V.

THE POTATO-ITS NATURAL HISTORY-DETERIORATION AND IMPROVEMENT.

Under the auspices of the New York State Agricultural Society, the Rev. C. E. Goodrich, of Utica, has devoted much time and research to the propagation and improvement of the potato; and his labors are regarded by the officers of said society, (very competent judges,) and others, as having developed facts of some importance in the course of experiments continued through several years. We copy from the proofsheets of the Transactions of the Society for 1852, kindly furnished for that purpose by its secretary, B. P. Johnson, esq., so much as is deemed of general interest and as our limits will permit.

The Rev. Joel Blew, of Howard county, Maryland, has bestowed considerable thought on the diseases of this tuber, and made experiments in cultivating it, from whom a communication has been received on the subject. Indeed, the "potato rot" is a fruitful theme, and no disrespect is intended in declining to fill the annual agricultural report from this Bureau with speculations more voluminous than profitable.

I. THE NATURAL HISTORY OF THE POTATO.

This subject is treated at some length in the Transactions for 1847, as before referred to. I here add some further facts:

A friend of the writer spent some time at Bogotá, a city of New Granada, situate upon the mountains, 8,500 feet above the sea, 5° of north latitude. During his residence there, in 1847 and 1848, he found the climate free from frost through the whole year. The thermometer never rises above 84°, nor sinks to the freezing point; nor does it ever vary more than 5o in any one day. There he found, as Humboldt had more than 40 years before, potatoes of the very best quality. The climate was found too cool for melons and many other tropical plants, which were brought on mules from warmer regions lower down the sides of the mountains. Here, too, many species of plants-as some varieties of peppers and cabbage-never cease growing. It is, hence, obvious that the potato loves a cool, uniform, and long season, the very reverse of what it finds here, where we frequently have a hot, unsteady, and short sea

son. Nothing but the greatest constitutional vigor could ever have sustained the potato in a prosperous growth in the same soil and climate that produces melons, tomatoes, corn, egg-plants, &c. We see, from the foregoing facts, the reason why the potato flourishes in Iceland, and even in Siberia. Wherever it has shortened the season of its growth, and finds a few weeks of summer weather free from frost, there it will mature a crop. We see, too, why, in this climate, the potato does best in elevated, and even mountainous districts, where it finds a cool position and moist, mucky soil.

II. THE TWO FOLD SYMPATHY OF THE POTATO.

1. As a simply tropical plant, it requires, like the most of its class, steady and uniform weather, but less heat than most of its associates. It fears not only frost, but all sudden and extreme changes. From such changes I think most of the diseases occurring in my experience before 1850 arose.

2. As a mountain tropical plant, it will not only bear, but requires for its best development, more air, moisture, and coolness than most other tropical plants. The nasturtium, however, is found growing on the mountains of South America, in company with the potato, beyond the limits of all other cultivation. Exactly in harmony with these facts, the nasturtium will grow, both in England and the United States, in cooler positions than any other tropical plant, except the potato. The potato, in these respects, sympathizes with our common hardy plants. The damp and hot weather that injures grapes, plums, and gooseberries, by mildew, that rusts wheat, and rots cabbage and turnips, will, at the same time, mildew the potato.

III. THE WEATHER OF 1851.

As the potato disease is ruled by the weather, so it seems in order first to speak of it. The season, as a whole, was wet from frequent and often heavy rains, and a state of things very different from that which existed in other and more remote parts of the country. It was also unusually steady, without those sudden changes and cold chills that characterize our climate in most years. May, and the first half of June, were, as a whole, dark, damp, and cool, and so unfavorable to tropical plants in general, but not so to the potato. The last half of June, and all of July, were hot, damp, and often excessively wet, the showers being intermitted with burning hot sunshine. August was cool, with few warm days -too cool, indeed, for the prosperity of common tropical plants, but favorable to the potato. September was warm to the middle of the month, the only thing which saved the corn crop, which had suffered from the wetness of June and July and the coolness of August.

IV.—DISEASE OF THE POTATO-A GENERAL VIEW.

