This section is from the book "The Potato: A Compilation of Information from Every Available Source", by Eugene H. Grubb, W. S. Guilford. Also available from Amazon: The Potato: A Compilation Of Information From Every Available Source.
The home-made box is usually less satisfactory. It is rarely made of the best light material, and when one takes into account the number of times the boxes must be handled, he may see the advantage of having the very best. Manufacturers furnish solid boxes that weigh only seven pounds, are exact in size, trim in appearance, and will last for fifteen or twenty years, if cared for properly. Other boxes, slatted on ends and sides, are furnished at a less price, and are less substantial. The boxes, bought in crates of a dozen, cost about 18 cents apiece for the solid ones and 14 cents for the slatted.
The potatoes are picked up after the digger and placed in the boxes, the unmerchantable tubers being left on the ground. When a load is ready, the boxes are handed up to the driver of the wagon, and while he takes the load to the car, cellar or other place of storage another load is made ready by the pickers. Returning, the driver puts his empty boxes out, takes on his load of full ones, and the work proceeds with a minimum amount of handling. If the potatoes are drawn directly to consumers, neat boxes for handling them are a good advertisement as well as a means of saving labor, time, and injury to the stock.
When good seed, cut to two eyes, has been planted in good ground, and the tillage has been right, the number of unmarketable potatoes usually is small, and many years we do not pick them up. It is the practice of some growers to pick up all sizes together and then to sort out those that are not merchantable, using the best of these for planting and the remainder for stock feed. The small tubers are not the most desirable for use as seed. If there is a considerable proportion of the crop that is too small for market it should be gathered from the ground after the merchantable potatoes have been taken up."
The practice of washing potatoes is not common, and there is a general idea that it is detrimental, but the Wisconsin Farmer says editorially:
A good deal may be said in favor of the practice of washing potatoes, provided they are thoroughly ripened before being dug. We know of one instance where a shipper of early potatoes refused to fulfil his part of the contract on account of a customer having washed his early potatoes. He said that washing greatly impaired the keeping quality of early varieties. However, in the case of mature potatoes, if for any reason they are dug at a time when the dirt adheres to them, it will undoubtedly pay to give them a good washing. Nevertheless, it is highly important that they be thoroughly sun-dried before they are stored in the cellar or cave or before they are placed in sacks. It is reasonable to suppose that dried mud adhering to potatoes will carry a certain amount of germ life, and it is not strange if some of this form of life tends to induce decay. One grower informs us that he makes a practice of thoroughly washing his potatoes every year, after which they are stored in bushel boxes. The claim is made that by this method the highest , market price is obtained on account of the fine, clean appearance of the tubers, and also on account of the splendid condition in which they keep stored in this fashion."
An Iowa grower believes in the practice of washing potatoes, and says in the Wisconsin Farmer:
According to my experience, too much cannot be said in favor of throughly cleaning potatoes as soon as they are dug. The finest crop I ever saw was rotting in the ground on account of the weather being hot and moist. As soon as they were dug the spray-pump was started and the potatoes thoroughly washed. They were then allowed to dry before being housed, and after being sorted not a solitary tuber decayed. I had another experience that tends to corroborate this practice. Over a year ago I bought some potatoes, but when they were delivered they were covered with dry mud. These potatoes when cooked had a nauseating taste, and in several instances had a sick ening effect. I came to the conclusion that when potatoes were left in this dirty condition germs of disease were present, and it is my opinion that the law should prohibit the marketing of potatoes in this condition. Not only are they unwholesome, but they are much more apt to decay than if they are thoroughly cleaned by washing."
Another grower condemns the washing of the tubers and says:
All any one need do to know whether it spoils them or not is just to try it. Cook some that have been washed a week or two; then cook some that have been dug when the ground was in condition - the more fresh dirt among them the better - and see how much better and more mealy and palatable they are than the washed ones. Potatoes that are to be kept over winter should be left in the ground as long as possible, until there is danger of freezing them. Then dig when the ground is in condition, not when the mud will stick to them, and the more fresh dirt the more brittle and fresh they will come out in the spring."
The natural, normal way to take potatoes from the ground and store them is when the soil is dry. When this is the case no washing is necessary.
Whether harm comes with washing depends on the drying and after care, and the need of washing depends on the amount of mud adhering to the tubers when they are dug.
Good, hard headed, common sense is required in all harvesting operations, and no rules can cover all conditions.