Florida's largest tomato grower [Six L's] has joined the Coalition of Immokalee Workers' Campaign for Fair Food, pledging to improve working conditions in their fields and pass on a penny-per-pound raise...The pact calls for a cooperative complaint resolution system, a participatory health and safety program, and a worker-to-worker education process...Pacific Tomato Growers, another industry giant, signed the accord last week…Six L's and Pacific were tainted by a 2008 federal slavery case, in which members of Immokalee's Navarrete family went to federal prison for enslaving 12 workers...brought to work in both growers' fields...the coalition developed a work-around strategy: If growers wouldn't come to the table, they'd go directly to the growers' customers...the coalition forged agreements with the world's major fast-food companies, institutional food services and others, including McDonald's, Burger King, Whole Foods and Sodexo...[includes statement by Six L's]