The Apricot, as has already been hinted, starts into activity at the earliest approach of spring, and, as a consequence of this, produces its bloom at a time when we often suffer much from sharp frosts in the morning. It is therefore of the greatest importance to use some artificial means whereby to guard against the evil consequences which would result from exposure to even two or three degrees of frost. Various plans have been adopted at different times by cultivators, but the best, to my mind, is that practised at Floors Castle by Mr Rose, now of Frogmore. The Apricot-wall there has a western aspect, so that the reader will observe it is not placed in what, for Scotland, is generally considered the best position - viz., the southern; yet, from several years' observation, I can state that wall never failed to produce a crop of first-rate fruit. The plan adopted was as follows: - When the buds began to swell, poles were obtained reaching to the top of the wall under the cope, while their bottoms rested upon the border 3 feet or thereby from the base of the wall - the tops so secured as that there was no chance of being blown over by wind: this having been accomplished, woollen netting - one net of which is as good as ten of the ordinary kind used for this purpose - was fastened to the cope and allowed to hang loosely down over the poles.

Small blocks were placed at equal distances along the wall, and tackle adjusted thereto, by which means the netting could be drawn up and down at pleasure. Whenever a frosty night threatened or cold winds prevailed, these nets were run down; but during the day, when the weather was fine, they were invariably drawn up. A broad temporary wooden coping has been recommended and extensively used by some of our lead-ino; horticulturists. The breadth used is from 9 inches to 1 foot, and it has often proved very serviceable for the purpose intended. Yet we cannot shut our eyes to the fact that if a sharp wind were blowing with the frost, the chances are that not more than 2 or 3 feet of the upper surface of the wall would be saved even with 1 foot of coping. Others, again, use Spruce branches or Fern branches, which are hung regularly all over the surface of the trees; and from the labour necessary to place them there, it will be obvious that they must be permanent until their work is accomplished. This I consider the worst of all protections, and would scarcely recommend it unless no other could be obtained.

Among the many arguments which might be brought against this mode is the very obvious one, that while the trees are protected from the severity of wind and frost, they are also denied the benefits to be derived from the genial influences of the sun and light. The young fruit, as it begins to form, assumes a pale sickly appearance, very different from the bright healthy green look natural to the Apricot; while the shoots and leaves become weakly and "drawn." Such wholesale covering cannot, therefore, be good; for although, under this system, young vigorous trees may produce good crops of fair fruit, yet I doubt not, if other and more natural means were adopted, a good crop of better fruit would be the result. Trees protected by the methods just alluded to cannot be expected to be so hardy as to allow the total removal of their covering at one time, yet from the nature of such coverings it is impossible to do otherwise; and the consequence is, they will often suffer as much, after its removal, from the effects of 4 or 5 degrees of frost, as they might have suffered had they been entirely left to the mercy of the weather without any protection whatever, or even more.

The method of protection which I have recommended as the best for this period, will also be found to be the best for protecting the fruit from the ravages of wasps and suchlike when the fruit is ripening, unless where hexagon netting is used. While wool-netting, which is generally about 1 inch in the mesh, will keep out birds, it will at the same time prevent wasps, which are great devourers of the Apricot, from entering, as they dislike wool so much that they will not alight upon it, and without alighting upon it they will not attempt to pass through.

As soon as the Apricots have set, and are about the size of a large Pea, the fruit should be thinned out to about half the distance that it is intended to bear the crop. In the smaller-growing varieties, 4 to 6 inches, and in the larger kinds 9 or 10 inches, will be found to be a good distance for the crop. To the half of these distances let them at this stage be thinned, and when thoroughly stoned the superfluous fruit may be removed.

The principal diseases with which the Apricot is attacked in this country are gum, canker, mildew, and that mysterious dying-off of the branches, and sometimes whole limbs, during the growing season. The exudation of gum is generally, though not perhaps always, the result of some external injury. Undue twisting or bending of branches, to the breaking of the bark or injury of the cellular tissue, is in every case followed at an earlier or later date, according to the extent of the damage, by an exudation of gum. Sometimes, at the nailing season, by a slip of the hand of the operator, the hammer may fall upon a branch and injure the bark; this also is the precursor of this disease. There is no known remedy for it, so that every care and precaution ought to be exercised to avoid the slightest injury to the tree which might lead to this result. Canker in the case of the Apricot, as in everything else, is the result of the tree being planted in an uncongenial soil, or when the roots penetrate down into a bad subsoil. Whenever the first symptoms of it appear, means ought to be adopted to prevent its further progress, and to reestablish the constitution of the tree.

