American Pomology. Apples

"2d. During the months of June and July I collected from time to time very numerous specimens of Black-knot, some of which I cut into to see what larvæ they contained, and some I preserved to see what perfect insects could be bred from them. Besides seven specimens of the common "Curculio," which many persons had previously bred from Black-knot, I bred for the first time therefrom no less than five distinct species of insects, none of which can be considered as gall-makers, but not a single true gall-maker; and I can confirm Dr. Fitch's assertion, that some specimens are wholly free from larvæ of any kind when cut into.

"We will now take up in order the three different theories respecting the nature and origin of Black-knot, which, as already stated, have been maintained by different writers.

"1st. That Black-knot is a mere disease like the cancer.—Dr. Fitch, who maintains this opinion, allows that the black granules found on the Black-knot are a true fungus, 'that the surface of these excrescences, when mature, is always covered with this plant,' and that 'this plant never grows, or at least has never been found, in any other situation.' (Address N.Y. State Ag'l Soc., 1860, p. 21.) * * *

"2d. That Black-knot is a gall.—As already stated, there is no true gall-making insect that inhabits the Black-knot, so far as I can discover on the fullest and most extensive investigation that I have been able to give to the subject. The minute holes commonly found in the old dry Black-knot, which are too large either for the 'Curculio' or for the small moths bred by myself from Black-knot, are of a suitable size for either of the two dipterous' insects which I have enumerated in a note as bred by myself from Black-knot. Consequently the argument which I based upon the existence of these minute holes (Proc. Ent. Soc. Phil. III, p. 614) falls to the ground; and although I found on one occasion the larva of a Gall-gnat embedded in a cell in a Black-knot, yet this was most probably that of the Guest Gall-gnat which I actually bred from Black-knot, as stated in the note, and not of a true gall-making Gall-gnat.

"3d. That Black knot is a fungus.—Just as Dr. Fitch, having proved to his own satisfaction that Black-knot is neither a gall nor a fungus, infers by the method of exhaustion that it must be a disease; so, having proved that it is neither a disease nor a gall, we may infer by the method of exhaustion that it must be a fungus, or rather an assemblage of funguses. In confirmation of this theory may be adduced the very remarkable analogies between the structure of the Black-knot and that of the fungus, described above as occurring on Red Cedar. That this last is really and truly a fungus and not a gall, is shown by the fact, that it is scarcely ever inhabited by insects; for out of hundreds of specimens that I have cut into, both green and dry, not more than two or three contained the larvæ of the moths, but one contained what was probably the larva of an Ichneumon-fly, and all the rest were perfectly solid and unbored. On the other hand, Black-knot is so infested by insects, that it is almost impossible to find a mature specimen that is not all bored up by them. The cause of this remarkable difference may be attributed to the well-known repugnance of almost all kinds of insects for Red Cedar.

"If, then, Black-knot is a fungus, and if, as I think I have shown, it is an annual plant propagating itself by seed or the so-called 'spores,' and the 'spores' make their appearance about the end of July in latitude 41° 30', then it must be obvious that if all the Black-knot on a particular tree is cut off and destroyed in the fore-part of July, or a little earlier or later as you go further south or further north, an effectual stop will be put to its further propagation. It is true that the 'spores' are in the form of an impalpable powder, so that they may be carried some considerable distance from other infected trees by the wind; and it may possibly be further true, that certain 'spores' may lie dormant in the bark for over a year, as the seeds of weeds will often lie dormant in the ground. Still, with all these possible drawbacks, I have little doubt that the above remedy will, as a general rule, if applied according to directions, be found effectual."

The foregoing is interesting as giving the conclusions of an entomologist who had investigated the subject, and arrived at the same result that had been reached by a botanist many years before. Schweinitz, in 1832, published the correct history of the Black-knot in the Transactions of the American Philosophical Society. In the American Agriculturist, April, 1863, p. 113, Mr. C.F. Austin confirmed Schweinitz's observations, and gave a popular account of the botany of this fungus, with figures. It may be considered as fully established that the knot is of vegetable origin; and whenever insects or larvæ are found in it, it is only because they find a diseased portion of the tree suited to their necessities.

