CANADA UPHOLDS COUNTERVAIL DUTY ON U.S. CORN The Canadian Import Tribunal ruled today subsidized U.S. corn imports were injurious to Canadian growers and upheld a countervailing duty of 84.9 U.S. cts a bushel set earlier this year. The ruling is the result of trade action launched in 1985 by the Ontario Corn Producers Association that contended U.S. subsidies were driving American corn prices below Canadian production costs. A spokesman for the Department of Revenue said a study of the level of the duty will be undertaken in the next six months to determine if it should be adjusted.