Manual of American Grape-Growing. U. P. Hedrick
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.
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.
The stocks are cut into lengths of about ten inches, a gauge being used to secure uniform length. The cut at the bottom is made through a bud in such a way as to leave the diaphragm. The top cut is made as near ten inches from the bottom as possible, leaving about one and one-half inches above the top bud for convenience in grafting. The stock is then disbudded, taking both visible and adventitious buds, the latter indicated by woody enlargements, to keep down the number of suckers.
The cion should be made with but one bud, thereby gaining the advantage of having every cion the same length so that all unions are at the same distance below the surface of the ground in the nursery. The cion is made with about two and one-half inches of internode below the bud and one-half inch above, a sharp knife being the best tool for making the cuts.
Stock and cion cuttings are now graded to exactly the same diameters, this being necessary to secure perfection in the unions. Three methods of uniting stock and cion are illustrated in Fig. 12. It suffices to grade by the eye into three lots—large, small and medium—but some nurserymen prefer to secure even greater accuracy by the use of any one of several mechanical gauges. The methods of uniting stock and cion may be described best by quoting Bioletti, from whom most of the details already given have been summarized:[5]
Tongue grafting.
"When the stocks and scions are prepared and graded the grafter takes a box of stocks and a box of the corresponding size of scions and unites them. Each is cut at the same angle in such a way that when placed together the cut surface of one exactly fits and covers the whole of the cut surface of the other. The length of cut surface should be from three to four times the diameter of the cutting, the shorter cut for the larger sizes and the longer for the thinner. This will correspond to an angle of from 14.5 to 19.5 degrees. The cut should be made with a sliding movement of the knife. This will make the cut more easily and more smoothly.
"The cut should be made with a single quick motion of the knife. If the first cut is not satisfactory, a completely new one should be made. There should be no paring of the cut, as this will make an irregular or wavy surface and prevent the cuttings coming together closely in all parts.
"The tongues are made with a slow, sliding motion of the knife. They are commenced slightly above one-third of the distance from the sharp end of the bevel and cut down until the tongue is just a trifle more than one-third the length of the cut surface. The tongue should be cut, not split. The knife should not follow the grain of the wood, but should be slanted in such a way that the tongue will be about one-half as thick as it would be if made by splitting. Before withdrawing the knife it is bent over in order to open out the tongue. This very much facilitates the placing together of stock and scion.
"The stock and scion are now placed together and, if everything has been done properly, there will be no cut surface visible and the extremity of neither stock nor scion will project over the cut surface of the other. It is much better that the points should not quite reach the bottom of the cut surface than that they should overlap, as the union will be more complete and the scions will be less liable to throw out roots. If the points do overlap, the overlapping portion should be cut off, as in the Champin grafts.
"A skillful grafter, by following the above-described method, will make grafts most of which will hold together very firmly. Many of them would be displaced, however, in subsequent operations, so that it is necessary to tie them. This is done with raffia or waxed string. The only object of the tying is to keep the stock and scion together until they unite by the growth of their own tissues, so that the less material used the better, provided this object is attained. For the formation of healing tissue air is necessary, so that clay, wax, tinfoil or anything that would exclude the air should not be used. The tying material is passed twice around the point of the scion to hold it down firmly, and then with one or two wide spirals it is carried to the point of the stock, which is fastened firmly with two more turns and the end of the string passed under the last turn. The less string is used the more easily it is removed later in the nursery.
"Untreated raffia should be used for late grafts which are to be planted directly out in the nursery, but if the grafts are to be placed first in a callusing bed it is best to bluestone the raffia in order to prevent rotting before the grafts are planted. This is done by steeping the bundles of raffia in a three per cent solution of bluestone for a few hours and then hanging them up to dry. Before using, the raffia should be washed quickly in a stream of water in order to remove the bluestone which has crystallized on the outside and which might corrode the graft.
"Some grafters prefer waxed string for grafting. The string should be strong enough to hold the graft, but thin enough to be broken by hand. No. 18 knitting cotton is a good size. It is waxed by soaking the balls in melted grafting wax for several hours. The string will absorb the wax, and may then be placed on one side until needed. A good wax for this