Potato

Excerpt: A farm crop grown for its tubers, which are used largely for human food and for stock-food, and for the manufacture of starch and alcohol.


Plate XIX. A form of potato much prized for household use.





POTATO.
Solanum tuberosum, Linn. Solanaceae. (Irish, English, Round, White Potato.) Figs. 741-762.


By S. Fraser.


Plate XIX. A form of potato much prized for household use.

A farm crop grown for its tubers, which are used largely for human food and for stock-food, and for the manufacture of starch and alcohol. The genus Solanum comprises perhaps 1000 spe­cies, in many parts of the world. Some twenty of the described species are more or less tuber-bear­ing, but J. G. Baker (Journal Linnaeus Society, XX) considers that only six of these "possess a fair claim to be considered as distinct species in a broad sense." These six are Solanum tuberosum, S. Maglia, S. Commersoni, S. cardiophyllum, S. Jamesii, S. oxy­carpum. Of these, only S. tuberosum is known agri­cuturally. It is possible, however, that S. Maglia (the Darwin potato) and S. Commersoni (Fig. 103) possess value for the cultivator, either directly or hybridized with the common potato. S. Cammer­soni is now receiving considerable attention in Europe. It is native in Uruguay and Argentina "in rocky and arid situations at a low level." S. Maglia is native in the coast regions of Chile, while S. tuberosum occurs natively in the hill country of the interior of Chile and Peru. Forms of S. tuberosum occur in Mexico, an one of them (var. boreale) is native as far north as southern Colorado.


Fig. 742. Sprouts arising from the buds, or eyes, of a potato tuber.

The potato is perennial by means of its tubers. Its smooth, generally solid, more or less quadrangular stems attain a height of two to five or more feet. The stems bear com­pound leaves of oval leaflets and small intermedi-
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ate leaflets. The flowers are in clusters and have a five-pointed, wheel-shaped corolla, one to one and a half inches in diameter and varying in color from white to purple. (Fig. 741.) Stamens 5; pistil 1, 2-celled. The fine fibrous roots penetrate the soil to the depth of two to four feet, and frequently ex­tend horizontally two feet distant from the stems. The fruits or seed-balls are globular, three-fourths to one and one-half inches in diameter, and green, yellowish or purple in color. (Fig. 762.) The tuber is an underground stem; it bears buds, and, when planted, tends to produce plants similar to its parent; hence tubers are used for perpetuating a variety, and such are generally designated "seed tubers" or "seed."

Varieties vary considerably in composition; an average of many analyses is: Water, 75 per cent; protein, 2.5 per cent; ether extract, .08 per cent; starch, 19.87 per cent; fiber, .33 per cent; other non-nitrogenous materials, .77 per cent; ash, 1 per cent; undetermined, .45 per cent; 85 to 95 per cent of the total dry matter is digestible.

History of the Potato.

The potato was thought by De Candolle to have been in cultivation in Peru for probably 2,000 years. G. de la Vega found the Peruvians cul­tivating it in 1542. He sent tubers to Europe. Various importations were made by the Spanish, and the potato became known in parts of Europe before it was introduced into Ireland in 1586 by


Fig. 743. Potato, to show manner of growth.

Thomas Herriot, who was a member of the expe­dition sent to America by Sir Walter Raleigh. The Virginian colonists probably secured potatoes from the Spanish, and they soon proved a valuable acquisition.

It is a common opinion that the aborigines of Virginia cultivated the potato at the time of the discovery. W. R. Gerard asserts, however ("Scien­tific American," September 15, 1906), that the openauk of Thomas Herriot (a product much quoted or discussed in the later writings on the potato), supposed to have been the potato, is really the ground-nut, Apios tuberosa. He contends that the potato was secured by Raleigh's expedition, under his cousin Sir Richard Grenville, on the return voyage, from a Spanish ship hailing from St. Domingo and captured in mid-ocean. The potato was cultivated in Ireland long before it was known in England. Probably the potato was served as an exotic rarity at a Harvard installation dinner in 1707; but the tuber was not brought into cultivation in New England till the arrival of the Presbyterian immigrants from Ireland in 1718. The potato of Shakespeare was what we now know as the sweet-potato, which derived its name from the aboriginal word botata or batata; this word or its derivative was later applied to our common or Irish potato. The aboriginal word is still preserved to us in the Latin name of the sweet-potato, Ipomaea. (or Convolvulus) Batatas.


