Recent breakdowns in the system meant to keep experimental genetically engineered plants from contaminating the hundreds of millions of acres of crops grown in the U.S. has farmers and import markets questioning the purity of U.S. goods.

Mexico, the largest foreign market for U.S. rice, sent tremors through the U.S. sector last week when it stopped shipments on the border out of concern the U.S. cannot keep its experimental transgenic long-grain rice out of commercial crops.

California's medium-grain rice growers have demanded a statewide moratorium on any biotech field trials to avoid the contamination recently plaguing long-grain growers in the South.