.

"This protest is a colossal waste of resources and time that could be focused on helping the migrant workers in Immokalee," he said.

Tomato farm workers were not the only ones marching Friday. They were joined by members of area unions, religious leaders and even high school students from Naples.

Oscar Salas, a former orange picker from Tampa area who works as a construction worker, said he's seen instances where employers threatened to call immigration authorities if workers asked for more money.

"Wages (for orange pickers) have been stagnant out there for 30 years, just like tomatoes," said Salas, 30, of Dade City. "I realized that my housing conditions were affected by the low wages my family lived and worked under for 20 years. We're not even middle class."