Fig. 744. Phyllotaxy of the potato. The inserted tacks show the location of the buds.

Gerarde's Herball, published in 1597, describes the potato, and the edition published in 1636 con­tains a woodcut of it. Many of the other works of like nature contain descriptions of it. In 1663, the Royal Society of England tried to popularize the plant, especially in Ireland. So late as 1699 Evelyn barely mentioned the potato, and in 1719 London and Wise did not consider the plant worthy of listing in their Complete Gardener. Only two varieties were listed in 1771, yet by the end of the eighteenth century they were numerous.

Potato-culture spread slowly in Europe but more rapidly in the south of Ireland, because the peas­ants realized that it was a useful food and planted it everywhere; and with this as their commis­sary they were able to maintain the opposition to English rule. Two and a half centuries of reliance on this crop led to the neglect of other crops, and, when the blight occurred in Ireland in 1846, it was attended by one of the worst famines known in Europe. The potato has been more highly devel­oped in Europe than in America, and much higher average yields are secured in the United Kingdom and northern Europe than in this country.

Geographical distribution and extent of the potato.

Next to rice, the potato is probably the most extensively grown and most valuable crop in the world. The annual yield of the world is nearly five billion bushels. The potato crop of Europe in value and volume exceeds the tabulated wheat crop of the world. One acre of potatoes fre­quently furnishes as much human food as ten acres of wheat, and wherever wheat is a precarious crop, as in northern Europe, potato-grow­ ing has been extensively developed. Yields of 1,000 to 1,200 bushels of potatoes per acre con­taining 10,000 pounds of starch are on record. About 30,000,000 acres of potatoes are grown an­nually in Europe, and of this area one-third is in Russia, the average yield per acre being about 95 bushels; Germany is second in total area with 8,000,000 acres and a yield of nearly 1,600,000,000 bushels, an average of 200 bushels per acre. France grows between 3,500,000 and 4,000,000 acres, Austria nearly 3,000,000, Hungary 1,500,000 and the United Kingdom 1,250,000. The average yield of England is about 230 bushels per acre, that of Ireland about 150 bushels. The United States grows about 3,000,000 acres, and the average yield for the past ten years is 84.5 bushels. Since the potato thrives best in a cool climate, potato-growing has been developed to the greatest extent in the Northern states. (Fig. 745.) According to the report of the Twelfth Census, the five states reporting the greatest number of bushels in 1899 were New York, 38,060,471 bushels; Wisconsin, 24,641,498 bush­els; Michigan, 23,476,444 bushels; Pennsylvania, 21,769,472 bushels; and Iowa, 17,305,919 bushels. Fig. 746 shows the average yield per acre in bushels for the period 1900-1904.

In Canada, the potato crop has always been important, although the output has not shown so great an increase as some other crops, notably oats and wheat. In 1871, the potato crop was 47,330,187 bushels. In 1901, it reached 55,362,635 bushels, raised on 448,743 acres. The production in bushels


Fig. 745. Potatoes. To show actual yield in bushels by states.

by provinces in 1901 was as follows: Ontario, 20,042,258; Quebec, 17,135,739; Prince Edward Island, 4,986,633; New Brunswick, 4,649,059; Nova Scotia, 4,394,413; Manitoba, 1,920,794; The Territories, 1,277,793; British Columbia, 955,946.

Culture of Potatoes.

Soil.

