of longer life than ours, we become naturally impatient to enjoy the products, and hence these devices to hasten its season of fruitage. Our course to this result is plain. Any expedient which checks growth without immediately endangering the life of the tree will effect it.

The ordinary and legitimate means to the end are dwarfing (see that head), summer pruning in June and July, or root pruning in August, or any other period of the year; or we may combine these means, if the health of the subject prove obstinate.

Whatever course may be chosen for the accomplishment of our object should be accompanied by a free supply of manures of such kinds as may not be calculated to stimulate mere wood growth. See Manuring Fruit-trees.

On the other hand, if we would strengthen a tree, or any particular part of it, we ought not to allow it, or that particular portion of it, to bear fruit; we should avoid summer pruning, and carefully invigorate it by liberal shortening at the winter pruning.

CHAPTER XIX.

Diseases of Fruit-trees.-Insects injurious to Fruit and Fruit-trees, with Remedies.-Washes to destroy Insects.

DISEASES OF FRUIT-TREES AND FRUITS.

FRUIT CRACK.

THIS is first indicated by the stunted appearance of the fruit, especially on one side, upon which a black crack or "chap" opens. It is accompanied by dark blotches upon the fruit, which are probably formed by the growth of a minute lichen, the fruit becoming ill-looking and worthless.

This disease, or effect of disease, is found in the pear, particularly the Virgalieu; in the quince also, and sometimes in the apple. It seems to arise from a deficiency in the supply of appropriate food, and is generally curable by manuring and careful culture. It may always be assumed that fruits subject to it require and will bear high cultivation.

BLACK KNOT.

This disease, which has almost entirely destroyed the damson, the horse plum, and some other kinds, comes at first as a green swelling, bulging out and spreading open with a granulated appearance, changing in color till it becomes a black, wart-like excrescence, being, in fact, covered with minute black fungi, which grow and seed upon it. In general, unless arrested by cutting out, it continues to spread, either by lengthening itself upon the branch or body, or by breaking out at some other points. When the branch is cut off, the stain of the disease is found extending for some distance below the knot, in the substance of the wood or at the heart.

It is perhaps more prevalent upon dark-colored plums than on the yellow or green varieties, and has become common upon the sour red and Morello cherries.

There are variant opinions as to its origin and character, some supposing it to be caused by an insect stinging the bark, various worms being often found in the knots; others regarding it as a vegetable cancer; but all agreeing that the only method of treating it is to cut it clean off the branches, and perfectly out of the body and limbs in its early stages, and burn every vestige of the cuttings, washing the wounds with brine or a solution of copperas in the proportion of one ounce to two gallons of water, or covering them with grafting composition or shellac. Perseverance in this course will be found successful in arresting at least its worst results.

BURSTING.

The trunks of certain trees, particularly the cherry, sometimes open and decay upon the south side, a result attributable to the occurrence of severe frost after the warmth of the sun's rays has started the circulation upon that side. The full sap vessels, we suppose, burst mechanically, as a full water-pipe is bursted by the same cause. Short stems help to provide against this difficulty, and trees placed so as to receive the slightest shade are seldom harmed.

LEAF-BLIGHT.

What is called leaf-blight in the pear, plum, etc., seems to be merely the result of a check given to the growth by heat or other cause, just as the hawthorn, refusing to acclimate well, annually loses its foliage in the summer or early fall, and becomes unsightly. It may be avoided in some measure, if not entirely, in fruit-trees, by good culture upon deep soils, moderately dry.

MILDEW.

Mildew is an appearance of mouldiness upon the young growth. Among fruit-trees it prevails upon some varieties of peach and nectarine, and upon grape-vines of foreign kinds. It generally follows a check in the growth by sudden change of temperature, etc., which is accompanied by numbers of a small aphis that punctures the back of the leaf and sucks the diseased juices; almost immediately the mildew proper appears, which seems to be a very minute vegetable growth.

It is removable by syringing or showering with a solution of an ounce of nitre to a gallon of water, with soap-suds, or lime-water, or any alkaline solution, or dusting with sulphur; but in respect to foreign vines can only be effectually met by renewing them every three or four years, either by layering from their own young shoots, or by young plants from other sources.

