Tariff headlines and concern about the economy are expected to weigh on grains at the open. After a weak finish for many major markets last week, a recovery for grain futures may depend on whether stock prices can stabilize along with crude oil. In the Headlines The U.S. Trade Representative agency has proposed new port fees for ships built or flagged by China. Charges for Chinese vessels could range from $500,000 to $1.5 million per ship and would apply to what was recently estimated at about 17 percent of ships coming into U.S. ports that are Chinese-made. There were additional orders requiring an increase in the use of U.S.-built and U.S.-flagged ships, with American shipping companies growing to handle at least 15 percent of all exports over the next seven years. New tariffs and their risk of pushing inflation higher were part of what pulled stocks sharply lower on Friday. The latest reading on consumer sentiment also dropped 10 percent from last month, helping to lead the Dow Jones Industrial Average down for a loss of nearly 750 points. The risk-off move may have been exacerbated further by a massive amount of stock option contracts that expired at the end…