(1) The official blue tag shall be used to designate seed lots that are the equivalent of the U.S. No. 1 grade with the following exceptions:

(a) size -- the minimum size shall be 1 1/2 ounces and the maximum size shall be 12 ounces.

(b) combined total length of growth cracks may extend two-thirds length of tuber and/or the depth of one-fourth the diameter of the tuber.

(c) cuts and bruises shall be scored when removal causes loss of more than 10% of the total weight of a tuber.

(d) air cracks shall be scored only if the depth exceeds 1/2 inch.

(e) sunburn (greening), hollow heart, hollow heart with discoloration, light brown discoloration or brown center shall be permissible.

(f) stem-end discoloration -- serious discoloration extending beyond a depth of 1/2 inch shall be scored unless verified by a department approved pathologist as not being a disease symptom.

(g) immaturity, as indicated by feathering of skin, shall not disqualify provided there is no undue loss of weight from wilting or shriveling of tubers.

(h) sprouts - - not more than 10% of the lot may have sprouts more than 3/4 inch in length. Individual sprouts or clusters shall not be scored on appearance or length if within the 10% tolerance.

(i) oversized, undersized, and sprouts shall be permissible provided the excess tolerance is indicated on the official grade certificate.

(j) freezing injury other than the condition of being frozen or affected by soft rot or wet breakdown shall be scored when removal of the affected area causes a loss of more than 10% of the total weight of the tuber. The tolerance is 3% or less for freezing injury.

(k) the tolerance is 1% or less for potatoes which are affected by late blight tuber rot, soft rot or wet breakdown.