According to Loudon, it is now one hundred, and according to some other writers it is one hundred and fifty, years since the potato began to be cultivated as a common field crop. In the absence of exact historical

dates, we have no very certain or definite account of potato disease until within the last few years. It has been referred to various causes.

1. Insects, worms, &c.-But unfortunately it happens that, though the potato, like other plants, has its natural enemies, from some of which it has at times suffered considerably, no one class of insects has yet been discovered whose ravages have been of a nature and extent sufficient to produce the disease in the form in which it has appeared. But admit the extent of injury claimed for insects, yet the existing disease is not occasioned by their ravages, because clearly it is occasioned by another cause, adequate to its production, just in this form. And where different varieties have been planted side by side, a portion of the varieties have been diseased, and another portion not. This result has followed regularly year by year—a fact quite inconsistent with the idea that it is occasioned by an insect.

2. Deficient soil.-But the disease often invades new soils of the most faultless character; nay, in this case, as in the preceding, one variety has exhibited disease, and one not, during the same year and in thesame circumstances of culture.

3. Fungus, mould, or mildew.-This theory is doubtless partly true, but not true in the sense in which I have usually understood it to be explained. The mildew, so far from being the originating cause of the disease, is, as I suppose, but the result and proof of pre-existing causes, arising from the action of the weather on the constitutional weakness of the plant.

4. Exhausted energy and consequent exposure is suggested as the true explanation of the disease in every case. This theory exhibits two aspects:

(A.) First aspect of disease. In this case, cold, wet, and windy weather, following that which was hot, dry, and stimulating, seems to paralyze and deprave the circulation of the plant. Thus chemical changes overcome vital energies. Besides this, the action of the wind. lacerates the foliage in many cases. On the return of warm weather, especially if it be sudden, the action of both sun and wind dries up the injured foliage before the exhausted circulation can be restored from the root, which, partaking of the general torpor of the plant, and secluded from the action of the atmosphere by the wetness of the soil, had nearly lost its action. The injury of such a chill is seen to be partly mechanical and partly chemical, and to be closely analogous to that which takes place with all vegetation under the permanent dark and damp chills of autumn. It is also not unlike the injury of hot-bed plants removed too early, and without due preparation. The proofs of such a morbid condition of the potato, thus theoretically stated, will now be exhibited.

(a.) A pallid appearance of the leaves, and often a slightly crumpled state of their edges.-There is a loss of that intense verdure that characterizes the potato in a state of high and healthful growth. The hue becomes yellowish, and sometimes reddish-green. It is such a change, however, as does not strike a careless observer. This change of color is undoubtedly in all cases the first and leading indication of disease, and one that becomes a key to all the rest. It is seen in many cases before the chill passes off, and always within two or three days after. No onecan doubt that this appearance indicates a bad s'ate both of circulation.

and elaboration, on both of which economies not only the health, but the life, also, of a plant depends.

(b.). Wilted leaves and falling flowers.-Speedily after the change of color just noticed, the top or youngest leaf of the plant withers. It is usually but a part of the rosette of leaves that crowns the plant that thus wilts. The flowers, also, whether open or not, fall off without forming any balls. The stems of the flowers break off at the natural joint, a half inch below, through mere starvation

(c.) A blue color on the point and edges of the upper and outer leaves particularly, and a yellow, iron-rust look on the lower and inner leaves.— Can any one doubt that these marks indicate the formation of an acid in the leaf of the potato in cool weather, in June and July, any more than that whole forests of trees should exhibit the same appearances under the permanently damp, cool, and dark weather of September?

These indications follow closely upon the falling flowers and wilted leaf, and progress more or less rapidly, according to the severity of the chill. Sometimes, on any given day, you will find scarcely a discolored leaf; and then in three or four days a whole field will be discolored by them. These indications end in the speedy death of the whole leaf, the whole of the three indications (a b c) acting almost with the speed of frost. At other times these indications are scattering and act slowly. In such a case they soon disappear, and the crop recovers and grows on. In a few cases the vines also speedily die after the fall of the leaves; but more commonly they do not, but struggle a while to live without leaves, and eventually die of starvation.

