Fifty years since the peach tree grew vigorously, and almost spontaneously, in many sections of New-England, where the soil and climate were congenial. In more recent times, it has flourished with equal vigor in many parts of the western country, particularly the state of Ohio.

It has required no special powers of observation to discover that it has been gradually progress of this diseased condition has evidently advanced farther in the eastern states, than in the newer and more fertile regions of the west.

A knowledge of the pathology of a disease, whether in the animal or vegetable kingdom, often leads to the discovery of successful means of cure. With this view, attention has been directed to the nature and causes of this disorder. So far as they hare been discovered, they seem to be dependant on the following, "to wit:"

1st. The depredations of the aegeria exitiosa, or Borer. - The first stage of impairment was probably ertablished by the attacks of this insect. It was known as early, or before the commencement of the present century, yet it was then met with only in limited numbers, and its depredations hardly attracted attention. At this time it has become so numerous that every peach tree is annually assailed by from half a dozen to a dozen individuals, in the larvae state.

They perforate the crown of the roots, and excavate it so extensively as to nearly cut off all communication with the body. Before the injury they inflict in one year is corrected by the growth of the ensuing season, a second generation renews the attack. The tree finally sinks under repeated injuries, or perhaps spins out a sickly existence for a few years.

2d. Exhaustion Of The Soil

No species of tree, shrub, or vegetable, can retain health, vigor and productiveness, without a requisite supply of inorganic elements in the soil. Few soils originally contain supplies sufficient to sustain a successive growth of the same species of trees, in the same locality. When a forest is suddenly removed, its place is sure to be occupied by a different growth of timber, and an attempt at cultivating the same kind of crop upon the same field, repeatedly, is sure to be met with manifestations of exhaustion, in the form of disease and unproductiveness.

Such evidences are now too common with the peach tree, when it is planted on soils ex-hausted of the essential elements. The doctrine is not perhaps exploded, that the excretions of vegetables exert an unfavorable influence on a succeeding crop of a similar kind. If it be correct, it may aid in throwing light on the nature and causes of the decay of the peach tree.

3d. The Curl Of The Leaf

Of late years, the first developed leaves in the spring season, become diseased with a spongy and malignant growth, which, in a few days' time, occasions them to fall. This occurs at a period when the vigorous circulation of the sap requires a corresponding action in those important organs. A second growth is soon forced out, which ultimately restores the tree apparently to its wonted health and vigor.

It is, however, evident, that though the recuperative powers of nature may for once, twice, or even thrice, restore a growth of leaves, the shock must at length impair the vitality, and induce an unhealthy condition. This curl of the leaf is produced by the punctures of a small plant louse, perhaps the Aphis persica, or its analogue. It is described by Dr. Harris in his Treatise on Destructive Insects, also in Kollar's work, to which the reader is referred.

People judging of the size of this insect from the extent of its injurious impressions, might overlook it, expecting to find a huge monster where a mite exists, or very likely by searching for it long after its day and generation had passed away.

4th. The. Yellows

It is questionable whether any distinct disease occurs, to which this name is applicable. Perhaps it is only a collection of symptoms arising from causes previously noticed - acting either individually or collectively. Facts seem to favor this view - though the insight of popular opinion is in favor of its being a specific and contagious disease.

In estimating the power and extent of the operation of these causes, it should be recollected that an injurious impression acting constantly upon successive generations, of either animal or vegetable species', may ultimately establish an hereditary entailment, that may be propagated in the form of predispositon to disease, or disease itself. The converse is equally true in producing health or physical development.

These several causes have been exerting their influences on the peach tree for a long term of years - impairing the stamina and health of its fruit germs. These impressions have been propagated and repropagated, in conjunction with the action of the primary causes of impairment, till at length we have only a sickly progeny.

If this view be correct, we have two indications to fulfil in working a cure.

First. To withdraw or counteract the primary causes of impairment.

Second. To propagate only from healthy pits.

Let us begin with perhaps the main cause aegeria or Borer

This depredator can only be assailed with succces by preventing the deposition of the egg into the crown of the root, or by the destruction of the larvae after it has hatched. Embankments of earth, lime, ashes, tobacco, etc, have been tried for these purposes, but with not very perfect success. During a late tour to the eastern states, I had an opportunity of seeing the results of the use of a remedy devised by E. M. Pom-brot, Esq., of Wallingford, Conn. He seems to have found an application which is sure to prevent the perfect insect from laying her eggs in the crown of the roots - the only point at which it can exist and do injury - and is equally certain to destroy the larvae which may have already commenced their career of destruction. The cost and labor of its use are very trifling. Further trials are necessary, to test its certainty. As the discoverer has laid his claims before the Commissioner of Patents, at Washington, I shall say nothing more in regard to it - only expressing the belief that it will prove successful.

The second cause, exhaustion of the soil, must be corrected by the aid of agricultural chemistry. Lime, ashes, bone-dust, salt, barn and poultry manure, etc., empirically applied, will generally correct the evil. No tree pays better for high feeding than the peach, on a silicious soil.

The third cause, the Aphis, seems to be beyond control where it exists in large orchards. It may be destroyed on a few trees by whale-oil soap-suds, and tobacco water.

The fourth cause, the Yellows, I must leave for the investigation and management of those among whom it occurs. Fortunately, little is known of it in Ohio. For the purpose of propagating healthy stocks, pits of the peach should be obtained from sections of the country where this diseased condition does not prevail. J. P. K.

Cleveland, Ohio, Oct. 8, 1851.

Remarks

Professor Kirtland's remarks are closely to the point, and are particularly well timed. We pointed out, five years ago, that the peach tree was becoming enfeebled by bad cultivation, and careless propagation - and the fact cannot be too strongly urged upon nurserymen and orchardists. In fact, the peach has hitherto been cultivated so carelessly, that to an European fruit-grower it would not be called cultivation at all - only a downright abuse of the natural powers of the tree. It is, however, leading to the inevitable result of artificial degeneracy, and henceforth it will require something like attention and care to produce good peaches. Ed.