Wholesale food prices rose last month by the most in 36 years, and experts can't say how high they'll ultimately go. As the effects appear everywhere from the supermarket to fast food restaurants, an economist in Penn State's College of Agricultural Sciences said farmers probably won't be reaping much of the increase.

James Dunn, professor of agricultural economics, said prices for corn, wheat, soybeans and just about all large-production crops are higher than they were one year ago. He points to a long-term increase in global demand as the most salient of several factors.

"We had a big spike in commodity prices in 2007-2008, when there was a good worldwide economy and the prices of everything went high that year, too," he said. "Then the global recession hit. As we come out of it, we're seeing increasing demand resume. Then last season's bad weather in northern Europe, Poland and Russia really hit the feed-grain markets."

The United States typically exports grain to cover worldwide shortfalls, but U.S. production also faltered last year. Demand for soybeans outstripped supply despite a record crop, and there was record demand for wheat. It all results, Dunn said, in a perfect storm for high commodity prices.

"Last year was a particular challenge, and we're going into this growing season with a very small crop inventory," he said. "Ethanol production now consumes nearly 40 percent of the nation's corn crop, up from about 10 percent a decade ago, and there's growing demand for meat and dairy products in places like India and China.

"The combination of more people, low agricultural production and weather snafus means we'll have pretty high commodity prices for the next year or so."

Dunn cautioned that the current high food prices originate at the farm level, but few people buy food at the farm level. Most of the modern American food dollar goes to processing, transportation and marketing and not to the producers. So, rising farm prices won't hit all foods equally.