The principal horticultural event worthy of notice last season, in these parts, was the great and unparalleled blight and failure of all sorts of fruit.

The spring frosts killed the plums, peaches, and apples, and as there was no food for the Curculio and kindred vermin last season, we may expect that a great variety of specific preventives for their ravages, will succeed to perfection - for an enemy already starved and annihilated is often easily conquered.

We will therefore leave these specifics and all further experiments, and eat our plums till the "Grand Turk" has time to multiply or emigrate for another crusade upon us - and also learn that Providence is wise - and that frosts that kill all the fruit, are some* times most excellent and necessary things; worth more for the " Turk" than worlds of pigs, chickens, sulphur, salt, etc. etc. Both the blight and grape rot are different matters, from which as yet we see no relief.

The season till September was remarkably wet, and all the grapes were smitten with the rot sometime in July - it was an entire destruction, and no remedy seemed to do the least good - while the true philosophy of the matter seems to be more of a mystery than ever. No positioner training, or pruning, or picking, or artificial soil, or subsoil, or drainage, seemed to be of the least avail - while some facts seem strongly to indicate that the real cause must be either fungus or animalcule.

' I shall, this spring, enter upon a new course of experiments as regards the grape rot, by planting vines in brick and cemented vine pits or vats, filled with different artificial soils and subsoils, of which in due time you shall hear. My Catawba vine was the only one that escaped a total rotting and loss of fruit for two past years.

As to the pear and apple and quince blight, it swept every thing last season in these parts. It entirely destroyed every privet bush and hedge on my grounds, and attacked the pears and quinces with unparalleled vehemence. The apple trees seem to have an innate power of resistance, (or a vix medicatrix,) which the pears, quinces, and privets have not.

I devoted much time to the phenomena, and examined carefully all the pear trees in town, and I think the following facts quite well established with us:

I. There are some six forms of blight, not one alone, if we may believe what appears to be well authenticated by credible witnesses, and they all appeared among us the last season:

1. There is an insect which eats into the terminal bud, and down the pith to a considerable distance, and causes a terminal blight in the apple tree. This is not serious, and has been found on no other tree here.

2. There is a sort of locust that stings the branch, and causes a similar phenomenon sometimes.

3. There is an insect that eats into the roots of any of the tender buds on the terminal branches, and sometimes causes them to break, or blight and wither.

4. There is an insect, probably the Scolytus pyri, that eats a ring around the terminal branches, and causes their death above, on the apple, and sometimes runs down on the pear, and apparently causes the death below the part injured.

5. There is a blight on the pear, beginning on the parts exposed to the hot sun, and before this characterised as the sun-blight, sometimes also affecting a newly trimmed apple tree.

6. But there is also a worse form of blight than all these combined, which developed here in the most fearful ravages of the pear tree, quince, and privet bush, last season, and in some cases, affected the apple also. It is the real " Asiatic cholera" of pear trees; and I believe has never before spread among us in this county till last season. We suppose that we know, now, what you and your correspondents really mean by "pear blight," when you speak in your saddest and most despairing tones - and we have never Miy known before. But lest it should still be different from your forms of blight, I will try to describe it; for it is evidently very different from all the forms of blight mentioned above, in its origin and effects, and coincides only in the single fact, that the terminal branches appear to the careless observer, (but to no others,) to be first affected - just as in the other cases.

This form of blight differs from all the forms produced by insects above described, in the fact that it always begin* in the trunk and larger branches, and never in the small shoots of the tree: and it differs from what I described as the " sun-blight," in a former number of the Horticulturist, (Sept. 1849,) in the fact that the poisonous blotch on the limbs or trunk, is as likely to appear in cool, as in extremely hot weather; and as often found where the sun never shines, as beneath the full stroke of its rays.

Indeed, I am inclined to think it is the natural sequali, or terminatori, of that singular leaf blight which I described in the same article, of Sept. 1849.

The first fatal symptom that strikes the eye, as in the other cases of blight above nam* ed, is the blackening and perishing of the terminal leaves and branches. But by a careful microscopic examination, a dead and putrid blotch, or spot of bark, will always, (in this form of blight,) be found on the neck, trunk, or branches, of the tree below, which has thrown its poison first upward, and killed the tender terminal shoots, and then it again passes downward, and never stops till all the tissues are killed, at least down to the original plague spot.

