Wheat:  Net sales of 339,000 metric tons for 2018/2019 were down 22 percent from the previous week and 30 percent from the prior 4-week average.    Corn:    Net sales of 1,006,700 MT for 2018/2019 were reported for Mexico (354,600 MT, including 63,000 MT switched from unknown destinations and decreases of 22,200 MT), Japan (281,700 MT, including 35,400 MT switched from unknown destinations and decreases of 274,900 MT), South Korea (195,600 MT, including 186,000 MT switched from unknown destinations), Taiwan (166,900 MT, including decreases of 65,200 MT), and Colombia (108,700 MT, including 67,000 MT switched from unknown destinations).  Reductions were reported for unknown destinations (267,100 MT) and th...