California farm workers, many of them immigrants, are returning to their homes as they get older, causing a shortage of labor for farms. Due to stricter immigration enforcement, a better Mexican economy and a lack of interest in farm work, California farmers are having trouble finding low-skilled workers to harvest crops. About 70% of agricultural producers say that they are expecting a shortage of workers in the spring, and that they are unsure if they will have enough workers.
See "California farms face labor shortage as farmworkers age", The Associated Press, San Jose Mercury News, March 10, 2013