SOUR-SAP BLIGHT.

This disease is also called "fire blight," from the appearance of the tree destroyed by it; "frozen-sap blight," from the theory of its being the effect of frost upon the chemical condition of the sap in overgorged vessels, and by European cultivators the "canker," and is described by them as resulting from the sap being "corrupted by putrid water (i. e., in the subsoil) or excess of manure," and as working like a gangrene on the parts affected.

It is a disease of surfeit or plethora, often appearing in the pith near the points of very vigorous offshoots.

The change in the sap, from whatever cause it may proceed,

would seem to be a kind of acetous fermentation, running on to putrefactive poison, which is carried, with the very death it represents and includes, as far as the amount of virus produced enables it to spread.

It nearly resembles the form of death that occurs so commonly in young fruit-trees when planted where an old one of the same kind has died.

Dwarfed trees, and those of moderate growth, as the Seckel and Lodge pears, &c., are seldom subject to it, but strong growers in moist rich soils suffer greatly, or are entirely destroyed by it.

The selection of the less vigorous varieties, and the choice of dry and only moderately rich soils for the stronger growing kinds, may be resorted to where a choice in either respect is practicable. But if this can not be had, then let a careful and persistent system of root-pruning be pursued, reaching especially to the roots that strike down into the subsoil. If the effect of this is seen not to be too severe upon the growth of the tree, and not otherwise, follow it with moderate summer pruning. Where it appears only in spots, the diseased portion should be thoroughly cut out and washed with ley, or a solution of copperas (sulphate of iron), and afterward coated with grafting composition No. 3.

YELLOWS.

This is a jaundice or consumption in peach-trees, to which they have become liable within the last fifty years, constituting the only real difficulty in raising this fruit. It is variously accounted for, but no available remedy has been found. It has probably arisen from long-continued neglect of culture, combined with overbearing, the latter being incessantly stimulated, in addition to other causes, by the very weakness it produced. See Fruiting, page 258. A constitutional hereditary weakness, or disease, has thus been induced, which, when fully developed, becomes perhaps the very "essentiæ mortis," communicable by inoculation, as the virus of an animal body in a state of change, perhaps also by contact, or even by infection.

Its first and sufficient indication is the too early ripening of the fruit upon the tree, which as yet seems to be in health. This is followed, probably the very next season, by the growth of short feeble shoots from the obscure buds of the older branches, a change in the general aspect of the foliage, still more premature ripening or dropping of the fruit, which has now become darkly blotched with brown or purplish spots, beneath which the flesh is rotting, the tree becoming more and more sickly in its appearance until it dies.

The only known palliatives, or rather preventives, are moderate manuring, ordinary summer cultivation of the ground, so as to secure for them regular plowing, &c., which this tree feels almost as quickly as a cabbage; the choice of an exposed situation, to avoid winter killing, to which, in northern latitudes, it is liable when thus treated in warm exposures; and the annual cutting back of all young shoots to one half or one third the length of their last season's growth, with such other winter pruning as the condition of the tree may seem to require.

Severe winter pruning and good culture immediately after the occurrence of the first indication will, to all appearance, perfectly restore the tree; but if these are discontinued, it returns the following season to its former state.

INSECTS INJURIOUS TO FRUIT-TREES AND FRUIT. For general remarks upon insects and their habits, see page 94.

As certain plants are supposed to serve as a protection to vegetable crops, so certain essences, &c., hung in vials in the trees, have been suggested as a defense for fruits. For this purpose, the essences of peppermint, tansy, and pennyroyal are sometimes used; also, spirits of turpentine against the rose bug, and ammonia as offensive to the plum weevil.

Decoys, or wide-mouthed bottles half filled with sweetened water, have been used with good effect for catching wasps and the larger bugs; and it is said by a recent writer that these are much more efficient if the mouth of the bottle be closed, and an entrance made by breaking a hole in the side. Once in, the insects do not so readily find the way out.