The Olive Its Culture in Theory and Practice/Chapter 6
Multiplication of the Olive
CHAPTER VI.
"Quin et condicibus sectis mirabile dictu Truditur e sicco radix oleagina ligno."
Virgil, Georgics ii, 30.[1]
The olive is propagated in many different ways, by seed, by cuttings, by truncheons, by grafts, by suckers, by knots, by layering, and by pieces of the root.
SEED.
The best method, in spite of all that may be urged against it, because the natural one, is the planting of the seed. All others are mere continuations of a life already existing but with each seed is produced, in the manner intended by nature, a new tree. The non-success that has attended many efforts to raise the olive from seed in California, undoubtedly arose from faulty handling. Some go so far as to claim that the Mission olive contains no germ. This is absurd. The Mission olive contains well developed seeds in the same proportion that all others do, viz., the poorest olive for oil or pickling is the best for seed. The olive nearest approaching the wild type, the olive that contains the largest seed in proportion to the berry, is the best for planting. One tenth of the stones of the wild olive have a double germ and this is the best of all olives for seed, second the Mignolo, third the Razzo, Leccino, Puntarolo and Trillo, fourth the Grossajo and fifth the Morajolo.
A tree grown from seed, has a long tap root, and a very straight smooth stem, which shows the vigor of the plant; while a tree raised in any other way has not these advantages. Its pivot root gives it a force that other trees do not possess. It is more productive, will resist diseases better, and is a hardier tree than one raised from a cutting.
When the ground is loosened by rain, and the tree is loaded with fruit, a heavy wind sometimes overturns the olive, this could not happen to a tree from seed, its tap root takes too firm a hold. This accident occurred on the Quito Farm in the winter of 1886, and the trees which were so unfortunate had to be replanted and cut back to the crotch being lost to the place as fruit bearers for the next four years.
Again the time lost in raising from seed is more apparent than real, for, after the early years of its life, the advantages are wholly in favor of the tree raised from seed. The weight of opinion, derived from an experience of centuries, favors this method.
In 1882, the Congress of the Italian Agriculturists, meeting at Bari, arrived at the following conclusion:—That persons be recommended to raise their olive trees from seed, in preference to any other method.
If proof were needed that the olive will grow from seed in California, we have it in the fact that various parties have successfully raised the Mission olive in this way. Whatever seed may be sown, the resulting plant will be the wild type, and should be grafted, in the nursery, when from two to three years old.
By actual count on the Quito Farm, one hundred Mission olive pits gave fifty well developed germs.
To hasten germination the seeds should be stripped and soaked in lye for two or three days, then dried and placed in a dry spot, or disposed in layers in a box with dry sand, being well covered with earth to keep out water. When the time comes for sowing, sow the seeds without detaching the sand that clings to them. Some writers suggest that they should be fed to domestic fowls as the best way to strip them; and passing them through a goat is said to be the best mode of all. Olive seeds unstripped never germinate in less than eight, nine and twelve months, and when the berries are under ripe even in two years, and sometimes not at all. Care should be taken in selecting berries for seed, to choose only such as are thoroughly ripe.
To save loss of time, and assure oneself of there being a seed in the olive, break it with a hammer, strike a single light blow so as not to injure the seed, or a still better but slower way is to use a vice. So treated the buds will come out in thirty to forty days.
For bed, dig a foot deep, manure it richly, plant the cracked seeds at a depth of two inches and about four or five inches apart. Where there is no danger of winter frosts, the planting may be done in October and November, but where this drawback is feared, February and March would be the better months. Careful cultivation is necessary. When the trees are six to eight inches high, that is, when about a year old, they should be transferred into a nursery. In transplanting, the roots injured in the process should be trimmed down, and the lower one-third of the tap root cut off at the point where it begins to grow noticeably small. Also the lateral branches should be cut off, leaving only a leaf on the main stem where the branch intersected. This increases the growth of the young plant and makes a straighter and finer trunk. If the laterals are left on, they receive the nourishment first from the roots to the detriment of the plant. If cut off later, as must be done, the wounds to the tree are larger, and so the tree is harmed. The leaves must be left on, as they fill the necessary office of absorbing the carbonic acid, so necessary to the life of the plant. With the young tree raised from a cutting, on the other hand, it is unnecessary to take off the lateral branches, the aim being to stimulate root making; the cutting having none.
