U.S. wholesale prices fell in March, with energy prices recording their biggest fall in three years, U.S. Labor Department reported on Friday. The Producer Price Index (PPI), which measures price changes at the factory gate, dipped 0.6 percent last month on a seasonally adjusted basis. It was the biggest drop since May last year and followed a 0.7 percent gain in February. Energy prices went down 3.4 percent last month, the largest monthly decline since February 2010. They were mainly dragged down by a slump of 6.8 percent in the gas price. Meanwhile, food costs rose 0.8 percent last month after falling 0.5 percent in February. Excluding the volatile food and energy sectors, the so-called \"core\" wholesale prices edged up 0.2 percent last month from February, which indicated general inflation pressure is still under control. Wholesale prices rose 1.1 percent over the 12 months ending March.