Rot and Mildew upon the grape both destroy our crops, and render the vines unhealthy. Would that I were able to give the reader some encouragement as to its cause and prevention, or cure; but some of our oldest and most experienced vine-planters have come to the conclusion, as to treatment, that "the more they find out, the more they don't know." It is now generally conceded that it is caused by a fungus growth. That on the leaves is probably the Oidium Tuckeri, and it is generally supposed that the mildew and rot of the berries is owing to the same cause. The microscope clearly indicates its fungoid character. As to the causes, it must be admitted that the weather favors or prevents its access, and that so far it is a proximate cause, but that the spores are the true origin of the trouble. The Cincinnati Horticultural Society, whose members have long had opportunities of studying this malady, have come to the following conclusions, which, it will be seen, are not very satisfactory.

To the Cincinnati Horticultural Society:—We have been appointed by you to discharge a certain function. Having examined the premises and considered the subject, we do now report: That, notwithstanding the discouragements attendant upon the experience of most vine-dressers during the past season, we are determined to persevere in viticulture, for the following among other reasons:

We have our capital invested in a way which has been profitable, and we believe will be so again.

Our lands are occupied with a growth that has required time and labor to produce, and which we are unwilling to sacrifice.

We do not believe that the diseases to which the vines and fruit have been subjected, are dependent upon long pruning or short pruning, upon deep culture or shallow, nor any of the causes to which it has been attributed, that are under the immediate control of man, but that the cause is CLIMATIC.

We do not believe that the rot and mildew can be warded off by leaving the wood upon the vines, nor that the usual vineyard method called short pruning, will render our vineyards more subject to this disease.

We do believe, however, that we have yet much to learn in regard to the philosophy of pruning which it were well for us to study, and that by so doing we may gather some useful hints in relation to this very important part of a vine-grower's duties.

We do believe, as a result of our observations, that some varieties of grapes are more healthy and vigorous than others; and, on the other hand, that some are peculiarly subject to the inroads of these maladies which have so terribly affected the fruit, the foliage, and the green wood of our vines. We do firmly believe, that our societies should avoid recommending the extensive planting of any trees or vines that have not proved themselves general healthy, and free from the maladies in question, for a number of years, after trial in different situations.

We do believe that systematic efforts should be made with different remedial and preventive agents, to avert the disasters that have overtaken our vine-crops of late years, and, with this view, as we have reason to believe that the difficulty depends upon the existence of some epiphytic plant, and as we are informed that sulphur and sulphate of iron exert an obnoxious influence upon the whole class of fungi, we recommend our brother vine-dressers to take courage, and to make vigorous and systematic efforts to ward off the difficulty the coming season, by the regular and persevering applications of these substances to their grape vines.

For your encouragement, we will also refer you to the history of the vineyards of Europe, which have suffered in like manner, and which have at length recuperated their energies and become productive. Why may not the same good fortune await us?

Very respectfully submitted, byR. Buchanan, Chairman.

CHAPTER VI

THE SITE FOR AN ORCHARD

A MATTER OF IMPORTANCE, NOT OF MERE CONVENIENCE—LOW VALLEYS LEAST DESIRABLE—BASINS, EVEN IF ELEVATED, SUBJECT TO FROSTS—LOCAL DIFFERENCES OF TEMPERATURE, OFTEN FATAL TO TENDER VEGETATION—THE FROST LINE NOT DEPENDENT UPON MERE ELEVATION, BUT UPON RELATIVE ALTITUDE—MODERATE BLUFFS BESIDE VALLEYS, OR RIDGES IN A PRAIRIE, ARE BETTER THAN HIGH VALLEYS AMONG MOUNTAINS—DRIFT FORMATIONS, PRESENT INEQUALITIES OF SURFACE—FAVORABLE INFLUENCE OF THE WATER OF RIVERS AND LAKES UPON THE CLIMATE—INSULAR POSITIONS AND LACUSTRINE SITUATIONS HAVE A PECULIAR CLIMATE—FOGS—LATENT HEAT BECOMING SENSIBLE—METEOROLOGY WILL FURNISH AID TO THE ORCHARDIST—COLD STORMSAspect—PROTECTION FROM WINDS, ESPECIALLY A PRAIRIE QUESTION—EFFECTS OF AGITATION IN THE ATMOSPHERE—BELTS AND SCREENS OF TIMBER DESIRABLE—WINTER KILLING OFTEN DEPENDENT UPON THE CONDITIONS OF THE TREE—VARIETIES MOST SUBJECT TO THIS—LISTS—SOILS, PERMEABLE AND TENACIOUS—ADAPTATION OF SORTS TO SOILS—GEOLOGICAL FORMATIONS TO BE OBSERVED IN MAKING SELECTIONS.

