I now come to speak of the diseases to which the Apple is subject in Britain; and first of all I would refer to canker. This is the greatest enemy, and perhaps the worst to master, of all the ills against which the cultivator of the Apple has to contend. As I hinted in a former portion of this article, it is my humble belief that it is both constitutional and hereditary to a very great extent. My conclusions on this point are arrived at after long watching and close observation made upon hundreds of varieties of the Apple. It must have been observed by all gardeners that several varieties are far more liable to canker than others which may be growing side by side with them in the garden or the orchard. And, further, I have seen young trees (maidens) received from the nursery apparently in the best health, which, during their first year's probation, succumbed to the ruthless power of canker. How is this to be accounted for 1 What answer, my reader, would you give to your master if the half of a quantity of young trees bought in during the current year should die upon your hands ere 1870 should close over your head % Very probably you will say, "Why, sir, they have died of canker." Now this is all good enough so far as it goes, but should he further argue that canker is a disease which is brought on by surrounding circumstances - either a wet subsoil, a bad climate, a wound from the spade, the hammer, or the knife; and that he cannot see why in the course of one short year canker should have destroyed one half of the trees - what would you answer 1 If you will allow me, I will tell you what answer you ought to make.

It must be evident that for one year they cannot have been so badly managed as to bring the disease upon them to such an extent, so the answer must be that the disease in this case was constitutional and hereditary. In such a case as this, the scions must have been taken from old trees full of the disease, which, however, the energy and power of a healthy stock have prevented from yielding to its baneful influences while in the nursery and during its first year's growth. The lifting, however, with the subsequent transportation and replanting, works a wonderful change. The stock by the operation loses a considerable amount of its strength and vigour; the roots have been cut and pruned so that the plant loses a considerable amount of its feeding powers, and with it the constitution is to a certain extent reduced - not, however, so far as to be of the least injury to a healthy plant, but far enough to do all the evil possible where the tree has already got the seeds of disease flowing through its blood. This reduction of the strength and vigour of the tree gives the first opportunity to the disease to make its appearance.

While the stock is struggling to overcome the check sustained by transplanting and root-pruning, the circulation of the sap is neither so great, so swift, nor so regular, as may be easily seen from the late start and weak shoots formed by such a tree when compared with one which has not been removed; consequently, the discharge from the tree to the soil will also be less regular and less in quantity. If this be the case, as it must be, then the tree to a greater or less extent must be living upon itself, and the seeds of the disease are thereby getting an opportunity to disperse themselves over the whole body thereof. As soon as this has taken place the case is hopeless - the tree is doomed. No known power of the gardener can save a tree when it has arrived at this stage. He may struggle with it and cut as he will - his labour in the end will be lost. This is a lesson to us all, which shows us how much we are in the power of the nurserymen; and I am sorry to think that so much of the want of success in fruit cultivation is due, not to the mismanagement of the gardener, but to the carelessness of the nurseryman and raiser of fruit-trees. I will not deny the fact that there are a few good firms which may be thoroughly relied upon to provide good and healthy trees true to name.

For every firm, however, for which this can be said, a dozen can be pointed to which are just the reverse. Now it would be good for gardeners, and it would be good for nurserymen themselves, if this were not the case. How much more satisfactory it is for the buyer, and must also be for the seller, where everything gives satisfaction! That satisfaction may be given, it is necessary that the scions be selected with the greatest care from trees of the most undoubted health, where canker never has been. It is very often the case, however, that the scions are obtained from some garden or orchard near by, and some young man is sent to gather them who neither "kens nor cares" whether they are from healthy trees or not. In this case he gathers all he can lay his hands upon, from trees old and young, healthy and diseased; he puts them into bundles which go into the nursery to spread the disease - I had nearly said from pole to pole - from Land's End to John o' Groat's. Avoid, therefore, the diseased parent if you wish to become the possessor of a healthy offspring, for the seeds of disease in the parent stem are sure to manifest themselves in the sapling twig.

