Wheat:  Net sales of 286,600 metric tons for 2019/2020 were down 53 percent from the previous week and 47 percent from the prior 4-week average.  Increases were primarily for Mexico (146,900 MT, including decreases of 2,800 MT), Colombia (57,400 MT, including 26,500 switched from unknown destinations), South Korea (53,600 MT), Ecuador (41,800 MT, including 24,000 switched from unknown destinations), and Chile (36,300 MT, including 33,000 MT switched from unknown destinations).   Reductions were primarily for unknown destinations (89,700 MT) and the Philippines (20,000 MT).  Exports of 509,300 MT were up 26 percent from the previous week, but down 1 percent from the prior 4-week average.    Corn:&nbsp...