Wheat headed for the worst run of quarterly losses in 14 years as bumper harvests in parts of the Northern Hemisphere offset ongoing tension in the Black Sea after the collapse of a grain agreement. Futures in Chicago have lost around 11% over the past three months and are poised for a fourth quarterly decline. While Moscow exited a safe-passage deal in July that allowed Ukraine to export its grain, plentiful supplies have kept a lid on prices. Russia was one of the countries to record a bumper harvest.