Retaliation Against Mexico The Mexican government is imposing a 50 percent tariff on white corn imports to protect its growers from competition. This is a much more surgical approach than its proposed ban on all GM corn imports. Only 4.5 percent of U.S. corn exports to Mexico is white corn but the tariff will still violate the USMCA.  It will require some kind of response from Washington but what? Over the past decade the U.S. has exported an average 840 KMT of white corn per year to Mexico. That has a value of around $220 million based on an average 13.3 percent price premium over U.S. yellow corn.  Mexico’s policy will no doubt hurt Mexican consumers dependent on white corn-based tortillas for a significant share of thei...