[blackberryjam]

I have potatoes coming up from last year, should I dig them up. I'm not sure whether they're be ok to eat.

[arugula]

These volunteers will compete with other crops if left in the ground, so it's best to dig them up and dispose of carefully. I'd wait and eat this year's.

[mumofstig]

A recent thread discussed this and the blight risk 
You'll find it here
http://chat.allotment-garden.org/index.php?topic=105770.msg1186354#msg1186354

[fatcat1955]

They can also carry over diesease from last year. Dig them up.

[blackberryjam]

Thanks for the advice , we will dig them up ASAP, the volunteer spuds are from the previous owner and they must be deep down  because hubby dug the bed over about three times.
Fortunately there not near where we have planted our first years crop, and I have not sown anything in that part of the bed yet.