Labor is and will likely continue to be a major issue for California farmers, according to a UC Davis agricultural economist. California agriculture employs a total of 800,000 to 900,000 workers annually, with the figure varying according to different times of the growing season, reports Philip Martin, a professor of agricultural and resource economics and an authority on farm labor issues. Most seasonal farm workers are immigrants who have entered the United States specifically for farm jobs. But because these workers don't intend to spend their careers on the farm, there will be a 10 percent turnover rate in the state's farm labor market, with 80,000 to 90,000 new immigrants entering the work force annually, predicts Martin. "There also could be significant union organizing activities in the next 10 years, since the AFL-CIO has placed a high priority on organizing immigrant workers, and the United Farm Workers union is moving aggressively to represent workers employed in canneries and packing operations, as well as on-farm workers," noted Martin. He adds that farm labor regulation and enforcement will continue to be controversial, but suggests that new U.S. and Mexican presidents, George W. Bush and Vincente Fox, may create a new agricultural guest worker program.