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Potatoes are divided into U.S. No. 1, U.S. Commercial, and U.S. No. 2 grades (though there are separate categories for processed and seed potatoes).

Generally speaking, the percentage of defects shown on a timely government inspection certificate should not exceed the percentage of allowable defects, provided: (1) transportation conditions were normal; (2) the USDA or CFIA inspection was timely; and (3) the entire lot was inspected.

U.S. Grade Standards Days Since Shipment % of Defects Allowed Optimum Transit Temp. (°F)
8-[5 int, 5 ext]-1 5
14-[10 int, 10 ext]-3
13-[10 int, 10 ext]-3
12-[9 int, 9 ext]-3
11-[8 int, 8 ext]-2
10-[7 int, 10 ext]-2
50-60° (early)
40-50° (late)

Canadian good arrival guidelines (unless otherwise noted) are broken down into five parts as follows: maximum percentage of defects, maximum percentage of permanent defects, maximum percentage for any single permanent defect, maximum percentage for any single condition defect, and maximum for decay. Canadian destination guidelines are 15-15*-5-10-3 (the 15% permanent defects allows for no more than 3% hollow heart, 5% undersized, and 5% oversized potatoes).

References: DRC, PACA, USDA.


• At destination, not more than 5% of potatoes may have sprouts longer than a half-inch in length, or clusters materially affecting the appearance
• Silver scurf is scored as a defect, as damage, when more than 50% of the surface is affected
• Internal black spot, normally found affecting the shoulders and stem end, is scored as a defect when affecting more than 5% of the total weight of the potato
• Size ‘A’ potatoes must meet a minimum diameter of 1.875 inches and at least 40% must be 2.5 inches in diameter or 6 ounces in weight or larger.

Source: Tom Yawman, International Produce Training,

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This information is for your personal, noncommercial use only.