In transplanting to permanent position from the nursery, there are two methods of treatment each having its advocates. One is to cut off all branches in order that the strength of the tree may go entirely to root making, and the other to leave the five six or seven branches forming the head.
In the first instance the new branches are apt to put out half way up the stem, when the plant has to be cut down to them, and the result is that the head is formed too low. On the other hand in transplanting with the head formed, these branches are apt to suffer at first from lack of nourishment, and so check the growth. The good of the tree would be consulted by taking off all branches, but if the head can be left on, fruiting will be anticipated by about two years. In truth the good features of each method may be adopted by leaving the head on, but clipping the branches very short. The tree may also be compelled to branch at the desired height by bending down the little branches forming the head, and tying them to the trunk during the two years proceeding its removal from the nursery. This will cause the sap to accumulate there, and when the tree is deprived of all its branches at the time of transplanting to a permanent position, the new branches will come out there in preference to any other part of the tree. But the tree is the more vigorous as the trunk is kept short. In setting out in permanent position in orchard if on level land plant, from two to four inches deeper than in nursery, and if on a hillside from four to eight inches. A layer of chaff or cut straw placed about the tree just before filling up the hole, will serve to retain the moisture in the soil. In removing trees from the nursery to final locality, mark the south side so that they may be replanted in the same position. If this is not done the tree often remains stationary for a long time. Some writers have advocated reversing the former position with the idea of equalizing the growth, but this appears to simply stop the onward march of the tree where it might be gaining all the time; or were any equalization of growth necessary it could be accomplished in the pruning. The young trees should be topped with an inclination of south to north and the cut always covered with grafting wax. A grove of olive trees should be planted so that at the spring equinox no tree will cast a shadow on its nearest neighbor from south to north.
CUTTINGS.
This mode of propagating the olive is popular in Spain and in certain parts of Italy and Sicily. It was also known to the ancients. But in many localities it has been abandoned as being too uncertain. For cuttings take clean and well sized branches of from one to four inches in diameter, and cut in one foot lengths. These should be prepared in winter, before vegetation commences and the buds move, but if they are not immediately planted, they should be kept covered in a moist, cool place. The essential conditions for rooting are, moderate moisture in the soil, a subterranean temperature of about forty-one degrees F., with an atmospheric average of from fifty to fifty-two, thus giving time for the roots to form, extend and strengthen in advance of the first dryness of spring and early summer. Cuttings put in in April or May, root quicker but demand more frequent irrigation. Those will do best, which before being cut off from the mother branch, have been either ringed, or burned, or skinned, below a bud, so as to form a knot above the wound. There are many different ways of putting out cuttings. They may be planted in a trench well manured, each two making a triangle, the bottom of the trench being the base, and the two cuttings meeting at a point and being covered with from three to four inches of earth; when the young shoots have attained sufficient size to transplant, they may be torn away with a quick jerk, generally bringing with them a strip of bark which will suffice as a root, and leaving the parent cutting in place, where it will immediately produce more shoots which may be treated in the same way.
Very good results have been attained by planting a cutting horizontally, and covering it with four inches of earth; by some this method is preferred to any other. It is desirable that the cutting should be entirely covered with earth, as otherwise the sun will check and burn it, so as to make any good result impossible.
For California orchards, where as speedy an issue as possible is desired, if two cuttings are planted together in the spot where the future tree is intended to grow, the outcome will probably prove satisfactory. The two cuttings should give birth to at least one tree, and this never being disturbed by transplanting, will make an extraordinary growth. Should more than one tree make its appearance, the extra ones may be used to supply those that fail altogether.
The smaller the cutting the greater is the necessity for planting it horizontally.