This spot is most likely to be found at those points where the bark is changing from smooth to rough - either at the collar near the ground, or in or near the crotches and bifurcations of limbs and shoots. This, and other facts, induced last July, the suspicion that the cause must be either fungus or animalculss. And, after examining many hundred pear trees in this town and county, most of which are entirely ruined, I set about endeavoring to ascertain what was the cause.

I first spent a week in a thorough personal examination of my trees, root and top, with spade, knife, and microscope, at hand. I found nothing, save that the seat, or apparent origin of the disease, was as indicated above, and a confirmed belief that it was the work of fungus, or extremely minute animalcules, invisible with a common microscope. I accordingly procured a solar microscope of great power, belonging to the college apparatus, and in presence of Professors Adams and Batsman, cut a small bit of bark where I suspected the insects were, (if anywhere,) and placed it in the focus of the microscope. We all repeatedly saw an animaieuto, which, under the greet power of the glass, much resembled, in color and shape, the common " sow-bug," (as it is called,) running among the fibres of the bark, with about the same ease and freedom that a pig would run in a thicket. But we could none of us decide whether this animalouto was a cause, or only a consequence of the disease as multitudes of coarser insects will always be found around dead bark - evidently only because it is dead - and therefore gives them a proper nidus.

I made however, on this hint, a strong wash of soap suds and tobacco water, scraped all the trees thoroughly root and branch, and washed them all over, removing and burn-ins every dead piece of limb or bark. I also threw about one peck of coal ashes from a steam mill around the trunk of each tree. I was then obliged to leave for several weeks for the east.

On my return I was rejoiced to see all my pear trees greatly improved in health and general appearance. But whether the effect was to be ascribed to the changes in season, or to the treatment, or both, I cannot say as yet.

I shall continue my experiments next season, with some hope of ascertaining the presence of Fungus or animalcules, and a remedy for the same, if they exist, and hope others will do the same; and to prompt this research or inquiry is the sole object of this present paper.

Meantime I think the following points established:

1. It is certain that this form of blight differs from all others mentioned above, and from all other forms we have ever before had in this place.

2. It is certain that it begins its final destruction on the outer bark of the larger limbs, by a peculiar, though at first invisible poisonous blotch, which first throws up a poison, or something analagous to it, that kills the terminal shoot - while many feet of perfectly sound wood, bark, and leaves, may lie between the dead top and fatal spot, until at last the return current of sap kills all down to this blotch, and often below.

3. If this blotch is found, and all the dead parts thoroughly removed, especially if washed in spirits turpentine and lamp black, carefully, the limb above may be saved without amputation, but if any dead or poisonous bark is left, it will generally keep spreading from year to year, till all is dead.

• 4. It is probable that the disease really begins near the ground in the neck of the tree or its roots, and that the blotches in the crotches and rough places of bark above noted, are merely a secondary symptom of the disease, though they always precede the dying of the twigs.

5. It is probable that the black specks on the leaves in fall, and the red carbuncled spots on the bursting buds and younger leaves in spring and summer, are also premonitory symptoms of the same dreadful disease, which takes several years to run its full course.

All spots on the leaves and branches being an effort of the tree to throw off the annually accumulating disease, and the deadly blotches in the crotches and consequent dying of branches, only the fatal catastrophe of the previous course.

I ought more properly to ask if these things are not so. Let our friends this spring scrape away the dirt and carefully examine the condition of the necks of their pear trees under ground, and see if they do not find indications of a scurvy, rusty, disease; then let them examine all the bark above, especially all rough places, and see if the dead bark is peeling off and growing healthy as it ought to do, or cleaving down and turning red and black.

Then let them notice the condition of the blotches on the leaves in summer - of the buds in spring - and see if they do not find all this followed sooner or later, with sudden death of top* and branches, or perhaps the whole tree at some future year, soon after the commencement of the second growth in summer - in this way we shall sometime be likely, among as, to find out the truth of the nature and causes of some, or all of these various forms of blight, which I am sure we never shall do so long as we are content only to consider " a blight, a blight," and let it all go at that. I think there are some reasons for suspecting that the blight of the quince, pear, and privet, in this form, and the rot in the grape, and the rust in wheat are of kindred nature and origin - and if we can discover their nature and laws in either case, it will be productive of immense good. Let us all try. Yours truly, J. B. Tuura.

Illinois College, Feb, 1852.