2. The months of June and July, particularly from the 25th of June to the 20th of July, is the season when the potato is most likely to be diseased. That is the season when the changes of weather are most sudden, and when the potato exhibits the largest quantity of foliage, and in the most tender and susceptible condition. Those who judge of the 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 two-fold sympathy of the potato. (See p. 355, 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, pages 442-444, and for 1848, pages 411-414. So the second aspect of disease is suffered in common with many hardy plants and fruits-such as plums, gooseberries, walnuts, apples, &c., and some vegetables as carrots, turnips, and cabbage.

V. ACTUAL OCCURRENCE OF DISEASE IN 1851.

June 28.-Potatoes have now been up about one month. Noticed to-day 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 30.-Saw a few steel-blue tips on the leaves of some of the weaker sorts. The weather, for two weeks, has been damp and hot. Plums are rotting badly. Gooseberries and peaches are scalding on the sun-side.

July 3.-Most ordinary varieties are now dropping their flowers, whether open or not. Potato disease reported at Portsmouth.

July 7.-Weather still damp and hot. Some foreign sorts, received this year, are setting new balls very freely.

July 23.-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 the first mildew to-day. It occurred on varieties from the western part of the State, in a position where they were planted rather closely and grew luxuriantly. Saw 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, July 14; in 1851, June 14. Diseased potatoes first seen in the Utica market to-day.

July 23 to 30.-Balls setting quite freely on some foreign sorts, on the seedlings derived from them, and on some of my home seedlings. July 25.-Hot, wet weather. Potatoes closely planted and falling down badly; present many yellow leaves, dying and dead, in the centre of the plant.

July 26.-Found one diseased tuber. Potato disease reported in Ireland.

July 28.-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 homeseedlings.

July 29.-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 cannot but fear the worst consequences to the potato crop. The progress of the mildew is very rapid.

July 31.-Three days of cooler weather, without rain, produces a little check to the progress of mildew. The diseased leaves are sloughing off, while its progress is often arrested on a single leaf, the diseased part falling off, and the remainder continuing green. The drier and cooler state of the atmosphere seems to have strengthened the 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 13.-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 27, would have destroyed all common varieties of potatoes, root and branch.

August 15 to 19.-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 froin 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 shrivelled 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.

2. I have seen no single hill of potatoes this year entirely exempt from mildew, although I had many on which a careless and ignorant observer would have noticed no signs of disease.

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. Applesmany 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 barks and black, were very poor, the meat being either shrivelled 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 foliage of the crop in Oneida county was generally all dead by the middle of August.

7. In parts of our country where the season was dry and hot, or dry and cool, the preceding suffering of the potato crop was not, of course, felt, and will scarcely be appreciated.

APPENDIX TO ARTICLES ON POTATO DISEASE IN 1851.

MISCELLANEOUS FACTS AND OBSERVATIONS.

1. Culture of Potatoes in the Southern States." In Mississippi and parts adjacent, the best common potatoes that we have ever seen were planted in November and December. Plough the ground deep-not less than ten inches-twenty would be better-open a deep furrow and fill it with good stable manure, well trampled down; cover it slightly with earth and lay the tubers on ten or twelve inches apart; then cover with a heavy furrow turned up from each side and smoothed down with a hoe. Average the furrow so that the water will not stand, and you will have a good crop."-American Agriculturist, December, 1847.

The noticeable points here are the earliness and depth of planting. These points have both been urged in the preceding essays. They give deep and wide-spread space to the root, and thus secure the plant from drought, heat, and sudden changes, while the crop is matured before the

*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 unnatural 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 tomatoes in former years.

highest heats and drought of summer. The usage of the South is based on the implication that the potato requires cool and moist culture.

2. Culture of the potato in cold and wet weather in France.-In the northeast part of France lies the district called Ban de la Roche. It was the residence of the celebrated Oberlin. In the life of that excellent man, (Philadelphia edition, 1830, page 84,) we have the following record: "By his extraordinary efforts and unabated exertions he averted from his parishioners, in 1812, 1816, and 1817, the horrors of approaching famine. The new crop of potatoes that Oberlin had lately introduced formed the principal subsistence of the people during those disastrous years, when the season was so rainy and cold that they could not get in two-thirds of the grain at all."

