There is the more necessity for doing this II. THE TWOFOLD SYMPATHY OF THE POsince the disease has assumed a form some- TATO.-1, As a simply tropical plant, it rewhat new in my experience, though I sup-quires like most of its class, steady and unipose not new in other parts of the country, form weather, but less heat than most of its where the climate has been somewhat dif- associates. It fears not only frost, but all ferent. This new phase of disease is its sudden and extreme changes. From such obvious connection with hot and wet weather, changes, I think, most of the disease occurinstead of that which was cold, wet and windy, ring in my experience before 1850 arose. alternating with that which was hot and dry. 2, As a mountain tropical plant, it will not This phase of disease was alluded to theo- only bear, but requires, for its best development, retically in the Transactions for 1847, pp. more air, moisture and coolness, than most 444 and 445, and in those of 1848, pp. 423 other tropical plants. The nasturtium, howand 424. But it could not there be prac- ever, is found growing on the mountains of tically described, as it is in this paper, since South America, in company with the potato, at that time it had not been practically ex- beyond the limits of all other cultivation. perienced. 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 that rots cabbage and turrips, will, at the same time, mildew the potato. 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 Bogota, a city of New Grenada, situate upon the mountains, 8,500 feet above the sea, 5o 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 50 in any one day. There he found, as Humboldt had more than forty years before, potatos 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 side 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 season. Nothing but the greatest constitutional vigor could ever here have sustained the potato in a prosperous growth, in the same soil and climate that produces melons, tomatos, corn, egg plants, etc. 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. 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 CULTURE OF THE POTATO. 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 : 243 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 hotbed plants removed too early and without due 1st. Insects, worms, etc.-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 preparation. The proofs of such a morbid been of a nature and extent sufficient to condition of the potato, thus theoretically produce the disease in the form in which it stated, will now be exhibited. 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. 2d. 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 the same circumstances of culture. 3d. Fungus, mold 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. 4th. Exhausted energy and consequent ory exhibits two aspects: 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 one can doubt that this appearance indicates a bad state both of circulation and elaboration, on both of which economies the health not only, 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 fall ing 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 also appear, but much less than in the first field will be discolored by them. These aspect. The flowers, especially, fall much indications end in the speedy death of the less speedily than in that case, and only whole leaf, the whole of the three indica- after being fully and for a considerable time tions (a, b, c,) acting almost with the speed expanded. Strong varieties indeed, in this of frost. At other times these indications state of weather, set seed balls freely. 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 awhile 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 onequarter 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. 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. Mold 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: 1, 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. 2, On the stems, especially two or three inches from the upper extremities of Just as often as severe chills in the mid- the plant. In this case it destroys the whole dle of summer occur, so often will many or cuticle, but in moderate cases does not demost of the old varieties exhibit these signs stroy the stem, whose internal circulation of disease, provided they recovered from yet continues. The stem above this point the first attack. In reference to the fore- is as green as before, and frequently is going 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 connection with a chill. broken partly off by the wind, hangs down and continues to grow. 3, The flower stems also become affected with mildew, frequently, but not always dying. Often the balls, formed and forming, continue to grow. 4, Second Aspect of Disease. This seems to The balls, whether small or full grown, are arise from hot and wet weather, intermitted, seized, if small, with mildew, if full grown, in many cases, with calm, bright and scald- with a brown appearance which pervades ing sunshine. This engorges the plant be- the whole structure, just as in the case of yond its powers of healthful elaboration. melons, tomatos and egg plants noticed in The constantly wet state of the soil hinders my former essays on this subject, (see the action of the atmosphere upon it, and Transactions for 1847, p. 442, 443.) Those so enhances the previous difficulty. The full grown balls do not usually rot, but concuticle of the whole plant, the leaf espe- tinue firm and unnaturally hard. On one cially, formed amid such circumstances of my South American varieties I had nearly circumstances akin to the condition of a hot-one bushel of balls in this condition, amountbed 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 above,) and giving the leaves of the plant an appearance of irregular patch work. b. The withered leaf and falling flower, ing 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 con- hot. Plums are rotting badly. Goosebertinues to grow, but may, in fitting weather, ries and peaches are scalding on the sun suffer a second attack. Unfavorable weather side. 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 the indications of nature as wisely and truly as I was able. July 3d. Most ordinary varieties are now dropping their flowers, whether open or not. Potato disease reported at Portsmouth. July 7th.-Weather still damp and hot. Some foreign sorts, received this year, are setting balls very freely. July 23d.-Color of foliage has long been bad. It now exhibits a pale sickly green, intermingled with dark livid spots. Blue tips are now abundant on feeble sorts. Saw Saw the first mildew today. It occurred on varieties from the western part of the state, in a position where they were planted rather closely and grew luxuriantly. many mildewed leaves in the field of a neighbor. This exhibition of mildew is four weeks later than last year, exactly in harmony with the relative commencement of hot and wet weather, which began in 1850, 2. The months of June and July, particu- July 14th, in 1851, June 14th. Diseased larly from the 25th of June to the 20th of potatos first seen in the Utica market today. July, is the season when the potato is most July 23d to 30th.