On the last Monday of September, 32 field workers stepped onto a 15-acre experimental plot in an undisclosed part of Washington and made apple harvest history. The fruits they plucked from each tree were only a few months old. But they were two decades and millions of dollars in the making. And when they landed, pre-sliced and bagged on grocery store shelves earlier this month, they became the first genetically modified apple to go on sale in the United States.