News Snapshot:
(Corrects second paragraph to remove reference to Brazil's harvest, and assigns it to soybeans in fourth paragraph) * Wheat futures hit 20-month low * Black Sea corridor and U.S, Europe rain ease supply worries * Another flash sale of U.S. corn to China By Cassandra Garrison MEXICO CITY, March 22 (Reuters) - Chicago grains futures fell on Wednesday, with wheat hitting a 20-month low, on the continuation of a wartime Black Sea export deal and with markets cautious ahead of the Federal Reserve's policy decision. The most-active wheat contract on the Chicago Board of Trade (CBOT) fell 2.23% to $6.68-1/4...