TRUNCHEONS.
The question is often asked, how long before the olive will bear fruit? In answer to this, it may be said, that it depends very much upon the size of the wood planted. A truncheon sometimes bears in the following year from that in which it was put into the ground, and generally in the third year. But it must be well understood that it is at the expense of the tree. Cuttings, insomuch as they are so near the surface of the ground, demand greater care than truncheons, being exposed to danger from animals and frost. But if they survive these early perils, the vigorous shoots of the cutting soon equal the truncheon in size, and at the end of fifteen years pass it in the race. The tree grown from a cutting is lustier, better shaped, and more productive than that from a truncheon. The latter solely has the advantage of bearing more fruit in its youth, but it is at the expense of its growth.
An olive truncheon, is a limb of the thickness of a mans arm, and from seven to ten feet in length, of new smooth wood, free from warts or scratches, the most vigorous and healthy scion of the tree it is proposed to reproduce.
From this, it will be evident how difficult and costly it is, to obtain any number of truncheons that should unite all these qualities; especially as the tree has to be pruned, with this object in view, for three or four years beforehand. As may be imagined, a tree that has been robbed of three or four truncheons, is not improved in appearance, and it takes much time to cover up the space left bare. The limbs once cut off, should be placed in the holes prepared for them as soon as possible; so much so, that both acts should be performed simultaneously, but if through an unavoidable delay, owing to distance of transportation, or some similar cause, the truncheon should have dried somewhat, soak it in water for a day or two, and then put it in wet earth to a depth of two, or two and a half feet. But after all said and done, do not fail to plant it as soon as possible. Supposing everything to be ready, first throw a shovel full of well fermented manure into the bottom of the hole already prepared; this being the more necessary the less fertile the soil, over this an inch and a half of some of the best top soil, then place the truncheon upright in the center and cover with good top soil taken from another spot, press down with the feet, and leave a slight depression about the plant, if there is a prospect of rain, or if it is proposed to give it water. After watering, or a rain, the ground which has settled should be replaced, and then heaped as high on the plant as possible. The warmer the climate, the more necessary this will be found.
In the south of Spain, and Portugal, where this method is practiced, it is customary to build up on the plant, a cover of mud to a height of five feet leaving only one foot of it exposed, where it buds.
The advantage of covering a plant in this way, is plain, as we know it evaporates its moisture, and having no roots to absorb with, the more sun and air it receives, the faster it loses the elements that are to help its growth. So truncheons are often seen with the upper part dead, and dry from the heat of the sun; then, they bud from below. When covered, this rarely happens. Half way up the mud cover, a little hole is made, through which to give them water during the first year.
Where irrigation is practiced, they do not need to be covered; but otherwise even a layer of grass and weeds, to prevent the direct action of the sun and air on the bark of the truncheons, is of great use. The height which the truncheon should show above ground, should be forty to eighty inches, the greater, in the warmer climate, and the less, in the colder place. The growth of the truncheon is such, that it gives a crop in the third year; whereas the cutting does not bear until from the sixth to the eighth, and then not so plentifully as the truncheon. But the olive tree from a truncheon does not root as well, and is never as vigorous, as that grown from a cutting.
To grow truncheons, instead of despoiling and deforming the trees, is the much wiser course. For this purpose make a trench twenty inches deep. Select branches that will average more than two inches in the narrowest part, and cut them into lengths of twenty inches. Place these upright in the trench, one yard apart, and cover with earth. If on watering, or after a rain, the upper ends are uncovered, carefully cover them again, to protect them from the sun. Towards the end of spring, the truncheons will sprout, and the thicker, cleaner, and newer they are, the more vigorous will be the shoot.
