By W. C. Deming, Connecticut

I do not recall a single modern improvement of importance in the art of grafting nut trees in the North that is not due to either Mr. Jones or Dr. Morris, except that to Mr. Riehl belongs, I believe, the credit of the idea of waxing the entire graft, which is now the accepted procedure. Therefore I speak before these two gentlemen with diffidence. I do so in the hope that perhaps I may recall something which they have forgotten to make known, or that what I say may elicit from them available emendatory remarks. My experience of fourteen years on my own place, and of five years grafting for others, is the basis of my observations.

Compatibility of Species and Varieties

This question will be particularly discussed by Mr. Bixby who has been conducting careful experiments that should soon settle the question for the commoner hickories. A few scattering observations of my own may be useful.

It is generally believed that any species of the genus hickory will catch on any other, though not necessarily that the union will be blessed. It is self evident that any hickory will thrive on any variety of the same species, shagbark on shagbark, pecan on pecan, though even here close observation will probably disclose differences of compatibility. Probably any hybrid hickory will thrive on either of its parents. In some cases this may turn out to be a test of hybridity. For instance, the Barnes is one of the few shagbarks known to thrive on mockernut. It shows other evidences of mockernut blood.

I have found no hickory, so far, that does not appear to thrive on the shagbark, except the pecan. Even here there are differences. I have one Major pecan on shagbark that is over twenty-five feet high that has a very healthy appearance and that has shown staminate bloom for two or three years. I have also an Indian pecan that looks fairly prosperous. The Iowa pecans, the Marquart, Greenbay, Campbell, Witte, and others, catch readily and grow vigorously, at least for the first years. There are many data, however, on the adaptability of the pecan to the shagbark and the consensus of opinion is that ultimate results are poor. This is probably because the shagbark starts early and makes its season's growth in about six weeks, while the pecan naturally has a much longer growing season. However, these observations have been made, mostly, in the South and it may be different in the North. The question is not yet finally decided.

The Stanley shellbark, H. laciniosa, is completely at home on the shagbark, apparently, but has not yet borne with me.

The Hatch bitternut grew luxuriantly on shagbark for a year but blew off.

The Zorn hybrid made a growth of one foot on shagbark but then was winter killed, apparently.

I have a back pasture full of vigorous pignuts, H. glabra, which for eleven years I have been grafting with faith which now seems childlike, that soon I would have fourteen acres of bearing hickory trees. Yet as a result of all these years of grafting the only hickories that I have found to thrive are the Brooks, which appears to be vigorous, the Terpenny, which is vigorous and bearing nuts in its fourth year, and possibly the Barnes. Not a single pecan survived more than a year, though many started. The Beaver hybrid makes a long spindling growth and then, in the first or second year, the leaves turn yellow and mosaic and the growth dies. The Kirtland, Kentucky, Hales, Taylor and several others, have all with me, proved failures on the pignut. Mr. Bixby's experiments appear to be showing somewhat different results.

The question of the compatibility of species and varieties is really a very important one because in some localities either the pignut or the mockernut is the prevailing species, and we wish to know with what species and varieties they may be successfully grafted. For instance, if the Barnes, which is an excellent shagbark, will do well on both the pignut and the mockernut, where so many other varieties fail, and the Brooks is at home on the pignut, these are highly important facts to be known by the man with fifteen acres of hilly woodland full of young pignuts and mockernuts.

Size of Stocks

I prefer stocks of moderate size, up to three inches in diameter. One gets greater results for the labor with these than with larger trees. Of course a tree of any size may be topworked but the labor is disproportionately greater, especially in the after care.

Cutting Back Stocks for Topworking

I doubt if it is important to cut back stocks during the dormant season, except that then there is more time. With larger trees this counts for a good deal, but in the smaller ones I like to cut them off just where I want to graft at the time of doing so. However, they may be cut off when dormant at the point of selection for grafting and later grafted without further cutting back. This reduces, or does away with the risk of bleeding. Except in very small stocks it is better to leave a number of the lower branches to prevent bleeding. When bleeding does occur it may be checked by making one or more cuts with the knife or saw into the sapwood of the trunk below the graft. Better results come when the cutting back is of the top branches and not the lower ones because of the stronger flow of sap toward the top of the tree. In my opinion a side branch should always be left at the point where the stock is cut off to maintain a circulation of sap. Otherwise the stub will often die back and the graft fail. Also, the cambium close to a side branch will be observed to be thicker and I infer that the circulation of sap is more active. I prefer to cut off the top half, or two-thirds of the tree and graft into the top and the side branches near the top.

