A long strip of deep and fertile soil pinched by sharply rising mountains, the valley has more than doubled its output of produce in recent decades and now grows well over half of America’s leaf lettuce. Yet one place the valley’s bounty of antioxidants does not often appear is on the tables of the migrant workers who harvest it.

Public health officials here describe a crisis of poverty and malnutrition among the tens of thousands of farmworkers and their families who tend to the fields of lettuce, broccoli, celery, cauliflower and spinach, among many other crops, in an area called the salad bowl of the nation.

More than a third of the children in the Salinas City Elementary School District are homeless; overall diabetes rates are rising and projected to soar; and 85 percent of farmworkers in the valley are overweight or obese, partly because unhealthy food is less costly, said Marc B Schenker, a professor at the University of California, Davis, who studies the health of farmworkers.

“The people who grow our food can’t afford to eat it, and they are sicker because of it,” said Joel Diringer, a public health specialist and advocate for farmworkers. “It’s an incredible irony that those who work in the fields all day long don’t have access to the fresh produce that they harvest.”