“It’s like riding down the highway and expecting to keep the exhaust from your car within the boundaries of the road.”

ANDREW AND MELISSA DUNHAM spent years transforming their farm, which has been in his family for five generations, from a conventional producer of corn, soy, and alfalfa into a diversified operation with 40 different kinds of fruits and vegetables, a herd of 20 grass-fed cattle, even a few beehives. Finally, in May 2009, the couple’s 80 acres in Grinnell, Iowa – now named Grinnell Heritage Farm – became certified organic.

Just two months later, the Dunhams’ pickers spotted a crop duster flying low over nearby seed-corn fields, then noticed a cloud creeping toward them. The crew got out of the way as a fog of fungicide descended on two acres of hay, effectively revoking the acreage’s organic certification for three years, the chemical-free transition period required by the USDA.