On Friday, U.S. President Donald Trump vowed to put a 'major tariff' on Mexico for lettuce he claims is behind the spread of a diarrhea-causing parasite and a 'big tariff' on Canada in response to wildfire smoke crossing the border. Shredded lettuce from a Mexican branch of American-based produce supplier Taylor Farms previously tested positive for Cyclospora at the U.S.-Mexico border. The FDA said it ended up being a false positive, but later clarified on social media there is still ‘overwhelm