DES MOINES, Iowa (AP) — The U.S. corn harvest continues ahead of schedule with some states nearly half-finished at a time when they usually are just getting started. The USDA said Tuesday in its weekly crop update that little has changed in the condition of drought-damaged corn and soybeans. That’s because the plants are too far along for recent rain to make a difference. Corn was planted several weeks earlier this year and matured more quickly in the summer heat, allowing farmers to start harvesting early. Tennessee has 49 percent of its corn in, compared to the usual 21 percent. Missouri is at 44 percent, ahead of the average 8 percent. Nebraska is at 7 percent, and Iowa, the nation’s leading corn producer, is at 5 percent. Typically those farmers haven’t begun yet.