Part 4 (1/2)
[Ill.u.s.tration: FIG. 8. Cutting off the trunk.]
In eastern America, the growing vine is usually grafted. At the New York Agricultural Experiment Station, the operation is very successfully performed on old vines as follows: Preparatory to grafting, the earth is removed from around the stock to a depth of two or three inches. The vines are then decapitated at the surface of the ground and at right angles with the axis of the stock. If the grain is straight, the cleft can be made by splitting with a chisel, but more often it will have to be done with a thin-bladed saw through the center of the stock for at least two inches. The cion is cut with two buds, the wedge being started at the lower bud. The cleft in the stock is then opened, and the cion inserted so that the cambium of stock and cion are in intimate contact. If the stock is large, two cions are used. The several operations in grafting are shown in Figs. 8, 9, 10 and 11. Grafting wax is unnecessary, in fact is often worse than useless, and if the stock is large the graft is not even tied. Raffia is used to tie the graft in young vines. It suffices to mound the graft to the top of the cion with earth, for the purposes of protection and to keep the graft moist. Two or three times during the summer, sprouts coming from the stock or roots from the cion should be removed.
[Ill.u.s.tration: FIG. 9. Cutting the cleft.]
A method used with fair success at the New York Agricultural Experiment Station with young vines is to plant one-year-old stocks in the nursery row as soon as the ground can be worked in the spring.
Just as the vines start in growth, these are cut off at the surface of the ground and whip- or cleft-grafted with a two-eye cion. The graft is tied with raffia, after which it is all but covered with a mound of soil. This is a case in which the work must be done at the accepted time, as it is fatal to delay.
[Ill.u.s.tration: FIG. 10. Inserting the cion.]
[Ill.u.s.tration: FIG. 11. The completed graft.]
R. D. Anthony describes another method as follows:[2] ”A method which a Pennsylvania grower of Viniferas has found very satisfactory is to root the Vinifera cuttings, and grow them one year on their own roots; then the vine which is to be used as a stock is planted in the vineyard and the rooted cutting planted beside it so that the shoots from the two may be brought in contact with each other. In June when the plants are in full growth, two vigorous shoots (one from each vine) are brought together and a cut two or three inches long made in each parallel to the length of the cane removing from one-third to one-half of the thickness of the shoot. These flat surfaces exposed by the cuts are then brought into contact with the cambium tissues touching and are tied in place. The tops are checked somewhat by breaking off some of the growth. The following spring the Vinifera roots are cut off below the graft and the top of the stock above the graft is removed.”
In the subsequent care of these young vines, the grower must take time by the forelock and tie the grafts to suitable stakes; otherwise they are liable to be broken off at the union by wind or careless workmen.
Grafted vineyards must have extra good care in all cultural operations, and even with the best of care from 5 to 50 per cent of the grafts will fail or grow so poorly as to make regrafting necessary, this being the most unfavorable circ.u.mstance of field grafting. Regrafting is done one joint lower than the first operation to avoid dead wood; this brings the union below the surface of the ground, and the vineyardist must expect many cion roots to try his patience.
_Vineyard grafting on the Pacific slope._
Vineyard grafting, according to Bioletti,[3] was formerly the commonest method of starting resistant vineyards in California. After stating that it is best whenever possible to plant good cuttings rather than roots, and that the grafting should usually be done the year after planting, Bioletti gives the following directions for grafting:[4]
”Wherever possible the vines should be grafted at or above the surface of the ground. In many cases, however, it will be necessary to go below the surface to find a smooth, suitable part of the stock where grafting is possible.
”The kind of graft to use will depend on the size of the stock. For stocks up to 2/3 inch in diameter the methods of tongue and wire grafting already described are the best. For larger vines up to 3/4 inch a modification of the ordinary tongue graft is the best. If the tongue graft were made in the usual way with stocks of this size, it would be necessary to use excessively large scions, which is undesirable, or to have the barks unite only on one side. By cutting the bevel of the stock only part way through the vines, it is possible to make a smaller scion unite on both sides. For still larger vines, those over 3/4 inch in diameter, the best graft is the ordinary cleft.
”No wax or clay should be used on the graft. Anything which completely excludes the air prevents the knitting of the tissues. A little clay, cloth, or a leaf may be placed over the split in the stock when the cleft graft is used, simply to keep out the soil. Otherwise there is nothing more suitable or more favorable to the formation of a good union that can be put around the graft than loose, moist soil. If the soil is clayey, stiff or lumpy, it is necessary to surround the union with loose soil or sand brought from outside the vineyard.
”It will usually be necessary to tie the grafts. A well-made cleft graft often holds the scion with sufficient force to prevent its displacement and no tying is necessary. Wherever there is any danger of the graft moving, however, it should be tied. There is nothing better for this purpose than ordinary raffia. The raffia should not be bluestoned, as it will last long enough without and will be sure to rot in a few weeks, and the trouble of cutting it will be avoided.
Cotton string or anything which will keep the graft in place for a few weeks may also be used.
”As soon as the graft is made and tied, a stake should be driven and the union covered with a little earth. The hilling up of the graft may be left for a few hours, except in very hot, dry weather. Finally, the whole graft should be covered with a broad hill of loose soil 2 inches above the top of the scion.
”Field grafting should not be commenced as a rule, except in the hottest and driest localities, before the middle of March. Before that there is too much danger that heavy rains may keep the soil soaked for several weeks--a condition very unfavorable to the formation of good unions. In any case the grafting should not be done while the soil is wet. Grafting may continue as long as the cuttings can be kept dormant. It is difficult to graft successfully, however, when the bark of the stock becomes loose, as it does soon after the middle of April in most localities.”
As in the East, it is necessary in California to remove suckers from the roots and roots from the cions once or twice during the summer.
Suckers should not be allowed to overshade the graft, though it is best not to remove them until danger of disturbing the graft is past.
The grafts should be staked and the vines looked after as recommended for eastern conditions.
[Ill.u.s.tration: PLATE III.--Cover-crops. _Top_, cow-horn turnips; _bottom_, rye.]
_Bench grafting._
The resistant vineyards of France and California are now started almost entirely with bench-grafted vines. It has been learned in these regions that a grafted vine, to be a permanent success, must have the consorting parts perfectly united, and that the sooner the grafting is done in the life of stock and cion the better the union. Cions of the variety wanted are, therefore, grafted on resistant roots or resistant cuttings in the workshop and then planted in the nursery. Bench grafting has the advantage over field grafting in time gained and in securing a fuller stand of vines.
Bench grafting really begins with the selection of cuttings, since success largely depends on good cuttings of both stock and cion.
Cuttings are taken from strong healthy vines and are of medium size, with short to medium joints. The best size is one-third of an inch in diameter, that of stock and cion being the same since the two must match exactly. The cutting-wood may be taken from the mother vines at any time during the dormant season up to two weeks before buds swell in the spring, and the cuttings can then be made as convenience dictates, though meanwhile the wood must be kept cool and moist, which is best done by covering them with moist but not wet soil or sand in a cellar or cool shed. In California, the best results are obtained when the grafting is done in February or March, though it may be begun earlier and continued a month later.
_Preparation of cuttings._