I'm going to get involved in this question for training (myself) purposes.
My question would be, is the farm a Partnership, Corporation, LLC or is it just Mr. and Mrs. Farmer? If Mrs. Farmer is a partner, member or officer, my understanding is that having a completed and signed Borrowing Resolution/Authorization in file would aleviate your current fear. As in the recent Compliance Action article, "Checking Applicants and Signatures"
If they are just individuals I punt and refer to our esteemed colleagues for help.