|When we harvested our potatoes last year quite a few of them had spots that looked like they had been eaten out but looked like dirt. You could scrape it out. What caused it?|
|It's really difficult to diagnose a problem without actually seeing it but what you describe sounds like scab. Here's a publication with photos that you might find helpful: http://vegetablemdonline.ppath...
If it is scab, you'll also find recommendations for controlling the problem. Good luck with your potatoes!