Hickories in full foliage may usually be cut back without evident harm. Occasionally a tree will be apparently shocked to death. Sometimes when a tree in foliage is cut back severely the remaining leaves will turn black and partly, or completely, die, but the tree will throw out vigorous new growth later.

Trees up to three inches in diameter may have the whole top cut off, at the risk of occasionally shocking a tree to death. Such complete cutting back must be done in the dormant season or there will be severe and prolonged bleeding. This method has the advantage of forcing a tremendous growth in the grafts which will need careful support. This is much more easily done however, than when the grafts are in the top of the tree. Cutting back in the dormant season and painting with paraffine has not worked well for me as the paraffine has not adhered well for any length of time to the freshly cut surfaces. Probably this could be easily remedied if it were a real advantage. In the case of small stocks and branches where there is no bleeding and the paraffine adheres well green callus will often be seen spreading out beneath the paraffine over the cut surface.

Stocks should be vigorous. Dwarfed, stunted, submerged, hide bound trees make poor stocks. This is important, I believe.

Scions

The condition of the scion is the most important element for success in top-working hickory trees. The technique of grafting has been so simplified as to make it fairly easy, and native stocks are usually vigorous. But unless the scions have full vitality success will be limited. They should be plump and not pithy. A limited success is possible with scions of feeble growth, or those subjected to devitalising influences in keeping or handling, but the largest success will be had with well grown scions, cut from vigorous trees or grafts, whose buds are completely dormant, and have a fresh, green appearance on cutting. When the cambium layer shows a yellowish or brownish tint the scions are useless. Slender wood may make good scions but is more difficult to keep in good condition. Heavy wood from vigorous, young, grafted trees, or from cut back trees, makes the best scions and is the easiest to keep. Wood more than 1 year old and as large as one can handle makes good scions. Dr. Morris, with the use of the plane, has succeeded with astonishingly large scions and even branches. Sometimes buds are absent from these large scions or are very inconspicuous. They may be searched for with a lens.

Preferably scions should be cut when entirely dormant. Buds that show signs of breaking should be removed. Scions cut after growth starts may be used with success if there are dormant buds. This "immediate grafting," as Dr. Morris calls it has not been fully studied. It may be of great value. It is quite successful with the apple and the pear. It appears to depend chiefly on the presence of dormant buds of vitality.

The later in the season the dormant scions are cut the shorter the time they have to be kept, though probably this is not of importance if the method of keeping is right.

Keeping Scions

The larger the scion the easier it is to keep it. Dr. Morris cuts whole branches and keeps them in the sawdust of his icehouse. I have cut them two inches in diameter and kept them lying uncovered on the barn cellar floor into the second summer looking fresh and green. The smaller the scion the more susceptible it is to moisture environment. Scions must be kept where it is neither too moist nor too dry. Usually the mistake is made of keeping them too moist. The buds may start if the scions are too moist even when the temperature is quite low. This happened for me when I stored scions for a week or two in the very cold bottom of an icebox. The most successful grafters keep scions with a sort of intelligent neglect. Dr. Morris buries them in the sawdust of his icehouse and it seems to make no difference if ice is there or not. I once tried keeping them in an icehouse over the ice and they became soaking wet. I have noticed that Dr. Morris's sawdust seems quite dry. Mr. Jones keeps some, at least, of his in bins or barrels covered with burlap bags. He says that heartnut scions keep best not packed away but kept in the open cellar. I notice that Mr. Jones has been using some kind of mill planings in place of sphagnum moss. Branches and large scions will keep well in a medium that seems dry to the touch. Small scions, such as those cut from old parent trees, require careful handling to prevent shriveling, on the one hand, or bud starting on the other. A low temperature is probably desirable, but the right condition of moisture is essential to the proper keeping of scions for any length of time. I should naturally prefer to keep them in darkness, but I am not sure that it is important. Undoubtedly the access of some air is necessary but it would be difficult to keep it altogether away. I do not know how long scions would keep if entirely covered with paraffine. One year I dipped all the cut ends of my scions in melted paraffine but I am not sure that it is worth the trouble. One year I packed away my scions in rather moist sphagnum moss. The first time I looked at them they were enmeshed in mold mycelium. Later many of the buds started to grow. As suggested by Mr. Jones, dipping either the scions or the moss in half strength Bordeaux mixture will remedy the mold trouble. Parenthetically, this should be of help in keeping chestnuts, chinkapins, and other nuts that spoil easily with mold, for planting in the spring. Packing scions tightly and heavily covered in boxes for any length of time has been, in my observation, disastrous. In shipping scions a method advised, and one that I have followed with satisfaction, is to wrap the scions, either separately or together, in paraffine paper without any packing next the scions but putting it, instead, outside the paraffine paper. This packing may be sphagnum moss or mill planings slightly moistened. This also is wrapped in a moisture impervious covering and then in ordinary wrapping paper. For shipping long distanced the moss or planings should be dipped in half strength Bordeaux mixture.

