CHICAGO — CME Group on Nov. 11 announced plans to implement variable storage rates for the C.B.O.T. wheat futures contract, beginning with the July 2010 contract. CME said it has filed an amendment with the Commodity Futures Trading Commission to its original request sent this fall to begin variable storage rates with the September 2010 contract. CME said it has been working closely with the C.F.T.C. and the commission’s committee on convergence adding that the change to the July contract from the September "is agreeable to our customers" and would not materially change implementation. The National Grain and Feed Association had advocated a more aggressive timeline, beginning with the December 2009 contract. CME said terms of the program also have been changed slightly with the trigger for a rate increase eased to 80% of financial full carry from 85% under the previous plan. Under the variable storage rate concept, storage charges assessed by grain elevators approved for delivery against wheat future contracts would expand or contract based on the carrying charges in the market implied by futures markets spreads. The change has been proposed in an effort to improve convergence between cash markets and futures at futures contract expiration.