Choosy moms will have little choice but to pay more for peanut butter.

Another hot, dry summer has devastated this year's peanut crop, sending prices for the legume skyrocketing and forcing peanut-butter brands including J.M. Smucker Co.'s Jif, Unilever NV's Skippy and ConAgra Foods Inc.'s Peter Pan into startling price increases.

Wholesale...