US producer prices last month registered the biggest drop since September, pulled down by tumbling energy, clothing and food prices.

The Labor Department said Friday that its producer price index, which measures cost pressures before they reach the consumer, slid 0.4 percent in July. It was the first decline since March and biggest drop since a 0.5 percent fall last September. Over the past year, producer prices are down 0.2 percent.

Energy prices fell 1 percent and food prices 1.1 percent in July from June. Corn prices plummeted 22.2 percent, biggest drop since September 1996. Producer prices of clothing, jewelry, shoes and accessories dropped a record 6 percent.

Excluding the volatile food and energy categories, core producer prices dropped 0.3 percent, biggest decline since February 2015. Since July 2015, core producer prices are up 0.7 percent.

Inflation remains modest at both producer and consumer levels. Consumer prices rose a modest 0.2 percent in June and were up just 1 percent from a year earlier, well below the Federal Reserve's 2 percent annual target. The Fed left interest rates unchanged at its meeting last month but noted that risks to the U.S. economic outlook have diminished, opening the possibility of rate hikes later in the year.

The American economy grew at a disappointing 1.2 percent annual rate from April through June. But the U.S. job market looks strong. Employers added 255,000 jobs last month, and the unemployment rate is 4.9 percent.