DES MOINES, Iowa — Donald Trump warned Saturday of a “war on the American farmer,” telling a crowd in Iowa that rival Hillary Clinton “wants to shut down family farms” and implement anti-agriculture policies. Trump’s speech at the annual “Roast and Ride” fundraiser for Republican Sen. Joni Ernst came just hours after Clinton received her first national security briefing as the Democratic presidential nominee. Trump skipped the 42-mile motorcycle ride that preceded the event in a state where polls show a tight contest, a rare bright spot for Trump amid a sea of challenging battleground states.