Site.—The selection of a suitable site for an orchard is a matter of no small moment to him who would be a successful grower of fine fruits. Without, at this time, pausing to inquire into the characters of the soil, let us examine more particularly the aspect of the field to be appropriated to this important crop; for the orchard is a permanent investment, and so much depends upon the site, that we should make some sacrifice of our convenience, rather than commit any error in this particular. In the first place, then, let it be understood that the orchard should be well exposed to the sun and air. The least desirable positions for orchard planting are narrow valleys, particularly limestone valleys in a mountainous country, traversed by a small brook, or where the surface is spouty from springs or subjacent water. Even if such depressions are considerably elevated, but surrounded by higher and abrupt elevations, they will be found obnoxious to late and early frosts in spring and fall, especially the former, which are often disastrous in such situations, after the fruit-buds have expanded in these sheltered nooks. Every one at all conversant with meteorological observations made in a broken country, is aware of the different range of temperature that will be indicated by instruments suspended at different elevations.18 When the cooling influence of radiation has lowered the temperature of the surface of the earth and of objects near it, the stratum of air in immediate contact will be chilled, and growing heavier, will flow down into the most depressed situations, and, accumulating there, will cause a difference of several degrees of temperature. This, when near the freezing point, will be of the greatest consequence to tender vegetation, which may be preserved in perfect safety at forty degrees, but will be destroyed at thirty degrees, or even at a higher point, in some cases.

The frost line becomes a very important subject of inquiry in the selection of an orchard site, and in some countries we find that its position may be definitely settled within a limited range of elevation; not that a certain level can be indicated, above which there will always be an immunity from frost, while all below will suffer, but we may approximate, in certain situations, so nearly as to indicate that certain sites are safe or unsafe.

Nor is it the absolute elevation alone that is to be taken into the account; in any given locality, we may assume that the higher the orchard is situated above the water levels, the safer it will be, and that the lowest depressions are the most unsafe or frosty. It is not always the mere elevation, but rather the relative elevation of the site, that renders it more desirable than another in the same region. There are many orchards that are situated upon a moderate bluff, with a rapid descent of only a few feet or yards, into a swale or valley of moderate extent; these we find to be uninjured, when another at a greater elevation, but in a depressed basin surrounded by higher lands, will be found to have suffered from the influence of frost. In the one case, the cold air could flow off rapidly into the adjoining depression, while in the other, the cold air from adjoining slopes would collect, and accumulate in the situations described.

In the great plateaus of the world, we often find immense tracts of land so nearly of the same level as scarcely to afford sufficient drainage for the surplus water; of course, we should expect to find, in such places, little variation of temperature arising from difference in elevation. But even in such situations, whether we examine the table-lands of our timbered regions, or the extended areas of the prairie country, we shall find that the drift formation which covers these vast tracts, has not been distributed evenly, but that there are successive rolls or swells frequently recurring, which give, in some instances, considerable variations of level. A bold ridge, of fifty feet or more in hight, rises abruptly from the level prairie, stretching along for miles, and affording admirable exposures for orchard sites. Such places are observed to be free from late and early frosts. In other places, there is an abrupt depression of the surface, answering the same purpose—drawing off the cold air. These may be very moderate in their extent, as the prairie sloughs, or they may be small vales, the courses of the minor streams, or of larger extent, the valleys of rivers, or the depressions of lakes. In these latter cases, the modifying influences of considerable bodies of water enter into the frost problem as an element of no mean value.

