Student Nicholas Klayman washes swiss chard to be sold at the farmers market as part of the horticultural program at the Perkins School for the Blind in Watertown, Massachusetts, U.S., July 27, 2017. REUTERS/Brian Snyder 

Swiss chards is seen at the fruits and vegetables pavilion in Rungis International food market as buyers prepare for the Christmas holiday season in Rungis, south of Paris, December 11, 2015. REUTERS/Philippe Wojazer 

Swiss chard is seen at Rungis International food market as buyers prepare for the holiday season in Rungis, south of Paris, December 11, 2014. The holidays are a busy time at Rungis, the largest fresh food market the world, where wholesalers selling everything from oysters and salmon to gruyere, green beans and sides of beef is abuzz the week before Christmas. Located 7 kilometres south of Paris, Rungis is spread over 234 hectares and employs some 12,000 workers. Rungis had sales of 9 billion euros ($11.22 billion) in 2013, up 3.8 percent from 2012. Picture taken December 11, 2014. REUTERS/Philippe Wojazer (FRANCE - Tags: FOOD BUSINESS) 

Swiss chard is seen at Rungis International food market as buyers prepare for the holiday season in Rungis, south of Paris, December 11, 2014. The holidays are a busy time at Rungis, the largest fresh food market the world, where wholesalers selling everything from oysters and salmon to gruyere, green beans and sides of beef is abuzz the week before Christmas. Located 7 kilometres south of Paris, Rungis is spread over 234 hectares and employs some 12,000 workers. Rungis had sales of 9 billion euros ($11.22 billion) in 2013, up 3.8 percent from 2012. Picture taken December 11, 2014. REUTERS/Philippe Wojazer (FRANCE - Tags: FOOD BUSINESS) 

A man sows Swiss chard in an urban garden in Havana August 11, 2009. Cuba's urban agriculture movement, developed in the 1990s as a response to the food crisis after the collapse of its former benefactor the Soviet Union, provides over 50 percent of the vegetables Cubans eat. REUTERS/Stringer (CUBA AGRICULTURE) 

Farmer's Market intern Marianna Bellou harvests swiss chard on an urban farm plot in the Dorchester neighborhood of Boston, Massachusetts August 9, 2007. Each year The Food Project hires 60 youth to grow food on their farms in Boston and Lincoln, Massachusetts, during which these teens harvest and distribute over 60,000 pounds of produce at a farmer's market in Dorchester and to hunger relief agencies in greater Boston. REUTERS/Brian Snyder (UNITED STATES)