Prices are set to spike following one of the worst peanut harvest seasons growers have seen in years.

Prices for a ton of runner peanuts, commonly used to make peanut butter, hit nearly $1,200 this week, according to the U.S. Department of Agriculture. That’s up from just $450 per ton a year ago.

It won’t be long before consumers see this price increase reflected on store shelves.

Kraft will raise prices for its Planters brand peanut butter by 40% starting Oct. 31, while ConAgra expects increases of more than 20% for its Peter Pan brand.

A spokesperson for Unilever, which makes Skippy, would say only that it’s watching the situation “very closely.”

Representatives for J.M. Smucker, which makes Jif, did not respond to a request for comment, though the Associated Press reported that Jif’s wholesale prices are set to rise 30% in November.

What’s to blame for this sticky situation? The intense heat and drought that hit the southern U.S. this year, said John Beasley, a professor of crop physiology and management at the University of Georgia.

“It was just unmerciful, and we had a lot of problems setting the crop,” he said. “I literally walked some fields that had zero yield.”

http://money.cnn.com/2011/10/14/markets/peanut_butter_prices/index.htm?hpt=hp_t2