Dear Sir - Many of your readers living in the sea-board states, have in their gardens old pear trees of fine sorts, principally St. Michels, Butter pears, St. Germains, or other well known varieties, that have fallen into disrepute. The reason of this, as most of the writers of the day affirm, is, either that the varieties are worn out, or else the soil is exhausted of the food that once enabled these trees to bear such fine crops of beautiful pears, as they were once in the habit of doing, annually.

I suspect there is some truth in both these conjectures. In other words, I do not believe the fine old pears, such as the St. Michel and St. Germain, can by any process be restored to precisely the same state of health and productiveness that belonged to them forty years ago, in this part of the country; but at the same time, I think it can be easily proved that they can be made productive, and that a worn out soil is practically the cause of much of the degeneracy which we see here among the fine old pears.

Tour readers will no doubt remember some brief directions which you gave in one of the early volumes of the Horticulturist, for renovating old pear trees. As several of my acquaintances in this county have tried the experiment, and as I have myself, dabbled a little in the matter, I hope you will allow me to make a few comments, with a view to contributing something to the stock of useful knowledge on this subject.

The principle assumed in the directions given to renovate old pear trees, is, that the soil of our worn out fields and gardens, has become deficient from long cultivation, in the mineral substances needful for the perfect growth of the fruit. These substances are especially lime, potash and phosphates. In order to supply these deficiencies, it was recommended to apply liberally, lime, ashes and bone dust. This was coupled with directions to add fresh soil, rejecting the old soil, and a considerable quantity of animal manure.

As many persons like to get at a given object with as little trouble as possible, they have doubtless failed in recovering old pear trees, because they have trusted solely to a liberal top-dressing of the said ashes, lime and bone dust. Such top-dressing will, of course, benefit a young and healthy tree - but they are by no means sufficient to renovate one that has stood in the same place for twenty or thirty years - and exhausted the soil as far as the roots extend, of not only the necessary mineral, but also animal or vegetable matters. I will recount the treatment of three trees that have particularly come under my own inspection, to illustrate this position, as well as to show the real value of the mineral manures.

These three pear trees were all of the St. Michel or Doyenne variety. They stood on the north side of an old kitchen garden - were all about twenty-five years old - had borne many good crops of fruit - but had cracked and failed for ten years past.

To begin, all these trees had trenches dug round them, and the roots were partially laid bare of the old soil.

The first one, (which I shall call No. 1,) had good soil put back, mixed with half a bushel air-slaked lime, two bushels ashes, leached, and half a peck of bone dust.

No. 2 had no lime or ashes, but about three cart loads of strong stable manure incorporated with the fresh soil that was filled in the trench and about the roots.

No. 3 had the same quantity of lime, ashes and bone dust, as No. 1, and the same quanThis is now three years ago. All the trees have greatly improved. No. 2, which had only manure, has made a good growth, but the fruit is still imperfect. No. 1, which had only the mineral manures, bears much better fruit than it formerly did, but the tree is not vigorous. No. 3, which had a plentiful supply of both mineral and animal manure, is not only very much the most luxuriant tree, but is loaded with a crop of St. Michels that reminds me of "old times."

Does not this experiment prove that to renovate an old pear tree, it is not sufficient to give it lime, potash, and the like? I think so. But there are other points which are worth a moment's attention.

The first is, that an old tree, with stunted short branches, which have grown perhaps only two or three inches per annum, for five years past, is not in a condition to be roused into healthy growth, even by both kinds of manures. For such a tree, it is necessary to use the knife, in order to force the tree to re-act or rouse itself a little - to make new wood - to put out fresher and larger leaves - in short, get up a new set of sap-vessels at the extremities, which are not so choked up and sluggish in action as the old stunted ones.

The right way to do this is to shorten-back the ends of the limbs - say from six inches to a foot, all over the tree. The more the tree is stunted - the more it should be cut back. But never "trim out" the large branches of an old pear tree severely - as this often has a tendency to cause the fire blight. The shortening-back may be done in early autumn or spring. I prefer March. The best time for the "renovating" is in the autumn.

The second point, is to keep the tree well mulched over the surface of the ground that covers the roots. The best things for this purpose I believe to be salt-hay - or tan bark. It should be spread as far as the roots extend - or better still, half as far again. The roots of trees actually luxuriate in the cool and moist soil that is always to be found under the mulching - even in this hot and dry season, when otherwise, the top soil would be as parched as powder.

Although I have given you but three examples of pear trees renovated, I have seen several others which go to illustrate with greater or less force the facts I have stated. The older and more stubborn the subject, the more it becomes necessary to give it a very liberal supply of both animal and mineral manures. But once applied in the manner I have directed, it will not probably be requisite again for several years, or perhaps an annual top-dressing of the same substances would be sufficient for a long time afterwards.

I am sir, yours, A Boston Subscriber.

Boston, Jug. 1851.

We thank our Boston Subscriber for his practical communication, which we cordially approve. Old pear trees that have become barren, need an abundant supply of animal manure as well as mineral, to rouse them into a state of renewed growth and fruitfulness. We were present lately at a discussion which took place respecting the application of substances to renovate old pear trees - in which one of the experimentors declared his utter failure and want of faith in any such results. Another gave an account of a fine old tree most completely renovated by a plentiful drenching of the soil about its roots with "bullock's blood," one of the most powerful of manures, containing both organic and inorganic food for plants. Ed.