The soil usually considered best is a deep, mellow, free-working loam, although crops are raised on lighter or heavier soils, provided the latter are well drained. Fall-plowing is generally advisable, since it facilitates the spring work. It should be as deep as possible, to a depth of twelve inches if the soil will permit. The land is generally left rough-plowed during winter and is fitted as early a s possible in spring. The seed­ bed should be well prepared by using the disk or acme harrows.

Fertilizers.

An application of ten tons or more per acre of barnyard manure may be made in the fall before plowing, or, if the manure is well rotted, it may be applied in


Fig. 746. Potatoes. To show the average yield per acre in bushels for the five year period, 1900-1904. Compiled from Yearbook United States Department of Agriculture.

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spring and disked in. It is important for potatoes that there be plenty of humus, hence the crop is frequently grown after a crop of clover or on a two­ year-old sod. It would do well after a much older sod, but there is likely to be trouble from wire­ worms and white grubs; for this rea­son, when po­tatoes are to be planted on


Fig. 747. A "long" potato, with shallow eyes; peels with little waste.

such land it is considered advisable to follow another crop, such as oats or corn, by potatoes, which may then be grown for two or three successive years if desired. If com­mercial fertilizers are applied, generally a complete fertilizer--containing nitrogen, phosphoric acid and potash--gives best results. Nitrate of soda is a good source of nitrogen for potatoes.

Seed potatoes.

The seed tubers may be planted whole or cut; a piece weighing about three ounces, or as large as a good-sized egg, and having at least one good eye, being the most profitable. It pays to dig the heaviest-yielding plants by hand and save their progeny for seed. Heavy-yielding plants will gen­erally reproduce heavy yielders, and vice versa. The tubers used for seed should be sound, free from coarseness and second growth and be true to name. If planted in rows thirty-six inches apart and the plants fifteen inches asunder in the row, it will require about seventeen bushels of seed per acre.

The storage of seed is a very important factor. It should be kept in a cool, well-ventilated place to prevent much loss of weight, until ten or four­teen days before planting time, when it may be spread on the barn floor or in some well-lighted place, which will cause the seed to begin to grow before planting. The shoots made under such con­ditions will be very small. If the seed is scabby, or from scab-infested land, it may be treated with formalin. [See next page under Enemies.]

Seeding. Planting potatoes

Planting may be done by hand or machinery, the latter being by far the cheaper way, although still unsatisfactory, because there is no planter, known to the writer which will handle a seed piece of the size required. On sandy loam soils the seed may be


Fig. 748. A "long" potato, difficult to peel economically.

planted three or four inches deep, and level culture adopted with profit. Under other condi­tions, planting two or three inches deep and subse­quent drill culture may be good practice. Where irrigation is practiced, rows are often four feet apart, but under other conditions three feet is generally considered ample.

The time of planting depends on whether an early, mid-season, or late crop is being grown. Generally the early crop is put in as soon as settled weather comes and the ground is workable. Care must be taken that the plants are not frosted, as they are sensitive. The late crop is planted in the middle or latter part of May in the North. [The planting dates throughout the country are given in Chapter VII, pages 138-140.]

Subsequent care.

Cultivation begins a few days after planting and consists of harrowing the land with the spike-toothed harrow or the weeder to destroy all weeds before they are well started, a policy that should be rigidly maintained. The weeder may then be used once a week until the plants are seven to ten inches tall. By this time the plants may have been cultivated once, with the cultivator set three or four inches deep; they should receive subsequently about four more culti­vations, each one shallower than its predecessor, the second one being not more than two to two and a half inches deep, thus giving a total of about five cultivations at intervals of seven to ten days. By this time the tops will meet in the rows.

Varieties.

