China’s purchases of U.S. corn have slowed significantly due to worries the grain might be drawn into the trade spat between the world’s two largest economies, and as Chinese customs keeps the brakes on clearances for cargoes. Chinese buyers have canceled multiple cargoes of corn so far this year, the latest product roiled by the China-U.S. trade tensions. Now some traders say they have halted buying from the United States completely despite signs some of the trade tensions may be starting to ease. Some Chinese corn buyers switched to rival supplier Ukraine earlier this year, as Beijing tightened controls on processing genetically modified strains of the crop. Corn from the United States is mostly genetically modified.