Technology is giving the food industry better tools for detecting problems in the food supply, such as e coli or salmonella contaminations. That’s partly why food recalls have increased in recent years. But quickly finding the source and final destination of unsafe food -- that’s a little more complicated. A recently enacted law requires the produce industry to come up with a system for tracking fruits and vegetables from field to fork, but as Harvest Public Media’s Abbie Fentress Swanson reports, there’s a big holdup.