The surface of the bark of scions that are being kept should always be dry, never moist. But they should never be so dry as to look shrivelled. Until you know just what scions will do under the conditions you provide you should examine them frequently.

Equipment

The essentials are a knife, raffia and the wax heater with brush. A saw is necessary if stocks are to be cut back, and pruning shears are convenient for cutting scions into proper lengths and for trimming and pruning stocks. The knife most used is the grafting knife of Maher & Gross, with a three inch straight blade and a round handle that gives a good grasp.

I used to suspect that the men who said that scions ought to be cut with two strokes of the knife were trying to establish an unattainable ideal. But after Mr. Jones and Dr. Morris had taught me how to sharpen my knife I found that I could cut one that way myself sometimes. Mr. Jones's method of sharpening is to hone the knife flat on the surface next the scion and with a bevel on the upper edge. I found that this made scion cutting so much easier that I thought it was the whole secret. But one day I saw another doubter come up to Mr. Jones and ask him if it was true that he could cut a scion with two strokes of the knife. Mr. Jones said he thought he could but he had no knife just then. The man pulled out his pocket knife and asked if that would do. Mr. Jones looked at it, took a stick and with two strokes cut a perfect scion. Since then I have felt that there is something to it besides the way you sharpen your knife.

A very important element in shaping scions is to give a drawing motion to the knife by keeping the handle well advanced before the blade. The cutting is done with a draw and not a push. This is one of the most important factors for success in shaping scions.

It seems hardly necessary to say that the stroke of the knife should be away from the grafter. Yet it is a common sight to see beginners cutting to the thumb.

Dr. Morris showed me that if, in sharpening your knife, you hold the little whetstone between the thumb and middle finger of the left hand you are less likely to put a feather edge on it. A feather edge is something to clip the sprouting wings of any budding saint of a grafter. When you get the right edge on your knife often you can use it the whole day without resharpening, or at most with simply a stropping on a piece of wood or leather. But improper use of the knife, or the least knick, will spoil the edge and sometimes it will be quite difficult to get it back. Therefore the blade should always be protected by a sheath, never laid down or used for cutting raffia, or anything but the actual cutting of the graft. For this purpose a leather sheath worn on the front of the belt, as first used by Dr. Morris, is almost a necessity. This sheath may be made by any leather worker and should have at least two pockets, one for the grafting knife and one for another knife to be used for trimming, cutting raffia and other odd things. It is convenient to have a little pocket for a pencil also and one may provide places for other articles of equipment at fancy.

I do not know that there is much to be said here about raffia. But a great deal has been said, and will be said, elsewhere, when the raffia is rotten and breaks in the middle of tying a graft. It is the devil's own stuff to carry when you don't carry it right. The right way to carry it is to tuck one end of the bundle under one side of your belt, pass the bundle behind your back and the other end under the other side of your belt. Then the raffia never gets mixed up with scions, tools and profanity and the end of a strand is as handy as the knives in your belt. On the whole I do not know of any binding material as satisfactory as raffia. It is stronger and easier to use when it is damp.

One of the great advances in the art of grafting is the use of melted wax. I believe that we have to credit Mr. Jones for this. The use of paraffine for grafting wax we owe to Dr. Morris. To him also we owe the Merribrook melter which has added so much to the comfort and convenience of grafting that it can be recommended as an outdoor sport for ladies. I do not like the brush that Dr. Morris recommends but prefer a stiffer one such as can be bought for ten cents.

Equipments vary with the individual and with the difference in the work to be done. Mr. Slaughter carries into the nursery, when he is working for Mr. Jones in the semi-tropical sun of Lancaster, a stool with parasol attachment. Mr. Biederman of Arizona has the most elaborate equipment which includes a table, planes, curved knives and gouges. Dr. Morris carries a knapsack. I like an ordinary light market basket that Mother Earth holds up for me when I'm not moving from place to place. When in a tree I stuff my pockets with scions.

A saw is usually a necessity. For portability I prefer a curved one that has a draw cut. It has also an aesthetic element and doesn't look like a meat saw, which can't be said of Mr. Jones's saw that seduced Dr. Morris from church. For heavy and steady work I much prefer a carpenter's sharp hand saw. A two-edged saw is an abomination devised by conscienceless manufacturers for the seduction of innocent amateurs.