To accomplish this, the tree ought to be well root-pruned, having all rank and watery roots removed; after which a good supply of fresh soil ought, if possible, to be procured, into which the tree may be planted: this will for a time, at all events, stop the further progress of the disease. "Mildew appears," Mr Knight has stated (see 'Horticultural Transactions,' vol. i. p. 86) "to be the want of a sufficient supply of moisture from the soil, with the excess of humidity in the air, particularly if the plants be exposed to a temperature below that to which they have been accustomed." This appears to be a fair statement of the case; and so far as my own experience has gone, it was only under such circumstances that I have seen mildew attack the Apricot. The best remedy is an application of sulphur upon the first appearance of an attack. The cause of the dying-off of portions of a tree at the growing period is involved in considerable mystery. Various are the reasons given by many of our best horticulturists regarding the matter; but most of these opinions are mere speculations, and by them only given as such. Some have said that it is the result of sunstroke, others that it is through injury sustained by the sap-vessels through the agency of frost.

I am rather sceptical regarding either of these being the cause, as I have noticed that branches which die in this manner often show a weakness for a year or two previous to their death; while if sunstroke were the cause, death would follow in a very much shorter time. On the other hand, I have noticed that branches die in this fashion as often after a very mild winter as after a very severe one; therefore I hardly think frost can be the cause of it. If I may be allowed to speculate regarding the matter, my theory is that it is the result of the branch becoming bark-bound. This will account for the branch showing signs of failing health for a year or so previous to its death. By slow degrees the bark gets tighter, and the wood, in attempting to swell, failing to find space to grow externally, presses upon the fluid-tubes in such a manner as in the course of time to almost close them up. Having arrived at this stage, the branch pushes its buds into leaf, and all goes well for a time; but whenever a day of strong sun or of parching wind comes, the fluid-tubes become unable to supply the necessary amount of food for the growing appetite of the quickly-developing leaves, and the result is that all at once the branch flags and dies off.

I may be wrong in this speculation regarding the matter, but it may be cleared up in the course of time. Let a few gardeners in various parts of the kingdom, whenever they see the least appearance of the disease, run their knives longitudinally up the branch so affected from the main stem for some considerable distance, and in three or four places round the branch, and if the cause is to be attributed to bark-binding, the above will prove to some extent a cure. I have not adopted this theory long enough to be able to prove the matter, but hope in time to do so. If those who may try the experiment would have the goodness to report their results of it in the pages of the 'Gardener,' I have no doubt the Editors would give it a place for the benefit of their many readers.

There are various insect enemies to the Apricot cultivator; the first of these is the Curculio tenebricosus, which is a small and very destructive beetle. It secretes itself under the loose bark, and in crevices and old nail-holes in the wall. The best cure is to have the walls freshly painted with lime, and the loose bark removed from the trunk and branches of the trees. In winter let the trees so affected be thoroughly syringed with a strong decoction of tobacco, and in most cases it will prove effectual.

The Tortrix Woeberiana, although not a very common enemy, is, however, a very injurious one, as its depredations upon the branches in many cases result in the exudation of gum. The larva is of a greenish colour, with a red head. Its presence is indicated by accumulations of reddish-brown heaps upon the branches. Under these heaps will be found a small tunnel, in which the larva is lying and feeding upon the inner bark of the tree. Two generations are yearly produced, the one in May, the other in August. The best means to destroy them is to thrust a needle down through their abodes, whereby they will instantly be destroyed. Mr M'Intosh recommends painting the branches so affected by a solution of lime on the first appearance of the enemy.

The Ditula angustiorana is a greenish caterpillar, which, feeding upon the leaves, does considerable damage. It makes its appearance in May, and forms itself a home by binding together the extremities of the leaves, which, as they continue to grow, become curled. In the course of a short time it changes into a chrysalis, from which emerges the perfect moth in the month of July. The best means to destroy these is by hand-picking, which ought to be repeatedly and carefully done during the early part of the summer. James M'Millan.

(To be continued).