The single point which I wish to notice here is the fact that, in a cold and wet season, when grain could not be obtained for food, the potato was productive, and became the chief reliance of the people. The climate of the northeast of France is much cooler than that of New York and New England, and much less exposed to severe and sudden changes. Here is proof that the moist and cool soils-such as are usually found in mountainous districts-are congenial to the potato. The last two years noticed above will be well remembered as having been years of scarcity and suffering in our own country. During one of them, (1816, I think,) we suffered at least a slight frost in every month of the year. The potatoes were excellent, and the grass, though short, made very rich hay. Rye was sold at $2 per bushel, and other grain correspondingly high that year.

3. The potato not an acclimated plant.-The impression is widespread that tender tropical plants can be gradually carried northward, and hardened to the climate until they will bear frost, and flourish there as well as in their native clime. The whole impression is erroneous. Tropical plants may shorten the period of their maturity, and a few probably may be budded or grafted on hardy northern varieties that are nearly related, and thus a little strengthened. But this is the utmost that can be done. The fact that our summers are, while they last, nearly as hot as tropical ones, is the only reason why we can cultivate such plants as corn, cucumbers, melons, pumpkins, squashes, tomatoes, &c. But no one of these bears frost now, or matures good fruit in a short, cool, or wet season, any better than the first year they were introduced. Nay, some species of southern plants, when first introduced, possess a vigor which they afterwards lose.

My Bogotá potatoes, imported in 1848, bear the high dry heats, the wet chills, the lacerating winds, and the sudden changes of this climate, better than any of our old varieties. But they require a long season to mature their tubers, and four years of cultivation have done nothing, or at least little, to shorten it. Nothing, I think, but reproduction from the seed ball will shorten them, or any plant similarly situated. One reproduction has already shortened the period of maturity in this variety, but not sufficiently. A second reproduction will, I hope, shorten them to the requirements of our climate. As the potato is a mountainous plant, cultivated over a wide extent of latitude, so it is possible, among numerous importations, to find some whose period of maturity will be found exactly fitted to our own climate. So it has been in my experience. 4. The curled leaf.-This seems to be a constitutional defect that be

longs mainly, if not exclusively, in my experience, to the red varieties. The old red, one of our strongest and best old sorts, has it. My large family of home seedlings, derived from it, show it in some of the varieties, even where that variety is much stronger than the parent. So, also, two varieties of reds, sent me from abroad, exhibit it, although the seed was plump and fresh. I have not examined it further than to notice that it comes on early in the season, and hopelessly dwarfs it, but does not disease the tubers.

5. The relation between bearing seed balls and the health and vigor of varieties. The following thoughts are suggested with great diffidence, though strongly confirmed by the experience of past years. The general impression is that seed ball bearing is a test of hardiness among varieties of potatoes. I think the doctrine in general is true, but it has many exceptions and qualifications. The capacity of a plant or tree to bear fruit seems often to depend not entirely on the general vigor of the plant or tree, but also upon the particular character of the flower or of the season. The tree may possess most unquestionable vigor, while the flower may habitually be deficient either in some indispensable organ, or in the vigor of that organ. Those acquainted with the controversy about pistulate and staminate strawberries will understand me. A wet, cold, and windy season at the time plants are in flower, frequently prevents their fructification. Some varieties of pears and plums, as well as of melons and cucumbers, frequently thus suffer. When once a plant or tree has established a character for regular fruit-bearing, and subsequently, and almost habitually, fails to do so, there is undoubted evidence of depreciated energy. The following facts on this subject are clearly ascertained in my experience in regard to the potato:

(1.) All our old varieties in these days of disease drop their flowers without setting fruit. The exceptions are so few as not to be worth naming. The flowers frequently fall when in mere bud, and long before they expand.

(2.) We formerly had a very good potato which bore no flower, and was called the "no-blow."

(3.) The yam potato has exhibited, in the cultivation of 1851, a good degree of vigor, much more than any of the old sorts. Its numerous large white flowers exhibited a marked permanence, but not one of them set for fruit during the prevalence of mildew in the month of July. In August, under cooler and drier weather, they set and matured a moderate quantity of balls. Here I think the fault was in the character (I will not say weakness) of the flower itself, or possibly the weather was too damp for fructification.

(4.) Some foreign sorts, whose tubers were imported in an exhausted state last April, and became liable to mildew in July, set balls earlier than any others, and in amount beyond anything I ever witnessed. They set them before the occurrence of mildew, while it continued, and after it passed away. The tubers in this case were very small.

(5.) Other sorts, both home and foreign, set fruit moderately, both during and after mildew.

(6.) A variety of home seedlings, which I deem stronger than any other, bore but 3 balls in 25 hills, although the foliage had an unusually upright growth, with numerous flowers.

(7.) Another home seedling, of the same family, and growing near