As soon as the young sprouts are seen, the ground should be spaded over, the earth carefully scraped away from the plants, and fresh earth added. In the beginning of July, the ground should be worked over, and again in the early part of August. In parts of the country where irrigation is necessary, they may be irrigated, but generally frequent cultivation, and freedom from weeds, is sufficient to insure a favorable growth. In the spring of the second year, open the trench, uncovering the mother cutting. Sever at the neck of the plant all superfluous shoots. The aim should be, to leave one, two, or three, vigorous ones so distributed around the parent cutting, as not to interfere with each other. In the spring of the third year, again open the trench, and cut off any sprouts that may have started on the mother cutting. Also, if the lower branches of the two or three shoots of the year before, interfere with cultivation, or are growing out of proportion to the tree, prune them as may be necessary.
In the month of March of the fourth year, the plants will be sufficiently advanced to serve as truncheons. Again the trench is uncovered, until the union of the truncheon with the wood originally planted, is visible. Seizing this, with a steady pull, tear it from the mother, and with it, will come away some roots, and part of the original bark and wood. These are most necesary to its perfect rooting. We now have a truncheon, and it must be planted in the manner heretofore described.
The original wood, from which there has been torn one, two, or three young trees, will put out fresh shoots immediately, and go on producing other trees, and the treatment must be the same as that already described.
Fig. 1. Crown Grafting.
A.—The stock.
C.—g. The graft.
e. e'. e''.—The scions inserted.
B.—The incision in the bark of the stock to admit the graft.
GRAFTS.
The olive can be grafted in several ways; two methods are the most appropriate—crown and shield grafting. In crown grafting the operation is performed when the buds are grown a third of an inch long. Cut horizontally the head of the stock, or the branches only of the second or third order, according to the age of the tree, at about eighteen inches from their spring. Then, cut through the bark to the wood, in a vertical line, about two and three-quarter inches long.
Cut the lower part of the graft in a pointed form, with a notch on the upper part. Raise the bark of the stock, and introduce the graft, between the bark and the wood; surround with a bandage, and cover with mastic. This sort of grafting is used for old olive trees. If more than one is used, a clear space of three inches should be left between each.
Fig. 2.  f f. The bud selected. f. g. g. g. f. Side view of bud. H. The bud. |
Fig. 3  A. The Cut. B. The bud inserted. C. The binding and securing of the bud. |
BUDDING OR SHIELD GRAFTING.
The piece cut from the bark to form the graft is most frequently in the form of a shield. This piece of bark must have upon it, near its center, an eye or bud.
These grafts, are especially used for young stocks, or branches from one to four years old, having thin, smooth, and tender bark. Shield grafting, with a dormant bud, is practiced towards the end of the summer, according to the vegetation of the subject. The head of the stock must not be cut off until the following spring, when it will be seen whether the graft bud has been successful.
The following are the principal points to be attended to.
1st—Cut from the olive tree a branch having some leaves, or eyes at its base, or buds well developed. Take off the leaves, leaving only a small piece of the stem of one of them, to hold the shield by, between the fingers. Keep the grafts, or buds, when thus prepared, in a dark, cold, and damp place, until the time that they are required for placing upon the stock.
2d—Make an incision in the form of the letter T, penetrating to the wood, and separate with the spatula, the two lips of the bark towards the top.
3d—Separate the shield from its branch, in such a manner, as to take off with the bark, the smallest portion of the wood, preserving in every case, the green tissue behind the bud. Unless this be attended to, the success of the graft is impossible.
4th—Slip this shield into the incision, between the bark and the wood; then bring the edges of the bark together by means of a ligature, in such a manner, that the base of the bud presses closely to the wood of the stock. This is an essential point.
5th—Sometime after budding, look at the buds, and slacken the bandages if they become too tight.
6th—On the arrival of spring, if the buds have taken effect, cut off the stem or branches of the stock about three inches above the bud. This is done to stimulate the development of the bud.
7th—Cut the head of the subject grafted the following winter. The first or crown grafting, is employed on the large trees from the Esterel to Genes. In Provence, Avignon, and Gard, shield grafting is preferred. At Grasse, they graft the young trees at the age of five or six years, in spring time, when the sap mounts, and when the bark is easily detached. They choose the graft from the gourmand shoots of two years old, the wood well grown and bark smooth; selecting those in which the eyes are well marked. According to the size of the branch, or of the trunk of the tree, they place two scions judiciously. The scions having been placed, the whole is enveloped with clay, and confined with a bandage. The best time is the spring, when the trees are always large and full of branches; some branches are left ungrafted as ducts for the sap, the accumulation of which, at the shoots placed in the crown would be harmful. At Grasse, these branches are called des respirails, and are cut off or grafted the following year.
