The standard grades for apples when packed in barrels which shall be shipped or delivered for shipment in interstate or foreign commerce, or which shall be sold or offered for sale within the District of Columbia or the Territories of the United States shall be as follows: Apples of one variety, which are well-grown specimens, hand picked, of good color for the variety, normal shape, practically free from insect and fungous injury, bruises, and other defects, except such as are necessarily caused in the operation of packing, or apples of one variety which are not more than 10 per centum below the foregoing specifications shall be ''Standard grade minimum size two and one-half inches'', if the minimum size of the apples is two and one-half inches in transverse diameter; ''Standard grade minimum size two and one-fourth inches'', if the minimum size of the apples is two and one-fourth inches in transverse diameter; or ''Standard grade minimum size two inches'', if the minimum size of the apples is two inches in transverse diameter.