For pruning shears I have a personal fancy for the French, hand-made instrument, each one individual, a work of art and a potential legacy to one's horticultural heir, if one doesn't let the village blacksmith monkey with it, as I did with mine.

On some grafts it is desirable to use a bit of paper, either beneath or outside of the raffia, to make waxing easier. For this I have found scraps of Japanese paper napkin very adaptive to surfaces and absorptive of wax.

On very heavy grafts Dr. Morris uses the Spanish windlass, as devised by him, for which he carries sisal cord, wooden or metal meat skewers, small staples and a mallet. He uses a chisel to cut slots in very thick bark and planes for shaping heavy grafts.

I have tried fastening in grafts with a nail, using iron and brass nails and bank pins. Mr. Jones has suggested cement covered nails. My experience with iron nails is that they damage the scions. The use of nails has not been fully worked out. They are almost essential in bridge grafting apple trees. I think that just the right kind of a staple might be a help with some kinds of grafts.

Paper bags, 2 pound size, are sometimes wanted, for protection from sun or insects or to make the grafts conspicuous. Mr. Jones shades grafts made close to the ground with a slip of paper.

For labels for immediate use the wooden ones, painted on one side and with copper wire fastening, are satisfactory. Attach them by the nurseryman's method, which it has taken me many years to recognize as the right one, by twisting the doubled wire around a convenient object. Do not separate the wires which will probably permit the label to flap in the wind and soon wear out the wires. I used to think that the nurseryman's method was the result of hurry or laziness.

Copper labels, to be written on with a stylus, cost 1-1/2 or 2 cents each, according to size. The smaller I consider preferable. I imagined that these would solve the label problem. Picture my disappointment when I found that many of them cracked, or broke off entirely near the eyelet, from flapping in the wind. If they are to be used they must be fastened so as not to move with the wind. Mr. Bixby has an excellent label made on an aluminum strip printing machine. It has a hole in each end and is fastened with a heavy copper wire. He uses two of these labels on each tree. Dr. Morris sometimes uses a heavy wire stake to which he fastens the labels. A good method of attaching labels, and one that does away with the risk of girdling the graft or tree, is to fasten the label to a staple driven into the tree. The matter of labels is a troublesome one for they will get lost no matter what you do.

Other conveniences of equipment are a small whetstone, a small hammer, matches, and some volatile oil, like citronella, lavender, wintergreen, or other black fly and mosquito repellant. It is almost suicidal to slap a mosquito on the back of your neck with a keen grafting knife in your hand. A supply of parowax and alcohol for the lantern's sake should be remembered.

Technique

If the stocks are vigorous and active, and the scions full of vitality, I doubt if the technique is of chief importance, provided it is ordinarily good. However, a good technique will increase the percentage of success. One should have a variety of methods at command for varying conditions of stocks and scions.

One may come as near 100% success in grafting hickories as one is able and willing to observe all the known factors of success. I think that we can say now that the factors of success in hickory grafting are known. They are a vigorous and active stock, a scion of abundant vitality, coaptation of the freshly cut cambium layers and prevention of desiccation.

The stock and scion have already been considered. How is coadaptation best obtained? One of the best methods, one that can be used in all seasons and in most conditions of stock and scion, is the side graft, the one that Mr. Jones uses in his nursery work. That is the best argument for this graft. It is, perhaps, the simplest, and at the same time one of the most difficult, of all grafts. The scion is cut wedge shaped and pushed into a slanting incision in the side of the stock. Mr. Jones's modified cleft graft is only a side graft made in the top of the stock after cutting it off. The difficulty lies chiefly in cutting the scion and the incision in the stock so that the fit will be perfectly true. This requires practice.

The bark slot graft, as Dr. Morris calls it, I have used for several years. It can be used only during the growing season when the bark will slip. It is very successful, whether put in at the top of a cut off stock, or inserted in the side of a limb or the trunk. It is not convenient to use unless the scion is considerably smaller than the stock. The scion is cut with a scarf, or bevel, on one side only. When the slot is to be made in the top of a cut off stock two vertical cuts are made through the bark, as far apart as the scion is wide, the tongue of bark thus formed is raised slightly at the top, and the point of the scion is inserted, cut surface toward the center of the tree, and pushed down firmly into place. The superfluous part of the tongue of bark is then cut off. By slightly undercutting the edges of the slot, and slightly tapering it toward the bottom, the scion may be wedged, or dovetailed, in place so as to be very firm. It is even possible to dispense with tying, sometimes, but better not to do so.