In Bouche-du-Rhone, shield grafting is the most common; it is now as in the time of Columella, greffe a l'empatre.
Grafting on very young trees, is rarely profitable, not from any difficulty in the process, but because, as the roots require a long time to take hold of the soil, an abnormal disturbance of the sap occurs, and the tree sometimes makes a stunted growth.
The Abbe Jamet says:—"I never graft before the sixth year. At the time of gathering, I accompany the man in charge. I examine the trees, and mark those, of which the shape, the barrenness, or the variety does not suit me. The year following, fifteen or twenty days after flowering, I place two shields upon each of the branches forming the head of the tree. Above the graft, I girdle the branch, and take off the bark. The object of this girdling is to stop the ascending sap, and to bring it to the shoot and facilitate its starting.
The branch above the graft may be left one or two years, according to the vigor of the subject. Its leaves and shade will be beneficial to the graft.
The best time for winter pruning is that which follows frosty weather, and which precedes the first movement of vegetation. By early pruning, the sap is made to act upon the buds unfavorably situated upon the tree, it brings, them out, and also developes latent buds upon the old wood. Thus, by early pruning, it is possible to prevent the tree being covered with naked stems. It may be advantageous to wait even to the period when the shoots begin to lengthen upon trees that possess too much vigor, and which would not otherwise be easily put into a fruit bearing condition.
Grafting in wet weather is to be avoided, as the tree is likely to run, a fine day in spring is the best. The new shoots are not generally touched until the year following the lopping of the branch after the graft has taken. Manured and placed in good earth, the olive requires only three years to form after having been grafted.
The grafts should be taken from that part of the tree which is opposite the mid-day sun. They are chosen from the shoot that would bear fruit the following year.
Those who graft the young tree upon the trunk and not upon the mother branches, take the scions from the shoots which are about to flower.
SUCKERS, KNOTS, LAYERS AND ROOTS.
The knots, or knobs seen on the trunks of olives that have attained any age, are caused by brushing off the suckers that put out on the trunk. The bark forms over the wound made, and a slight excrescence is raised, which persistently sends out further shoots, and the same process being repeated a multitude of times, the final result is a knob, or egg, of varying size. These, cut from the tree and planted at a depth of from four to six inches, give birth to an innumerable quantity of young plants, and is the favorite mode of propagating in certain parts of Italy, having superseded that by cuttings altogether.
The sucker is a developed egg or knob, having germinated while on the tree.
These knobs should be cut from the tree with a sharp instrument and the wound carefully smoothed over and covered with clay or grafting wax. A mixture of cow-dung and clay make a cheap substitute for the latter. But the weight of opinion is against this mode of propagation. The wounds caused the tree are grievous and hard to be borne. They give an opening to the "Lupa" or rot which is ready to attack the olive on the slightest provocation. Only a doomed tree should be dismembered in this way.
The suckers about the root of an olive may be laid down and covered with earth and will give further plants.
The underground portion of the olive tree is composed of two parts, quite distinct, the roots properly so called and which do not shoot of themselves, and the foundations formed of a ligneous mass of tubercles, from which spring the roots in one direction, and the stem in another. Pieces split from this woody mass of the size of the palm of the hand, and an inch and a half thick, planted four inches deep with the back uppermost, will give a great number of young plants. But so will the parent root if left in place. When from any cause whatever, a tree has been marked for destruction, if it is cut off below ground and covered with earth, it will send up quantities of new shoots which may be pulled off as young rooted trees, and their places will be many times supplied with others.
- ↑ Some cloven stakes, and (wond'rous to behold) their sharpened ends in earth their footing place, and the dry poles produce a living race.