(d.) Decay of tubers.-If the preceding signs of disease are very violent, the tubers are rarely injured, whether they are one quarter or even three quarters grown. But if its progress is slower and the foliage dies a lingering death, the tubers are sure to be affected by rot.

Just as often as severe chills in the middle of summer occur, so often will many or most of the old varieties exhibit these signs of disease, provided they recovered from the first attack. In reference to the foregoing signs of disease, I now ask, is the disease of the tubers a mystery? And is there any mystery in the exhibition of such signs of disease, coming, as always and only they do, in connexion with a chill?

(B.) Second aspect of disease.-This seems to arise from hot and wet weather, intermitted in many cases with calm, bright, and scalding sunshine. This engorges the plant beyond its powers of healthful elaboration. The constantly wet state of the soil hinders the action of the atmosphere upon it, and so enhances the previous difficulty. The cuticle of the whole plant, the leaf especially, formed amid such circumstancescircumstances akin to the condition of a hot bed plant, with too much heat and water and too little air-the cuticle, I say, thus formed, is necessarily tender. Then the hot sun acting on the plant with its juices thus diseased, and its cuticle thus tender, greatly injures it.

The visible morbid indications arising out of these circumstances are the following:

(a.) A spotted and livid appearance of the leaves, sometimes interspersed with the pale aspect noticed in (A)—(a) above, and giving the leaves of the plant an appearance of irregular patch-work.

(b.) The withered leaf and falling flower also appear, but much less than in the first aspect. The flowers, especially, fall much less speedily

than in that case, and only after being fully and for a considerable timeexpanded. Strong varieties, indeed, in this state of weather, set seedballs freely.

(c.) Steel blue tips on the upper leaves, and iron-rust stains on the inner and lower ones, appear as before, but less frequently.

(d.) Mould or mildew.-This is the one mark of disease, in this second aspect of it, that rivets the attention. It breaks out everywhere upon the plant.

(a.) Upon the leaves, beginning in the dark, livid spots, and spreading, like a contagious cuticular affection upon an animal, until it destroys the whole leaf. This mark is obviously a parasitic fungus, which feeds on the depraved juices of the plant.

(b.) On the stems, especially two or three inches from the upper extremities of the plant. In this case it destroys the whole cuticle, but in moderate cases does not destroy the stem, whose internal circulation yet continues. The stem above this point is as green as before, and frequently is broken partly off by the wind, hangs down, and continues to grow.

(c.) The flower stems also become affected with mildew, frequently, but not always, dying. Often the balls, formed and forming, continue to grow.

(d.) The balls, whether small or full-grown, are seized, if small, with mildew; if full grown, with a brown appearance, which pervades the whole structure, just as in the case of melons, tomatoes, and egg plants, noticed in my former essays on this subject. (See Transactions for 1847, pages 442, 443) Those full grown balls do not usually rot, but continue firm and unnaturally hard. On one of my South American varieties I had nearly one bushel of balls in this condition, amounting to about one fourth of the crop of balls. The balls that set late, on all sorts, after the season of mildew passed away, set and matured without an attack of this sort.

(e.) The tubers, so far as my experience goes in 1850 and 1851, are less likely to be diseased than under the first aspect of disease. Disease also comes upon them, I think; while as yet the mildew has made very little development. Here, as in the first aspect of disease, the strongest varieties suffer least; some of my home seedlings, and most of my foreign sorts, scarcely at all. Here, also, if the first attack is light, the plant recovers and continues to grow, but may, in fitting weather, suffer a second attack. Unfavorable weather may be of that mixed character that the two aspects of disease shall be mingled, more or less. Indeed, they obviously are not very different, each having many of the same indications, and each being the result of severities of weather.

Observations on both aspects of disease.

1. The first aspect of disease alone prevailed previously to 1850; the second has been noticed mainly and almost exclusively in 1850 and 1851. I make this remark with much diffidence. The field is wide and mainly untrodden, and may need renewed observation in coming years.

The preceding description of disease has cost me much time and observation, and is made with the consciousness that I have reported theindications of nature as wisely and truly as I was able.