CBOT corn futures dropped to contract lows for the fourth straight session amid technical selling, abundant global grain supplies and good U.S. crop conditions. U.S. cash corn markets continued to weaken as farmers sold supplies remaining from last year ahead of the harvest of the new crop, which was expected to begin in the Midwest region in the next several weeks. Traders are liquidating positions in front-month CBOT September corn ahead of first notice day for deliveries against the contract on Thursday. The September-December corn spread also hit a lifetime low.