(1) The department will not accept any field infested with nematodes.

(2) Detection of ring rot in a field will make that field ineligible for production of certified seed potatoes for three years. Presence of volunteer potato plants in a field with ring rot history will disqualify the current field crop for certification. Plants outside of the defined row are considered volunteers.

(3) Nuclear class seed potatoes must be produced in a field that has not been planted with potatoes for at least four years.

(4) Generation 1, 2, 3, 4, and 5 class seed potatoes must be produced in a field that has not been planted with potatoes during the previous year unless the prior potato crop was certified seed potatoes of an earlier class of the same variety. Volunteer plants from a previously planted seed potato crop will cause the class designation of the current crop to be changed to the appropriate generation of the volunteer plants.