Today, U.S. crop production includes about 86 million acres of field corn, 75 million acres of soybeans, 55 million acres of wheat, 21 million acres of alfalfa, and 9-plus million acres of cotton. These gargantuan numbers dwarf specialty crop acreage  which includes 151,000 acres of head lettuce and 37,000 acres each of spinach and cauliflower. Today, 60-plus herbicides are registered for weed control in field corn and soybeans. More than 20 herbicides help prevent weeds in cotton. Fewer than 10 herbicides  are registered for cole crops, lettuce, melons, and spinach.
Source URL: http://www.westernfarmpress.com/vegetables/long-wait-specialty-crop-herbicides