Wholesale prices plunged last month, reflecting big downturns in the cost of food and energy. Stripping out those, core inflation was slightly stronger than expected. The producer price index declined 1.4% in February, reversing a rise of 0.3% the month before and falling much faster than the 0.2% decline that economists had predicted. Core inflation, however, rose 0.3% last month, one-tenth of one percentage point more than forecast. The slide in the headline number was the largest in three years and reflected a 4.7% plunge in energy prices and a 2.7% decline in food prices. A big decrease in the market price for natural gas accounted for much of the decrease in energy costs. The rise in the core number reflected higher prices for both commodities and the equipment used to produce them, as well as rising truck, plane and construction-equipment costs. Tuesday's number offers yet another conundrum for traders trying to stay ahead of the Federal Reserve. In the past, core inflation has resisted gains in the headline number, a trend that has appeased would-be hawks on the Federal Open Market Committee. Bond yields held steady at about 4.67% on the 10-year note following the print, while stock futures remained moderately lower. Last week, the Labor Department said its consumer price index rose 0.1% in February on both the headline and core number. Economists had been expecting readings of up 0.1% on the headline number and up 0.2% on the core.