CBOT wheat futures slid, heading for a second straight losing session with pressure from record supplies from the Black Sea region making it difficult for U.S. exporters to win business. Soybeans dipped for a fourth consecutive session- although losses are marginal on expectation of a reduction in U.S. yields, while corn fell for the first time in three sessions as markets await key supply demand reports to be issued by USDA. U.S. wheat exports are responding to more competitive U.S. prices.