Although both constitutional and hereditary, canker is also a disease which may take hold upon the Apple through the effects of surrounding circumstances. In short, canker in this form is nothing more nor less than the want of constitutional vigour for a lengthened period. If a tree is so placed that the food within its reach is not of the kind and quality necessary for it - if the temperature of the soil is too cold or too wet - then the inevitable end of the matter will be canker and decay. It will be years, however, before it makes its appearance in a tree which has been healthy and good in a young state. As a rule, if the soil of the garden is at all like suitable for the Apple to the depth of 18 inches, it will be very bad management indeed if canker should make its appearance during the first dozen years of their existence there. If the instructions already laid down are attended to with regard to root-pruning, etc, it may be avoided altogether. It will thus be evident that root-pruning serves a double purpose - first, in bringing the young tree into a good and early fruit-bearing condition; and, second, in keeping it in the same by guarding against canker, and keeping it in a genial temperature and within reach of wholesome food.

It will be quite unnecessary for me to enter into details explaining what canker is, as it is well known by every one who has ever had the most limited collection of fruit-trees under his care. In the case of receiving under one's care a collection of trees which are suffering to a certain extent from this disease, the first thing to be done, if the trees are worth the trouble, is to have them lifted and examined, the bad roots cut away, and the tree planted in good fresh soil. Let the branches also be examined, and all cankered portions at once removed. This may prove of very much advantage to the tree for many years, yet the fact need not be disguised that the tree will never be the same again as if it had not suffered from the attacks of the disease. I would almost recommend in every case of this sort that a collection of young trees be bought in to take the place of the older ones; retaining the older ones, however, until such time as the young ones are brought into a fruit-bearing condition. Although old ones may give satisfaction for a few years, yet nevertheless, if they have suffered from an attack of canker, the health and vigour of treehood, if I be allowed to make a word to answer my purpose, will have gone for ever.

I know of no disease to which humanity is heir which is so analogous to canker in a tree as that of consumption. Now admitting this fact, it must be evident that a tree which has once suffered by it can never be the same again, for it is a well-ascertained fact that a man who has been cured from the earlier stages of consumption has never the vigour and energy of one who never has been attacked at all.

Mildew is another disease which frequently attacks the Apple, especially in dry seasons such as the present. Some kinds are more liable to its ravages than others. The more delicate and tender sorts often suffer much, while those of a stronger constitution escape, thus giving effect to the general law of nature that the weak shall suffer first. Mildew makes its appearance upon the young leaves and shoots of fruit trees early in summer. A deposit of matter, giving the branch the appearance of having been dusted over with flour, makes its appearance. When touched with the finger it has a soft uncomfortable feeling. This matter is no less than a parasitic fungus, having life and growing, and in course of time sending off millions of little spores, which, borne upon the wings of the wind, may be carried to far and distant climes, there to work havoc upon the fruitful trees of sunny lands. I am of opinion, however, that dryness is not the sole cause of its appearance, and that it is not created for the time being and then for ever dies, but that it lives and dies generation after generation, the same as any other member of the vegetable kingdom.

Seeing this to be the case, I further believe that cold easterly winds help to bring it to us; that it would matter little whether the season were dry or not; if the wind kept always in the west, we would have little or no mildew upon our trees. I am therefore of opinion that the state of the atmosphere during cold sharp east winds is such as to be most conducive to the spread of this disease. Then it is dry, searching, and sharp - the spores will also be dry, light, and easily upborne; and with all these things working together for its migration, it need not be doubted, and I firmly believe, that it may fly for hundreds of miles, borne upon the wings of the wind, ere it lodges upon the branches of our trees, and becomes the mildew of the fruit cultivator. Dry sulphur, blown on with a sul-phurator or sulphur-box while the dew rests upon the branches, will be found to be the best remedy which can be applied.

James M'Millan.

(To be continued).