It may be asked: How do these masses of water affect the frost? Science answers: By their evaporated moisture influencing the atmosphere. This may save us from the blighting influence of frost, by enveloping the frozen vegetation in a wet blanket of fog; enabling it to be thawed in the dark, as it were, by which we avoid the influence of a bright sunshine, that would have destroyed the tissues had they been suddenly exposed to it when frozen. An equally important result is derived from the direct influence of the humidity of the atmosphere, which modifies the temperature remarkably, as in the immediate vicinity of large bodies of water. Insular situations especially, even when low, are known to have a more genial climate in consequence of this condition of the atmosphere, which depends upon the large amount of caloric that is present in the latent form, in the vapor, and which becomes sensible heat as fast as the moisture is condensed; as well as by the sensible caloric, the absolute warmth of the water, affecting the temperature of the atmosphere.

We thus see that very opposite situations, in regard to mere elevation, may both be recommended for orchards; but the latter are the exceptions rather than the rule, for we can not always count upon the saving influence of a fog, nor are the modifying effects of a moderate sheet of water always to be depended upon at the time when most needed. Still, we may find a few favored spots, where an insular position, in a lacustrine situation, receives a double influence—acting at both extremities of the season of vegetation, in quite an opposite way, but in both acting favorably. In such places we shall discover that the spring opens late, being retarded by the cold atmosphere flowing over the chilled waters, that may be even icy, when inland places in the same latitude are rejoicing in a mild and genial temperature, tempting the expansion of the flower-buds. Vegetation on an island thus situated is retarded until all danger of frost has passed, and the air has received the full benefit of warmth from the water. Then, again, in the autumn, when we are in danger from the access of an early frost, such as sometimes, north of latitude forty degrees, destroys the whole crop of corn, almost universally, over hundreds of miles, these favored spots have really a warmer atmosphere, from the influence of a great extent of water, that has enjoyed a summer's sunshine, and which warms the air by giving off its heat very steadily, but slowly; and besides, as the surface of the land cools by radiation and condenses the watery vapor, it receives accessions of temperature that had been locked up, or was insensible in the vapor. Hence we find that in these places, though the opening of spring was retarded a month, the approach of winter and autumnal frosts is warded off for two months, making the season really one month longer than in the same latitude inland.

It must be confessed, however, that the subject of meteorology is not fully understood. We have but a glimmering of the light that we hope is to be shed upon the subject when the deductions from millions of observations, long continued and systematically conducted, shall have been wrought out for the benefit of the orchardist and the general agriculturist.

We also have storms accompanied by a low temperature, passing across the country, in which, at times, the greatest intensity of cold is at the southern border. Such a one passed from the west to the east in January, 1852, in which the mercury, near Marietta, O., sank to thirty degrees below zero; at Zanesville, O., on the same river, it was twenty-seven degrees; at Lancaster, O., thirty-two degrees; while at Cleveland, O., it was only fifteen degrees below, and at Aurora, on Cayuga Lake, N.Y., influenced by the unfrozen water, its greatest depression was only four degrees below zero.19

Aspect.—When considering the orchard site, the best aspect of the ground becomes a matter of interesting inquiry. To all vegetation, the morning sun is a welcome visitant after the night's repose; for plants, as well as animals, rest from their functions at night, and all nature rejoices in the return of day; hence an eastern or a southeastern exposure is generally preferred, but we find that practically there is little difference in the different parts of an orchard that can be fairly referred to this cause. Some planters prefer a southern slope, thinking that the fullest exposure to the sun is essential; others select a northern aspect, in the hope that they may there avoid a too early excitation of vegetable life, and also that the heats of summer may be thus moderated. In my own opinion, the aspect is a matter of little consequence to the success of an orchard, though my predilections are in favor of an easterly exposure. The danger of a southern aspect in summer, and the advantages of the northern slope, may, in a great degree, be obtained or obviated by judicious planting and pruning, as will be set forth in another place.