--Balls 'setting quite likely to be diseased. That is the season freely on some foreign sorts, on the seedwhen the changes of weather are most sud-lings derived from them, and on some of den, and when the potato exhibits the larg- my home seedlings. est quantity of foliage, and in the most tender and susceptible condition. Those who judge of potato disease mostly from the indications on the tuber, will not ordinarily find it until a much later period. 3. These two aspects of disease are seen to be in exact sympathy with the twofold sympathy of the potato. (See above in No. II.) The first aspect of disease is suffered in common with most other tropicals cultivated in this climate. This point is fully illustrated in the Transactions for 1847, pp. 442-444, and for 1848, pp. 411-414. So the second aspect of disease is suffered in common with many hardy plants and fru ts, such as plums, gooseberries, walnuts, apples, etc., and some vegetables, as carrots, turnips and cabbage. V. ACTUAL OCCURRENCE OF DISEASE IN 1851. June 28th. Potatos have now been up about one month. Noticed today withered leaves and falling flowers, on some sorts got from Buffalo, and others from near New York city, and also in the old early pink-eye. June 30th.-Saw a few steel-blue tips on the leaves of some of the weaker sorts. The weather for two weeks has been damp and July 25th.-Hot, wet weather. Potatos closely planted and falling down badly, present many yellow leaves, dying and dead in the center of the plant. July 26th.--Found one diseased tuber. Potato disease reported in Ireland. July 28th.--Hot and wet weather, with severe, scorching sunshine. The aspect of the foliage very bad. Mildew, first seen on the 23d, is now everywhere apparent on all the old varieties, and usually in proportion as they are close planted and have grown luxuriantly. These indications are scarcely seen in my best foreign sorts and home seedlings. July 29th.-Noticed that, in extreme cases, the mildew extends to every part of the plant, stems, leaves, flowers and balls. Considering the engorged state of the plant, after three weeks of continuous hot, wet weather, intermingled with hot, burning sunshine, one can not but fear the worst consequences to the potato crop. The progress of the mil lew is very rapid. July 31st. Three days of cooler weather, without rain, produces a little check to the progress of mildew. The diseased leaves 2. I have seen no single hill of potatos are sloughing off, while its progress is often arrested on a single leaf, the diseased part this year, entirely exempt from mildew ; falling off, and the remainder continuing although I had many on which a careless green. The dryer and cooler state of the and ignorant observer would have noticed atmosphere seems to have strengthened the no signs of disease. cuticle, and allowed the engorged juices to dissipate, thus removing the cause of mildew. August being mostly a cool, dry month, was favorable to the health of the potato, especially as a means of checking the progress of mildew. August 13th. The foliage of my ordinary field crops is nearly all brown. The cool weather of the last two weeks has undoubtedly saved the potato crop in central New York. Indeed, I think that one week's continuance of such weather as had for some time been in existence previously to July 27th, would have destroyed all common varieties of potatos, root and branch. August 15th to 19th.-Seed balls are setting very freely. Many sorts, as the yam potato, and some both of my home and foreign seedlings, that had refused to set during the continuance of the mildew, are now setting freely. As most of these varieties had manifested great permanence of flowers, the failure to set fruit, undoubtedly arose from want of sufficient dryness in the air, for the delicate operation of fructification. That this failure to set seed balls did not arise from weakness, is evident from another most remarkable fact. The flower stems, even the small ones that had shed single flowers, subsequently turned to leaf-stems, and grew in some instances from six to ten inches in length; and where this was not the case, they became covered with leaves; these leaves and stems were doubtless the result of those juices originally elaborated for the support of the seed balls, which failed of setting. In the case of old and feeble varieties, the flowers usually fell while yet in the bud, and the very stems on which they grew, often withered from weakness, or were dwarfed. VI. RESULTS OF THE SEASON.-1. My foreign sorts generally, except some imported this year, in a shriveled and feeble state, have substantially resisted the mildew, and even in this excepted case, they recovered, set more fruit, and were eventually killed by the frost. My seedlings, also, both home and foreign, were generally but little injured. 3. The seed balls of this year have, in many cases been very large, in one case, the larger balls weighing one-half ounce each. 4. Fruit generally has been injured.— Plums, on my sandy soil, have been a failing crop, though setting abundantly, and also protected from the curculio. They rotted when two-thirds grown, partly after and partly before the untimely fall of the leaf. The Elfrey, Damson, Prince's Imperial Gage, and the Yellow Gage, all did tolerably well, and in the order here indicated, but most other sorts failed almost entirely. My neighbors, who had plums on heavy clay soil, were much more successful. Grapes failed exactly as plums did.* Gooseberries and peaches were both injured by a sun scald on the sun side of the fruit. Apples.-Many varieties were spotted and dwarfed, worse than I ever knew the same sorts to be before. Others were not sound, and showed a disposition to rot, as I have never known the same sorts to do before. Walnuts, both shag-bark and black, were very poor, the meat being either shriveled or bad in flavor. 5. Tropical plants were injured the first half of June by the coolness of the weather. During the long season of mildew they suffered, not however I think from that cause, but from profuse rain. The ripening fruit was injured in August by the general coolness of the weather. 6. From all the foregoing considerations combined, I conclude that the weather of 1851 was peculiarly unfavorable to the health of the potato, and would have been so had it occurred fifty years ago. The timely cool, dry weather of August saved the crop from much rot, but as the vines were already dying, the crop has been light from the smallness of the tuber. The foli No one who watched the progress and appearance of mildew on the wood and leaf of the grape can doubt that its cause was one with the potato disease The natural hardness and the brown tinge of the berry of the grape, without and within corresponded exactly moreover with the similar appearance of the potato ball this year, and with that of diseased melons and tomatos in former years. |