(1) A grower may not recertify any seed lots, except nuclear, if ring rot has been detected on his or her seed potato farm during the previous two years. Nuclear seed potatoes may be recertified by the original grower if laboratory testing of the seed by a laboratory approved by the department shows negative results for ring rot.

(2) Prenuclear class.

(a) Prenuclear seed lots must be derived from disease tested micropropagated plants. All testing methods and laboratories must be approved by the department.

(b) A minimum of one percent (and not less than twenty samples) of prenuclear seed produced in a greenhouse must be tested and found free of potato virus X (PVX), potato virus Y (PVY), potato virus S (PVS), potato leafroll virus (PLRV), Erwinia carotovora ssp. caratovora (soft rot), Erwinia carotovora ssp. atroseptica (black leg), and Clavibacter michiganense ssp. sepedonicus (ring rot).

(c) The department will inspect all facilities used in the production of prenuclear class seed potatoes on a periodic basis. Department approval is necessary in order to utilize these facilities.

(3) Nuclear class.

(a) Nuclear class seed potatoes must be propagated entirely from prenuclear plants.

(b) Each nuclear class seed lot must be distinctly separated in storage and in the field.

(c) If a ground rig is used for spraying, wide enough spacing between rows must be left, so that tires will not touch plants during the growing season.

(d) Growers must plant cut seed and single drop seed separately, with single drop seed identified.

(4) Generations 1, 2, 3, 4 and 5.

(a) Growers must leave a distinct separation between lots of seed potatoes from different classes. The same separation must be left between different varieties, unless the varieties are readily distinguishable by visual observation. The separation must consist of one of the following:

(i) A strip of land at least six feet in width, that is unplanted or planted with another crop; or

(ii) Visible markers such as flags in every corner of the lot, and also at intervals not to exceed one hundred yards.

(b) When more than one lot of seed potatoes is planted in the same field, growers must stake or mark the identity of each lot.

PDFWAC 16-324-385

Production requirements.