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Minnesota, &c., &c., where the soil is appropriate and the culture careful, the sort may probably last, in a good degree of vigor, a half century or more. But where the climate, soil and culture are inferior, the duration will be very much shorter. I view the question in precisely the same light as that concerning men and brute animals in the same varying conditions. 74. I had intended to add an eighth part here, containing illustrations of many points laid down above, especially in relation to hardiness. These illustrations would have been drawn from a history of some of my most important families of seedlings referred to in Nos. 8-10 above. But my strength is inadequate, aad this article is complete without it

THE POTATO.

ITS DISEASES WITH INCIDENTAL REMARKS ON ITS SOILS AND CULTURE.

INTRODUCTION.

1. It is now twelve years since my last considerable essay on the potato was published (see the "New York Agricultural Transactions" for 1851, pp. 365-402). In the interval I have done nearly all my work of originating and testing many thousands of seedlings. The public have gratefully appreciated the value of these labors.

2. The experience of these years has fully confirmed the positions taken on the subject of disease in my previous articles (see "New York Agricultural Transactions" for 1847, pp. 425-460; for 1848, pp. 403-426, and those for 1851, noticed above).

3. This continued experience has brought to light few new truths; but many valuable illustrations have arisen which the agriculturist may be glad to contemplate, and all the more, because connected with my acknowledged success in the origination of new and valuable varieties.

4. Through all these years I have kept a running record of important facts and suggestions on the culture and disease of the potato, in the hope of one day finding time and strength to digest the whole in an extended treatise, but in the continued decline of my health, that hope is fast fading. 5. The present work is written out of the fullness of the subject, as it lies in my mind, with little reference to those recorded stores of experience. 6. I am the more strongly induced to write now, because recent efforts have been made, both in Europe and America, to revive the early theory that the fungus, rast or mildew, which usually precedes the disease of the tubers, is the main cause of the disease rather than the natural consequence of disease already existing in the plant.

7. These efforts seem, so far as our own country is concerned, not only to ignore what has been written generally on this subject of disease, but also what has been written specifically to sustain this very theory.

8. The grand error, as it seems to me, of nearly all who have written on this topic, is that theories got up in the laboratory after a hasty inspection of the crop, have ruled the writers, rather than long and varied experience in the field of culture.

9. At the time Prof. S. W. Johnson, of New Haven, published his four articles on this subject, I was in too feeble health to read them attentively, much less to review them. The time for such review has now measurably passed by. The leading positions of this article are all in contravention

of his views, and are, as it seems to me, at least a sufficient answer to them. His articles may be found in the Country Gentleman for January 22, April 2 and 16, and June 4 of 1863.

10. Since my article in the "New York Transactions" for 1851 was published, very numerous theories and remedies have been published in both Europe and the United States, nearly all of which I have noticed in the successive volumes of the Country Gentleman. They are scarcely of sufficient importance to be distinctly referred to here. Prof. Johnson notices some of the proposed remedies, to which I refer, in his fourth article.

THE POTATO.

I. ITS PECUNIARY VALUE.

1. According to the census of 1860, the amount of this crop was 110,571,201 bushels. The department of agriculture estimates the crop of 1862 at 114,500,000 bushels. By the first of these estimates, 99,000,000, or nearly nine-tenths of the whole, was grown in the Free States. Of these, New York raised 26,447,000 bushels, or almost one-fourth of the whole amount; Pennsylvania, one-eighth; Ohio, one-twelfth; Maine, one-seventeenth, and Illinois, Michigan and Vermont, each one-twentieth of the whole sum. The remainder were produced in the other States in much smaller proportions.

2. Taking the medium between the two preceding estimates, and calling the crop 112,000,000 bushels, and estimating it worth, on the average, twenty-five cents per bushel, we have the cash value of the crop $28,000,000. Among the edible vegetable productions of our country, potatoes rank fourth, after wheat, corn and oats being more valuable than peas, beans, buckwheat or rice.

II. PECUNIARY LOSS BY DISEASE.

3. The amount of loss to the United States, by potato disease, supposing that for the last twenty years the loss has averaged one-tenth of the whole crop, would be $2,800,000. In many years of severe disease it has probably amounted to one-fifth of the whole crop, or $5,600,000. The loss in Great Britain in some of the early years of the pervasion of the disease, was reckoned as high as $50,000,000 in a single year. Great as this loss may seem, it is not probably proportionally greater than that by rust on wheat and oats in certain seasons, nor than that by cold wet seasons on corn and apples, and many other kinds of fruit and most tropical plants cultivated among us.

III. THE PECULIAR VALUE OF THE POTATO AS AN ARTICLE OF FOOD. 4. As an article of food the potato compares better with bread than any other edible vegetable grown in temperate or cool climates. Like bread it is farinaceous, free from marked taste and color, and thus is fitted to be cooked and eaten with almost any other variety of food. Its farinaceous character fits it to almost every degree of human health, Its gradual introduction into use as an article of food among civilized nations, about

three hundred years ago, has justly been considered an era in human happiness and progress.

