Serious damage, unless otherwise specifically defined in this section, means any defect which seriously affects the appearance, or the edible or shipping quality of the celery stalk or the general appearance of the stalks in the container. Any one of the following defects, or any combination of defects the seriousness of which exceeds the maximum allowed for any one defect, shall be considered as serious damage:

Growth cracks when more than 4 branches are affected by growth cracks which are over one-half inch in length, or when more than 8 branches have growth cracks;

Horizontal cracks when more than 5 branches have horizontal cracks which are over one-half inch in length, or when more than 8 branches have horizontal cracks;

Pithy branches when more than 4 are pithy in that portion of the midrib between a point 11/2 inches above the point of attachment to the base and the first node, or between a point 11/2 inches below the first node and the point of attachment to the base, or when pith occurs at both ends of the midrib and more than a total of 11/2 inches is affected: Provided, That stalks having 6 outer branches or less shall have not more than one-half of the outer branches affected by pith as described above;

Seedstems when the length of seedstem exceeds 3 times the diameter of the stalk (see §§ 51.587 and 51.588);

Dirt when dirt is badly caked on the stalk;

Doubles when the inner branches are not fairly well protected;

Disease: (1) Brown stem, cracked stem and crater blotch when seriously affecting more than 4 branches, or when the aggregate area exceeds 1 square inch on the branches; and,

Discoloration when each of more than 5 branches or 1/2 of the branches of the stalk, whichever is less, has more than 3 distinct hair-like lines more than 3 inches long occurring on the outer side of the branch or an aggregate area of more than 1/4 by 1 inch of blotch or solid type discoloration occurring on the inner side;

Insects when worms are present, or when insect injury affects the midrib portion of more than 4 branches, or when injury on other portions seriously affects the appearance of the stalk; and,

Mechanical injury when the root has been cut off too closely leaving the branches without support; when more than 4 branches are materially scuffed or bruised; when the branches have been broken above the first node to an extent which seriously affects the appearance; or when more than 4 branches are broken below the first node except all branches may be cut below the first node provided the stalk is of the length specified.