In choosing a vari­ety to plant, a number of factors must be consid­ered. Among these may be men­tioned:
(1) Good cook­ing quality and flavor. These are partly influenced


Fig. 749. A "round" potato, with shallow eyes.

by the soil, season, fertilizers, ability to mature before frost and other factors.
(2) Yield. This is dependent on adaptation of the variety to its environment.
(3) Ability to resist diseases. No blight-proof variety exists, but some possess more resistance than others.
(4) Color of skin and tuber. Some markets re­quire one color, others another.
(5) The nature of the skin. A netted or rough skin is preferred.
(6) The shape. Some markets discriminate in favor of a particular shape. Varieties are some­ times classified according to shape, as round, flat round, kidney and the like.
(7) Depth and frequency of eyes. Deep and numerous eyes are not economical in peeling.
(8) Time of maturity. In the northern states varieties are classified according to the time taken to form salable tubers; thus, "earlies" are ready to harvest in 70 to 90 days after planting, "second earlies" in 90 to 130 days, while late varieties may sometimes continue to grow for 200 days.
(9) The character of the foliage and top. Straight upright stems bearing thick hard leaves are desired. since such are probably less liable to diseases, and are easier to spray.
(10) The vigor. The variety and the strain se­cured must be vigorous and not subject to second growth of the tubers.
(11) True to name. The variety should be what it is purchased for.

Many thousand varieties of potatoes have been developed during the past hundred years. Among prominent varieties of today may be mentioned:


Fig. 750. Beginning of late blight on left. Right spray good, but showing a few holes made by flea-beetles.

Earlies: Bliss Triumph, Early Ohio, Six Weeks Market, Early Thoroughbred, Bovee, Reliance, Crown Jewel, Noroton Beauty, Burpee Extra-Early, Eureka, Early Rose (some strains). Second earlies: Burpee Extra-Early, Eureka, Beauty of Hebron, Polaris, Irish Cobbler, Early Rose (some strains). Late: Carmen No.3, Sir Walter Raleigh, Rural New Yorker No.2, Vermont Gold Coin, State of Maine, Green Mountain, Freeman, Burbank.

Potatoes sometimes sport or "mix" in the hill, and these bud-sports may be treated as new varie­ties. Practically all the new varieties of potatoes, however, are produced from seed, for every seedling is likely to be different from the parent. Seed-balls are not produced abundantly on most varieties. If it is desired to produce new kinds, the seed should be saved and treated as tomato seed is treated, being planted the following spring. The first year the plants are small and slender, and the tubers will also be very small. These tubers are saved and planted the next year, when a crop of good-sized tubers may be expected, showing their characteristics. If it is desired to combine features of two varieties, the flowers may be crossed; and the resulting seed will produce hybrids.

Harvesting and storing potatoes.

Early potatoes are dug as soon as large enough for sale. Late varieties are left until the vines are dead; should the vines be killed by blight and it is intended to store the tubers, the digging should be delayed, if possible, until ten days after the date the vines died. The grower should harvest when the land is dry, pick up the tubers at once and keep them cool. In stor­age the tubers should be held between 32° and 40° Fahr., be well ventilated and kept dark.


POTATO 523

Potatoes may be stored in the open, in piles covered with straw and earth, in cellars or root­ houses according to the climatic conditions. In the northern states the cellar is the most advan­tageous, since the conditions can be more easily controlled, and the crop may be inspected or sold at any time. The cellar should be kept dark. With sound tubers, the loss in weight in storage may vary between 5 and 20 per cent in the five winter months. Both temperature and the moisture con­tent have an influence, a high temperature increas­ing and a high moisture content diminishing the loss. Nobbe found that about 75 per cent of the depreciation is loss of the water content.

Potato Enemies.

Potato Diseases.

In the northern and north-central states the two most serious diseases are the early and late blights. The early blight (Alternaria solani) is a fungus which attacks the leaves, enter­ing frequently through holes made by flea-beetles. It comes on earlier in the season than the late blight and does not cause rot of the tubers. The late blight (Phytophthora infestans, Figs. 750, 751, 752), another fungous disease, injures and often destroys the leaves, stems and tubers, and is prob­ably familiar to most growers. These diseases spread by means of spores which germinate on the potato leaves and stems and produce the fungus that causes the diseased appearance. If the leaves and stems be kept coated with some fungicide, as Bordeaux mixture, it prevents the germination of the spores and helps to check the spread of the disease.