5. As its nutritious elements consist principally of starch, with a little gum, mucilage and sugar, while it has only a small proportion of phosphates, it is fitted to be the accompaniment of meat, bread and milk, rather than a substitute for them.

6. Thus it is the most acceptable of all esculent roots, having been, until the era of disease, the most easily and cheaply cultivated. It was thus an indispensable luxury to the rich and an equally indispensable necessity to the poor, in all temperate climates.

IV. RELATIONS OF THE POTATO TO CLIMATE.

7. The potato is a native of the tropical mountain ranges of South America, particularly of the lower ridges and high table lands of the Andes; growing there in connection with a grain called quinoa and the nasturtion, far above the position where the common grains and grasses of Europe and the United States can be cultivated. It is thus a tropical or semi-tropical mountain plant.

8. Its mountain origin in the tropics fits it to the climate of lower mountainous districts in the warmer portions of Europe and the United States, and for the plains of high northern latitudes in both hemispheres. Hence it flourishes well on the southern shores of Lake Superior, on the Red River and on the Columbia.

In Europe, where the isothermal line runs much further north than in the United States, it is found at the northeast corner of Iceland, and in Asia, at Yakoutsk, on the river Lena.

9. As a perennial plant, each variety of potato has a fixed period of growth and maturity from which it does not vary ordinarily any more than a cherry or an apple. Its adaptation to longer or shorter seasons must result from its reproduction from the seed-ball, and the subsequent selection of sorts adapted to the season of any particular latitude; some sorts maturing in twelve weeks, and some few sorts varying probably as many months. 10. A mountain tropical has a two-fold sympathy.-First, as a tropical simply, it is injured by frost and needs a certain uniformity of weather for its healthiest growth. In this respect it is associated with corn, melons, tomatoes, cucumbers and other tropicals, in all to the number of sixteen to twenty, commonly cultivated in the Northern States. It requires, however, less heat than any of them except the nasturtion, and will bear irregularities of temperature better than any of them except corn and the nasturtion. 11. Secondly, as a mountain plant it requires a certain amount of coolness and moisture, and suffers from excessive heat, either dry or wet. In this respect it is closely associated with our ordinary grasses, grains and fruits.

In

12. This, its mountain tropical character, also exposes it to a double liability to diseases; on the one hand, to those which affect strictly tropical plants, and on the other, to those which affect northern hardy ones. this double liability it stands nearly alone, the grape being the plant most intimately, in this respect, associated with it, and that only in its cultivated condition.

V. THE LIABILITY OF THE POTATO TO DISEASE.

13. This liability did not exist, in Europe and the United States, in that marked degree that exercised general attention and alarm, until about 1843. The absence of exact records on this point, indicating the visible appearance and degree of injury which this crop may have suffered previously to twenty years ago, renders it unsafe making any assertion on this topic less qualified than the above.

14. The severity and almost universal exhibition of this disease from the beginning, and its perpetual recurrence since, under circumstances supposed by many to be capricious, have invested it in the judgment of many with the character of inscrutability. This conclusion may have arisen from the want of an enlightened and popular system of vegetable pathology. In the animal kingdom, a just physiology long since became the basis of a corresponding system of pathology: but although an equally enlightened system of physiology in the vegetable kingdom has been elaborated, it has not, so far as I know, resulted in a corresponding system of pathology. This failure, if I am right in supposing it to exist, has doubtless arisen from the fact that all such investigations are comparatively recent, and that relating to the animal kingdom being the first in importance, the time had not come, since the pressure of work on the scientific mind of the world, to give this subject a proper attention. It seems to me, at least, that almost all the wild theories on the subject of potato disease put forth during the last twenty years, may be traced to the absence, in the minds of the writers, of a simple and well-defined system of vegetable pathology.

15. Certainly the disease of the potato is incurable, so long as any of those varieties which have once been seriously affected continue to be used for seed, the disease never failing to recur under the recurrence of the conditions which first produced it. Among all the varieties in use twenty years ago, I do not know of one exempt from occasional disease.

VI. THEORIES OF THE DISEASE OF THE POTATO.

16. In the Patent Office Reports for 1848, pages 363-368, will be found a summary drawn up by Dr. Fraas, embracing the opinions of about seventy distinguished men on the potato disease. The causes are arranged under seven classes, viz: fungus, insects, extremes of weather and soil, degeneration, defective elements of the potato, abnormal conditions of the atmosphere, and excessive culture.

17. These seven classes contain, as I suppose, nearly the whole truth on this subject, mixed however with much error-the whole being in a form of little practical availability. As the theory of disease, hereinafter to be exhibited, was first given to the public in my essays of 1847 and 1848-a theory rigidly deduced from my own experience-I obviously could get no aid from this synopsis of opinions.

18. The great fault of most early writers on this theme, was that they did not sufficiently study nature's manifestations in the field, but gave the public too nearly the results of the study and laboratory. Where observations were made in the field they were not extended through a sufficiently long period of time, involving a great variety of phases of weather, the

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