Organic tomatoes at a packaging plant run by the Del Cabo Cooperative in San Jose Del Cabo, Mexico, Dec. 27, 2011. Organic agriculture used to be synonymous with sustainability, but now with farms in the Mexican desert supplying tomatoes and basil to the American Northeast, that may not always be the case. (Marcus Yam/The New York Times) MARCUS YAM / NYT

Zucchini fields in Todos Santos, Mexico, where intensive farming for export is putting stress on the water table, Dec. 28, 2011. Organic agriculture used to be synonymous with sustainability, but now with farms in the Mexican desert supplying tomatoes and basil to the American Northeast, that may not always be the case. (Marcus Yam/The New York Times) MARCUS YAM / NYT