Potato rosette attacks the stem, causing the leaves to grow in clusters. It reduces the yield in many parts of the country. The disease is caused, in part at least, by Corticium vagum solani (Rhizoctonia solani). One form of this fungus develops scale-like bodies on the tubers, causing the "black scale" of potatoes.




Fig. 751. Shoot killed by blight.

Scab (Oospora scabies) is a fun­gous disease which appears on the tubers. For treatment, the seed tubers should be immersed for two hours in a solution of formalin of the strength of one pound of formalin to thirty gal­lons of water. If the seed is not planted at once, it should be spread thinly to dry, and should be planted on scab-free soil.

Dry-rot (Fusarium oxysporum). -This disease attacks all parts of the plant below ground and produces a gradual premature death of the plants. Infected tubers rot and shrivel. This fun­gus causes more or less loss to the potato crop in all sections of the United States.

A good and rather long rotation of crops is of value in combating all of these diseases.

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Insects.

The flea-beetle (Crepidodera [Epitrix] cucumeris) attacks the leaves, puncturing them and thus furnishing an easy entrance for spores of dis­eases. Spraying with Bordeaux mixture as soon as the insects appear is of value. It acts as a deterrent. On the Pacific coast other flea-beetles occur, and for such the use of arsenites alone or in Bordeaux mixture is advised.




Fig. 752. Distribution of late blight (Phytophthora infestans) of potato indicated by lines, and of cot­ton-wilt (Neocosmospora vasinfecta) indicated by dots. Yearbook, Department of Agriculture, 1903.

The potato-bug or Colorado potato-beetle (Do­ryphora decemlineata, Fig. 753), the larva of which attacks the foliage, is destroyed by spraying with Paris green or some other arsenite in a solution, preferably Bordeaux mixture, using one-fourth to one-half pound of Paris green to fifty gallons of solution, and applying 150 to 200 gallons per acre when the foliage is well grown.

The old-fashioned potato-bug or blister-beetle (Epicauta vittata) is combated in the same way as the Colorado potato-beetle. It is now rarely seen. The potato-worm (Gelechia operculella) is injurious on the Pacific coast. The potato-stalk weevil (Tricho­baris trinotata) attacks the stems. It is found from Canada to Florida.

Uses of the potato.

In the United States, potatoes are used almost entirely as human food, a few million bushels being used for the manufacture of starch. They may be desiccated and in this form can be readily trans­ported. In Europe, large quantities are used for the manufacture of starch and alcohol, the latter being a cheap source of power for motors. Pota­toes are also used as a stock-food, either raw, cooked or as silage. [For the making of alcohol, see Part II of this volume.]

Marketing of the potato.

Potatoes are sold by the pound, peck, bushel, barrel, cental, sack and car lot. The bushel box is the most convenient package for a home market. The barrel and sack are often used in shipping. The potatoes must be graded before shipment and all small, diseased or ill-shaped tubers sorted out. Eight to 10 per cent commission is usually charged by salesmen in New York, Philadelphia and other markets. When potatoes are shipped any distance by rail, it not infrequently happens that of the price paid by the consumer for a bushel of potatoes about two­ thirds is required to defray the cost of transportation and distribution, and one-third is left for the grower.

Machinery.
(Figs. 754-760.)

Potato machi­nery is in a much less satisfactory condition than that used by the grain- or hay­ grower. There are no potato planters which will plant all the tubers all the time unless a man sits behind to look after them; 80 to 95 per cent perfect is the best that has been attained automatically. Few of the potato spray­ing machines carry enough nozzles to ensure the covering of the whole of the plants with the spray. With potato harvesting machinery the aim has been to supply a two-horse machine, and in some cases these are efficient, but in some soils three or four horses are necessary to handle the same machine. The shovel plow is not an efficient tool and is of little value for the commercial grower. The elevator diggers, of which there are several makes, are a distinct advance. There are two types, the high elevator, in which the potatoes and soil are lifted to a height of two or more feet up an inclined plane and shaken meanwhile, and the low elevator, in which the soil and potatoes are elevated very little, but are passed backward over disk-like rollers.




