DeWITT — President Donald Trump’s go-it-alone approach on trade with China put a bull’s-eye on American farmers, former U.S. Secretary of Agriculture Tom Vilsack said Tuesday.Had the White House enlisted allies like Europe and Japan, then China would not have been able to retaliate the way it has, he said.“When was the last time the United States of America went to war without an ally,” Vilsack asked.