Pre-basic seed potatoes
6. A growing crop certificate must not be issued containing a statement that seed potatoes are capable of being marketed as pre-basic seed potatoes of pre-basic 1, pre-basic 2, pre-basic 3 or pre-basic 4 class unless, in the opinion of the authorised officer, the immediately succeeding crop produced from the seed potatoes is not likely to contain—
(a)more than 0.01 per cent by number of growing plants which deviate from variety and type; or
(b)more than 0.01 per cent by number of growing plants which show symptoms of either mild or severe virus diseases where those symptoms are attributable to infection in the mother crop.