Fig. 753. Potato-beetle (Doryphora decemlineata).

In spite of defects, any commercial grower who has ten acres of potatoes needs a planter, sprayer, cultivator and digger of the most approved types. With a good planter a man can open, distribute the fertilizer, plant and cover three to six acres per day, and by changing teams during the day the machine may be run at the maximum figure. A weeder will cover twenty acres a day once. With reasonable facilities for filling, a spraying machine taking five rows should cover one to one and a quarter acres per hour of work, or about ten acres per day, once over. A two-horse cultivator set to take two rows will cover eight to ten acres per day, going once in a row. A man without machi­nery will dig one-eighth to one-half an acre per day, depending on the crop and the soil, at a cost of two to six and sometimes eight cents per bushel; with a good mechanical digger and three or four horses and eight to sixteen hands to pick up, three to six acres may be dug per day at a cost not exceeding two cents per bushel.

A specific example.

While the average yield of potatoes in the United States is less than ninety bushels per acre, it is wholly practicable, on good potato soil, to produce three to five times that yield. It is doubt­ful whether it pays to raise less than two hundred bushels to the acre. Whether it pays to raise more than three hundred bushels depends on the price of labor and the ability to secure it advantageously. By superior tillage, the yield may very easily be placed beyond three hundred bushels, if the land is right; but if this requires the keeping of an extra team throughout the year in order to have it when


Fig. 754. A potato planter in cross-section.

the potatoes need tilling, it is a question whether the crop would return a profit. The question of farm organization at once arises, for there should be other productive work for the extra teams and men at other times of the year.

The farm methods employed in producing more than four hundred bushels of potatoes to the acre on a particular farm (T. E. Martin, West Rush, New York) will illustrate the discussion in this article. The land (good loam) is in a three-year rotation,--wheat, clover, potatoes. Potatoes is the money crop. The land is underdrained. Plowing has been lowered gradually from six to ten or twelve inches. The plowed land is rolled, and then deeply harrowed three or four times. When necessary, parts of the land are rolled again and worked over several times with harrows. Home-mixed fertilizer is drilled in at the rate of 1,600 pounds to the acre, so mixed as to contain 2 3/4 per cent nitrogen, 9 1/4 per cent phosphoric acid, 15 per cent potash. Counting the mixing, the fertilizer costs about thirty dollars per ton. The soil is considered to be deficient in potash.



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The potatoes are planted on a rolled surface in order to secure uniform depth and a good stand. The rows are thirty-six inches apart, seed placed three inches deep, and about eleven inches in the


Fig. 755. Potato planter.

row, requiring sixteen to twenty bushels of seed, cut to one or two eyes. Rows are placed at three feet in order to facilitate spraying. On high-priced truck-garden land, closer planting may be advis­able. The tubers are planted with an automatic cutting, dropping, furrowing and covering machine.

The fields are tilled ten to fifteen times. With the good preparation of land and efficient tools, this extent of tilling is not laborious nor expensive. Level culture is practiced, but considerable ridges are formed by the time the vines cover the ground. A riding double-row cultivator and one­ horse weeder are used. Tillage invariably begins within a week after planting, by following the potato-row lines. The first and second times over, very narrow teeth are used, set deep. The third and fourth tillings are made as soon as the rows can be followed, working deep and very close to the plants. Immediately following the fourth cul­tivation, the weeder is used, as a rule, running twice over the field, crosswise and lengthwise, the lengthwise treatment pulling the plants up straight so that subsequent working is not interfered with. Seven-inch side teeth are now used on the cultivator, throwing a small, sharp ridge directly on each row, burying the weeds. The fields are hand-weeded once or twice; and, in this operation, all weak, diseased or prematurely ripen­ing potato plants are pulled up, being treated as weeds.

