TUBER QUALITY STANDARDS

All seed potato classes are subject to the same tuber standards--there is only one quality grade for Canada Seed Potatoes. The total allowable disease and defects permitted in a graded seed potato lot are set out in section 48.1, subsections (2) - (10) of the Seeds Regulations. The following is a summary of the shipping point tolerances:

Disease or Defect	Tolerence Level (%)
Soft rot or wet breakdowns	0.1
Dry Rot	1
Scab or Rhizoctonia - light	10
Scab or Rhizoctonia - moderate	5
Stem-end discolouration due to top-killing, frost, heat, or drought with penetration from 6 - 13 mm	4
Tubers malformed or externally damaged	2
Total number of tubers affected by disease and defects, not including slight scab and rhizoctonia and stem-end discolouration	5

Soft rot or wet breakdownsv
In addition there should be no more than the following levels of foreign varieties: not more then 0.05% in Elite III, not more than 0.10% in Elite IV, and not more than 0.20% in the Foundation and 0.50% in the Certified classes of seed.