11. No growing crop certificate may be issued containing a statement that seed potatoes are capable of being marketed as certified seed potatoes unless the authorised officer is satisfied that the immediately succeeding crop produced from the seed potatoes is likely to contain—
(a)in the case of—
(i)Union grade A, not more than 0.5%, and
(ii)Union grade B, not more than 0.5%,
by number of growing plants which do not breed true to variety or are a different variety; and
(b)in the case of—
(i)Union grade A, not more than 8%, and
(ii)Union grade B, not more than 10%,
by number of growing plants which show symptoms of severe virus diseases prevalent in Europe where those symptoms are attributable to infection in the mother crop.