Verticillium wilt............................................................ Fusarium wilt ................................................................ Wildings........................................................................ Cultivar mixtures .......................................................... Off-types ....................................................................... Mild mosaic .................................................................. Bolters ........................................................................... 2 2 2 1 1 1 1 Virus post control 6. Samples for virus post control shall be taken in the field after haulm destruction. A minimum of one thousand tubers per field shall be sampled. 7. The determination of virus shall be done by serological methods and/or by occular inspection. The result shall be given as a percentage by number of infected tubers. Tuber control 8. From each lot presented for tuber control at least five primary samples of a minimum of forty tubers each shall be drawn. The primary samples mixed together shall form the working sample to be examined. At least 500 tubers per seed lot shall be examined. 9. The working samples shall be washed, and all the tubers shall be cut through before they are examined. 10. Diseased, damaged and severely mis-shaped tubers and tubers deviating in size from the grade size shall be recorded as percentage by number; and the percentages found shall be multiplied by the appropriate factors as set out in note 11 and the various products so obtained shall be added together to give the defect index for the seed lot. 11. The factors to obtain the defect index for the tuber control of a potato seed lot are as follows: Defect Pink rot.......................................................................... Pythium rot.................................................................... Soft rot .......................................................................... Spindle tuber ................................................................. Black leg ....................................................................... Fusarium ....................................................................... Phytophtora ................................................................... Other dry rots ................................................................ Root knot nematodes..................................................... Alternaria ...................................................................... Black heart .................................................................... Black scurf .................................................................... Sunscald ........................................................................ Tuber moth.................................................................... Cut worms..................................................................... Factor 10 10 10 10 3 3 3 3 3 1 1 1 1 1 0.50