A theory has been started by those who are opposed to a northerly slope, that vegetation continues later in the season in such situations, especially with young trees, and that hence they are not in so good a condition to resist the access of very severe weather at the sudden setting in of winter. The hypothesis is not sustained by long-continued observation, although many facts noted in the autumn and winter of 1859 induced persons to embrace the theory; these were particularly the killing of the peach-buds, upon northern slopes, by the December frosts. There is no evidence that there was any want of perfect ripening of the wood in these situations; on the contrary, it is well known that, long before December, the growth of these very trees had been checked, the wood had been well ripened, and the foliage had been cast to the ground.

The warmer exposure of a southern slope may, and often does, favor the premature swelling of the buds and starting of the sap during mild, pleasant, and bright weather in the winter, and vegetation is often seriously injured from this cause.

In many parts of the country, it is much more important to consider the exposure to the prevailing winds of the region, and to select the site and aspect that shall enjoy the benefit of protection. This, I am aware, is a proposition that has had opponents; as well as advocates, in the broad savannas of the West, where, especially, it becomes a question of the greatest importance. There are benefits as well as evils attendant upon the motions of the atmosphere. The swaying of the limbs, when agitated by the breeze, gives them tone and strength, and may assist in the circulation of the sap within their cells; and the constant agitation of the atmosphere, commingling the warmer with the colder portions, will often modify the temperature to such an extent as to give an immunity from the frost in the open prairie, at the same moment that the more tranquil air, within a limited clearing of forest lands, has been cooled down, by radiation, to the frost point. On every account, therefore, the moderate and reasonable exposure to the influences of a mobile atmosphere is rather to be courted than shunned.

The views that have been advanced by the advocates of protection for orchards on the prairies, have been somewhat modified since they were first promulgated. We are now told, by those who have opposed "protection," that narrow timber-belts of evergreens and deciduous trees, should be planted on the windward sides of orchards, to moderate, not to cut off, the aerial currents; in this all will agree, and those who have any sympathy for a tree will surely prefer to have the blasts, that sweep over miles of open country, somewhat checked and tempered before reaching either themselves or their orchards. The testimony as to the effects of cold in sheltered and in exposed situations, it must be confessed, appears somewhat contradictory; but this is because we have not all the elements of a complex problem.

Winter-killing.—A most serious evil, both to the nurseryman and orchardist, is the severe injury sometimes done to the trees by frost. This is commonly known by the term "winter-killing," which has, at times, destroyed millions of trees, and thus blighted the hopes of long-continued labor and large investments of capital. Some orchardists have been disheartened, and have given up in despair. The investigation of the causes of this disaster, and the conditions under which it occurs, will be of great value to future planters; and though, perhaps, we have not yet at command sufficient data for the full explanation of the phenomenon, it may be well to look into the attendant circumstances that have been observed; and as some of the most important considerations depend upon the soil and exposure, they may be well introduced in this place.

I have already alluded to the theory, that the north hillsides maintain a later growth than other situations, and have stated that the facts do not sustain the position. The warm exposures on southern slopes and sheltered nooks, are apt to favor the premature starting of the sap in the mild weather that often occurs during the winter, in our changeable climate. On the prairies, and on flat lands elsewhere, an excess of humidity in the soil will contribute to this disaster; and in such situations we may often observe the most terrible destruction following a great and sudden change of temperature. Exposure to long-continued cold, with severe winds, seems to dry up the juices of the plants, in some instances, and thus effect their destruction. This, in the far North, is believed to be a frequent cause of the evil. The condition of the tree upon the access of severe cold is too important a subject to be lost sight of, and has already been alluded to.

Of any given variety, the more perfectly dormant the plant, and the more complete its condition of hybernation, the greater will be its immunity from this evil. The atmospheric changes and conditions we can not control, and we can modify them only in a very limited degree, by hedges, by timber-belts, and by evergreen screens, the value of which begins to be appreciated. The state of the soil, as to its moisture, is under our control, and by thorough and surface-drainage, we may obviate one very important condition that conduces largely to the injury under consideration—the excess of moisture in and upon the soil.