One would think a simple google search would get you the answer in about 30 seconds. I'm not going to do the work for her, she's obviously too lazy, or perhaps simply stupid and hadn't thought of google.
The other side of me want's to help her though so here it goes. Big Mo, this is for you...
Go to a lawn care specialist and get some Atrazine, the recommended rate is about a pound per acre, it's pretty weak though so I suggest 5 pounds per acre. Apply before the ground freezes or first thing in the spring. It will neutralize any residual potato bacteria making the ground safe for replanting potatoes again the following year. Really.