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.
There are a great many superstitions and prejudices in regard to the potato. Some are as old as time but, generally there is no good reason for their existence.
Planting "in the dark of the moon" is a popular fallacy. Some argue, and often can relate, experiences that to them seem to prove that potatoes will not make a satisfactory crop unless planted during that part of the month when the moon does not shine. If planted when the moon shines at night, the belief is that the plant goes "all to top" and will not make tubers. Others will argue that the planting should be done "in the light of the moon" in order to give the plants a good start, because of the additional light. There are experiences to prove that both are right. There is of course no foundation for such notions, and potatoes make good crops if soil and moisture conditions are right, regardless of the moon.
Cutting off the seed end," or terminal bud, is a practice supposed to result in benefit to the crop. The young potato plant is started and nourished by the plant food stored up in the tuber. To throw away any part of the potato is to destroy food that could be used to advantage. The reason given for doing it is to keep too many eyes from starting, but experience shows that if the seed is strong and has been well stored and handled, the sprout from one strong bud dominates and the others remain practically dormant. The terminal bud is the one found first, and European growers consider it the most important part of the seed tuber, and it normally starts first.
Cutting seed to one eye," or two eyes, or some other number, is supposed by some to carry a mysterious charm that will affect the crop. All there can be of importance in this notion is that the larger the seed piece the greater supply of nutriment available for starting the new plant.
To irrigate when potatoes are in bloom' is a practice relied upon by growers in some irrigated sections. This may or may not be the right time, depending on the condition of the soil. The time to irrigate is when moisture is required by the plant, regardless of anything else.
Do not use manure on potato land, it makes scab,' is a belief so strong in the minds of soine growers that the crop is grown continuously on land without manuring until it becomes impoverished. It is probably true that fresh manure applied to land immediately preceding the planting of potatoes furnishes conditions favorable to the growth of the scab bacteria, but when used in a rotation, as on the grass crop that precedes potatoes, manure, especially when well rotted, is a benefit. Growers in Europe place great dependence on its use.
To plant potatoes on Good Friday" is believed by some people to insure the crop, regardless of the conditions. If all conditions are right, it would be as well to plant on this day as any other, but no better. Soil and climatic conditions must be the guide for time of planting.
Color and shape are factors that govern some markets. For instance, on the Pacific coast the demand is for a long, white potato; Denver and Colorado Springs pay a premium for red potatoes; in England, kidney shaped varieties are in highest favor, and nowhere are blue-skinned varieties popular except in Spain. As a matter of fact, any good potato is good food; there is no more reason for these discriminating prejudices than for white eggs to sell higher in San Francisco than brown, and vice versa in Boston.
That potatoes grown on irrigated land" are not of good quality and flavor is sometimes believed.
Moisture is one of the essentials in the production of the potato crop, and with irrigation the supply of moisture can be kept even and sufficient to grow a product of the greatest possible uniformity and quality. It depends entirely on the grower. A potato grown from start to maturity without a check is produced under the most ideal conditions.