Spraying is accomplished by means of a two­ wheeled geared machine, developing sixty to eighty pounds pressure and carrying the nozzles ahead of the wheels. On eighteen acres in 1906, there were used 331 barrels (of fifty-five gallons) of Bordeaux mixture, entailing a cost per acre for spraying of twelve dollars. Careful tests showed that the spraying saved, above its cost, about forty dollars


Fig. 756. The platform of one of the planters.

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per acre. Spraying began July 2 and was com­pleted September 10. The area required about one ton of sulfate of copper in crystals, and fifteen barrels of stone lime. The formula is six pounds of sulfate, six pounds of lime, fifty gallons of water; also two pounds of Paris green per acre are added. Each application is made in opposite directions, two such sprayings being called a double application. From the time the vines cover the ground, at the beginning of each double application all nozzles are directed to the right, then into the centers twice over and then to the left twice over. This plan requires three double applications, and the spray is directed against the plant from six different posi­tions and angles; at the completion of the sixth spraying, every part of the plant is copper-plated.

The last week in September or the first week in October, while vines are still green, harvesting is


Fig. 757. Four-row potato sprayer.

begun. A four-horse elevator digger is used. In 1906, the crop on eighteen acres was dug and picked up in six and one-half actual days, the total crop being 7,510 bushels, or 417 bushels to the acre. (Fourteen years previous, when Mr. Martin took the farm, the average yield was sixty bushels per acre. A good part of the above crop was hauled directly to the station and sold at forty cents; 136 bushels only were sold as low as thirty-eight cents). The heav­iest day's work in the harvesting in 1906 was as follows: Twenty-one helpers, little and big; three and three-fourths acres dug and picked up; three two-horse rigs drew seventeen loads to cars one mile distant, comprising 1,011 crates; digging teams drew 283 crates on trucks to the barn; at six o'clock there were left on wagons and in the field 207 crates; total 1,501 crates. A break-down in the digger caused delay of one hour and loss in handling of 200 bushels.




Fig. 758. Potato digger; low elevator type.

Potato tops are all raked and burned immediately to destroy disease. The ground is worked about twice with the spring-tooth harrow and sown di­rectly to wheat, after applying about 400 pounds of


Fig. 759. Potato digger; high elevator type.

home-mixed fertilizer. Eight quarts of choice tim­othy seed is drilled to the acre at this time. The following spring, clover or alfalfa, or both, is added.

In such high-class potato-growing as this, special attention must be given to the stock seed. A "seed piece" of two acres is grown according to the very best approved methods. This area is planted with the choicest large tubers, and all inferior plants are eradicated as rapidly as their deficiencies become known. Very promising hills are saved for stock seed the following year. This "seed piece" or field supplies the tubers for raising the main potato crops.

European experience.

The potato crop assumes great importance in Europe, partly because the corn plant is not suc­cessful, and the potato is the cheap starch-producing plant.


Fig. 760. Potato sorter.

It is the standard crop for starch and alcohol factories, is the staple food of the poor, and is much fed to stock. The aim, as compared with American po­tato-growers (and reported for this article by L. R. Jones), is for a product adapted to one or another special purpose, and for a large yield quite irrespective of the seed or labor invested. Careful attention is paid to the seed, which is generally secured from more northerly countries. The crop from the best northern-grown seed is con­sidered more disease-resistant and more productive, The origination of new varieties has been espe­cially stimulated during the last two decades in Great Britain and Germany, in order to meet the more specialized demands. Seed­ balls are more abundant, owing probably to climatic conditions, and hence less difficulty is expe­rienced in crossing varieties. In Great Britain, where potatoes are grown primarily for table use, the ideal tuber is white-fleshed, rich in starch, medium size, oval, smooth and with shallow eyes. Much attention is given to securing increased disease-resistance. On the continent the ideal table variety is smaller, yellow-fleshed, relatively poorer in starch and richer in proteids. The breeding of starch-rich varieties for stock-feed and factory purposes has received attention, especially in Germany and Austria.