Serious damage means any injury or defect which seriously affects the appearance, or edible or shipping quality. 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:

Crater rot, when moist, or when occurring on more than three branches, or when aggregating more than one square inch on the branch or branches.

Cutworms, when the worms are present, or when worm injury occurs on the heart branches, or when occurring on the midrib portion of more than three branches, or when aggregating more than one square inch on the midrib portion of the branch or branches.

Growth cracks, when the stalk has more than two branches affected by growth cracks any of which are more than one-half inch long.

Pithy branches, when the midribs of more than two branches are pithy. Pithy branches means those which have a distinctly open texture with air spaces in the central portion.

Seedstems, when the stalk has a seedstem the length of which is more than three times the greatest diameter of the stalk. The greatest diameter of the stalk shall be measured at a point two inches above the point of attachment of the outer branches to the root. The length of the seedstem shall be measured from the point of attachment of the outer branches at the base of the seedstem to the top of the actual seedstem, exclusive of any leaves or leafstems attached to the top of the seedstem.

Rust, when there are more than fifteen hair-like lines of any length on one or more heart branches, or when there are more than one and one-half square inches in the aggregate on branches other than heart branches.

Cracked stem, when there is more than one square inch in the aggregate on any or all branches.