WASHINGTON — Net export sales of U.S. corn in the week ended Dec. 26 tumbled 90% from a week earlier, 80% from the prior four-week average and fell well short of trade expectations. Part of the decline was the result of a 116,000-tonne cancellation of prior sales by China, and another 209,400-tonne cancellation by “unknown destination,” which often is seen by the trade as China.

Net export sales of U.S. corn for the week were 154,500 tonnes for delivery in the current 2013-14 marketing year and another 20,300 tonnes for delivery in 2014-15, the U.S.D.A. said. The combined total fell well short of trade expectations that ranged from 250,000 to 900,000 tonnes, which was a wider range than usual.

Earlier in December it was reported that China rejected 545,000 tonnes of U.S. corn shipments due to the discovery of an unapproved bioengineered strain of corn. Late in December China also rejected 2,000 tonnes of distillers’ dried grain for the same reason.

While the Christmas holiday may have had some impact on export sales last week, other grains and oilseeds fared far better than corn. Net sales of wheat totaled 256,500 tonnes for the two-year period, the U.S.D.A. said. Though down 58% from a week earlier for the current year, sales were within the 200,000 to 600,000 tonne range of trade expectations. Soybean sales for the week totaled 943,400 tonnes for 2013-14, up 31% from a week earlier, with sales of 237,500 tonnes also reported for 2014-15. The two-year total was well above the high end of trade expectations that ranged from 400,000 to 900,000 tonnes. China was the major soybean buyer.