When the slot is to be made in the side of a limb or trunk the same procedure is followed except that it is necessary before making the slot to remove a notch of bark, at right angles to the axis of the trunk, so as to free the upper end of the tongue of bark.

The bark slot graft is the easiest of all and readily mastered once the grafter learns to shape a true scion. It is much better than the old bark graft where the bark of the stock is forced away from the wood leaving considerable space to be filled or covered.

These two forms of graft, the side graft, of which Mr. Jones's modified cleft graft is only a variation, as before stated, and the bark slot, in its two variations as described, will meet all needs in topworking hickory trees.

Finally, prevention of desiccation of the graft is obtained by waxing. I have found Dr. Morris's method with melted paraffine satisfactory. The addition of raw pine gum, as advocated by Dr. Morris is undoubtedly an advantage under certain conditions, described by him, but I have not yet used it. The melted parowax is applied to the whole graft and wrapping, leaving no cut surface exposed and the whole scion being covered. If the paraffine is at just the right temperature it will spread at a touch, covering the surfaces without danger of scalding. It is much more effective thus applied than if colder and daubed on. The thicker the waxing the more likely to crack and separate. If the paraffine smokes it is too hot. If it does not smoke, and is dexterously applied, I think we can feel safely that it cannot be too hot. But if applied with a heavy hand it may be too hot even at a temperature so low that it will not spread.

Season for Grafting

According to Dr. Morris nut trees can be grafted successfully in any month of the year. But practically I think that grafting will be limited to that part of the year during which the cambium layer of the stock is active. At other times of the year preservation of the vitality of the scion will be too problematical, it seems to me, even if it is very carefully waxed. However, I may be mistaken. At any rate grafting is not very pleasant work out of doors in very cold weather. The success of bench grafting would be an argument for the success of dormant season grafting out of doors.

After Care

Without thoughtful after care the labor of topworking will almost certainly be lost. There are many ways in which the grafts can be lost but the two commonest are by being choked, or inhibited, by growth from the stock, and by being blown out by the wind. All new growth from the stock must be rigorously prevented. Grafts often make so heavy a growth that, if not blown out by the wind, they will be dragged out by their own weight. Consequently they must often be supported. When the grafts are in, or near, the trunk of the stock, and not too high, the handiest method of support is to cut a sapling of proper length, sharpen the butt, stick this into the ground at the base of the stock, and tie it in two places to the stock. When the grafts are too far out or too high for this method laths or slats or sticks may be tied or nailed to the branches. Support is likely to be even more necessary in the second season when the growth is often astonishing.

Bud worms will sometimes destroy your graft just as it is starting, but they are easily found if looked for. With my conditions the most harm by insects is done by the night feeding beetles, which are particularly exasperating as morning after morning you watch the progress of their destructive work without ever seeing them. Bagging is the only preventive and it pays to use bags when a particular graft is cherished.

Is Topworking Hickories Worth While?

Up to the present time it is the surest and easiest way, practically the only way, of getting good results with the hickories, excepting the pecan. The root systems of the native stocks are well established and push the grafts rapidly. I have had a Siers hybrid grow 11 feet Straight up in a season. A Taylor matured several nuts on the third season's growth. A Terpenny had a crop the fourth year, the Griffin bears annually since its fifth year, the Kirtland and Barnes since the sixth. The Kentucky is a little slower. None of the hybrids have yet borne with me but with others they have borne quite early. We can be sure that the hickories will bear when top worked as soon as the average apple tree. The size of the crop that any topworked hickory tree will bear will depend on the size to which you have been able to grow the tree and the habit of bearing of the particular variety. I think, also, that there is good evidence to show that the size of the tree, the size of the nuts and the size of the crop will depend largely on the amount of care and the amount of plant food that is given the tree.

Two years ago I topworked a number of hickory trees for Mr. Patterson of Wilkes-Barre, one of our members, and Mr. Patterson's foreman put in a few grafts under my observation. This summer I went to Wilkes-Barre to inspect my work. The foreman took me out into a field where he had done a lot of grafting the year before and I found that he had had a little better percentage of success than I had had. He had used the bark slot graft for everything, even when the scions were almost as big as the stocks. Before this I had thought that long experience was necessary for successful grafting. Now I see that if you have good scions, a Morris melter and a half hour of instructions, you will have all the essentials for immediate success. Hickory grafting is easy now. But let no one be contemptuous, for this ease has come only after many years of experiment and countless failures by many men. The former difficulty in grafting the hickory seems now like a mystery. The history of its evolution would make a very pretty story for the nut grower.