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.
While 'drawing' the sets it is a good plan to have at hand a large pail or a tub containing water to which there has been added a quantity of clay and cow manure which has been stirred until it forms a thin slime. As the plants are pulled from the bed they are taken in small bunches and their roots dipped into this mixture. This process, termed ' puddling,' covers the roots with a coating which not only prevents their becoming dry in handling but insures a direct contact with the soil when they are planted in the field or garden.
The success of the crop depends largely upon the way in which the plants start after being removed from the bed and set in the field or garden. Practical growers always plan to set the plants during a ' season' or period when the conditions are suitable to a quick start into growth, either just before a rain or as soon afterward as the soil can be worked. The method of setting will depend entirely upon local conditions and the acreage to be grown, the essential features, however, being to get the roots in contact with moist earth and the soil firmly pressed about the plants.
The use of water around the roots of the plants is desirable under most circumstances, as it not only moistens the soil but assists in settling it about the roots. A large quantity of water is not necessary, one half pint to each plant being generally considered sufficient.
Where level culture is practised, the plants are set from 24 to 30 inches apart in each direction. On the eastern shore of Virginia the greater portion of the crop is planted 24 inches apart each way, requiring about 11,000 plants to an acre. By planting 30 inches apart each way, only about 7,000 plants are required to set one acre. Where the crop is grown on ridges it is customary to have the ridges from 36 to 42 inches apart from centre to centre and to place the plants 14 to 18 inches apart in the row. By this method an acre will require from 8,000 to 12,500 plants. An acre of good sweet potato land will readily support 9,000 to 11,000 plants, and the number most commonly planted by the several methods will fall within these figures.
The machine transplanters are provided with a spacing device which indicates the distance between plants; also with a row marker to show the location of the next row.
Where a few hundred plants are to be grown for home use, or if only an acre or two are to be planted, the hand method of planting will answer every requirement. A trowel or a dibble is used for opening the soil to receive the plant, and the earth is closed about the roots by a second thrust with the implement, or the heel of the shoe is used to press the earth about the plant. For hand planting, the plants are dropped ahead of the 'dibblers' by boys and girls. Seven thousand to ten thousand plants, or an acre, is an excellent day's work for a planter when everything is in good condition. Where a few hundred plants are set in the garden it is always desirable to water them before closing the earth about the plant.
Under reasonably favorable conditions a machine will plant from three to four acres a day. In addition to being labor savers, these machines do the work better and more uniformly than it is ordinarily done by hand. The plants can be set without the use of water, but the results are more satisfactory where the water is used.
The methods of handling a crop of sweet potatoes do not differ materially from those employed with ordinary farm and garden crops.
Aside from planting and harvesting, the work of caring for a crop of sweet potatoes can be done almost entirely by the use of ordinary farm and garden tools.
The sweet potato is subject to injury from a number of diseases. Those diseases causing rot and decay are most prevalent and result in the greatest loss during the period that the crop is held in storage, Occasionally, however, the crop may be lost before harvesting, and one form of rot, known as black-rot, destroys the young plants, attacks the potatoes while they are in the ground, and causes them to decay while in storage. The spores that are responsible for the several forms of rot affecting sweet potatoes may remain in the soil from year to year, or they may be carried over winter upon the seed. Diseases are generally introduced with affected seed or plants, and when once established in the soil, the storehouse, or the propagating bed it is doubtful whether they can be eradicated except by the adoption of the most thorough methods.
A disease known as stem-rot causes the stem of the plant to begin to die at the surface of the ground. This decay gradually extends downward to the potatoes and frequently kills the entire plant.
The diseases known as soft-rot, dry-rot, and white-rot are all similar in their method of attack to the black-rot. One form, known as soil-rot, causes the loss of the crop while it is in the field. Each of these diseases is caused by a particular fungus, but has received the common name suggested by its general appearance or some marked characteristic. Any one of the diseases of the sweet potato may be present without causing severe loss provided conditions are unfavorable to its development, and growers should be constantly on their guard to prevent the spread and development of diseases.
A system of crop rotation by which the land will not be planted to sweet potatoes oftener than every four or five years is the first step toward disease control. Care in the selection and keeping of potatoes intended for propagation is of importance, while clean cultivation and proper handling at the time of harvesting are essential. Diseases will generally make their first appearance upon cut, broken, or bruised potatoes, and all that are in any respect injured should be stored separately from the seed and perfect stock. The storage house should be cleaned and fumigated with sulphur or formalin before storing begins, and all crates or baskets used for handling the crop should be in the house during the fumigation.