THE BENCH ROOT-GRAFTING OF PERSIAN WALNUTS AND PECANS.

By C. P. Close, U. S. Dept, of Agriculture, Washington, D. C.

The results of my bench root-grafting of Persian walnuts and pecans at the Maryland Agricultural Experiment Station in 1911 were not as satisfactory as might be wished, partly owing, at least, to the unusually long and hot drought which was disastrous in many respects in this section of the country.

PURPOSE AND METHOD OF THE EXPERIMENT.

The purpose of this experimental work was to devise some method of procedure in the bench grafting of nut trees which would be reliable and practical, especially if done during January, February, and March. The whip or tongue method with variation in thinness of tongue to make closely fitting unions, was employed. For the Persian walnut cions, black walnut, butternut and Persian walnut roots were used, and for the pecan cions, hardy Indiana and ordinary southern pecan seedlings, whole root and piece root, were used. Part of the grafts were planted outdoors in nursery rows as soon as made and part were placed in soil or decayed sawdust in a cool greenhouse. This was for the purpose of determining whether or not it would prove advantageous to go to the extra expense and trouble of placing the grafts under greenhouse conditions until April or May. Ground beds were used and thus bottom heat was not applied.

PERSIAN WALNUTS.

There were 287 grafts of San Jose, Concord and Franquette Persian walnuts, made from February 15 to April 4, which were planted in nursery rows very soon after being made. Only 40 of these were alive in October, the best results being obtained with San Jose on black walnut stocks. Sixty-four walnut grafts were placed in decayed sawdust in the greenhouse in February and March and of these 22 were alive early in May when they were taken out.

PECANS.

The pecan grafts, set in nursery rows as soon as made, numbered 474 and consisted of the following varieties: Mantura, Appomattox, Frotscher, Moneymaker, Van Deman, Stuart, and Pabst. Only one of these, a Pabst on a piece root, lived during the season.

The grafts which were placed in the greenhouse gave pretty good results as shown by the following data given respectively under the headings "Earth Bed" and "Decayed Sawdust."

EARTH BED.

Jan. 14. 10 Moneymaker on Indiana stocks, not waxed. 8 alive in May.

10 Moneymaker on Indiana stocks, waxed 4 alive in May.

Feb. 14. 10 Mantura on Indiana stocks, not waxed. 8 alive in May.

15 Moneymaker on Indiana stocks, not waxed.11 alive in May.

Mar. 8. 33 Stuart on Indiana stocks, not waxed.20 alive in May.

30 Stuart on Indiana piece roots, not waxed.15 alive in May.

——

Totals10866

DECAYED SAWDUST.

Feb. 14.25 Mantura on Indiana stocks, not waxed.6 alive in May.

Mar. 8.12 Stuart on Indiana stocks, not waxed.12 alive in May.

23 Stuart on Indiana stocks, not waxed.21 alive in May.

——

Totals6039

These figures show that 61 per cent of those in the earth bed and 65 per cent of those in the decayed sawdust, were alive when they were taken up early in May. Some had made a growth of from two to eight inches and were fine little trees. Most of these transplanted grafts were set in nursery rows and nearly all succumbed to the extreme drought of the season.

CONCLUSIONS.

The season was so extremely dry that the practice of planting root grafts as soon as made did not prove successful. However, work done in other years indicated that in normal seasons this may be done with considerable success. Placing the grafts in a greenhouse either in earth or decayed sawdust gave encouraging results, but when transplanted in the nursery the grafts could not withstand the unusually dry and hot weather. The black walnut proved to be the best stock for the Persian walnut and two buds to the cion are required. Grafting wax should not be used if the union of cion and stock is to be covered with earth; this point was clearly proven in previous years.

[The foregoing paper, read by title, was the subject of a verbal report by Prof. Lake, who said further:]

Prof. Close performed considerable work in topgrafting and budding on three and four year old stocks. The top grafts were a failure. The buds survived, and were in good, strong condition October fifteenth. That was on Persian walnut and pecan, about half and half.

Mr. Pomeroy: Did he bud on black walnut stock?

Professor Lake: Yes. It was a little higher than a man, and had been cut back to about three feet. The crown grafting was fairly successful, but would have been much more successful, had they used something to cover the grafts.

Mr. Pomeroy: How long should the paper sack be left?

Professor Lake: It would vary with the season and activity of the stock, ten days to two weeks.

President Morris: I wish you would try further experiments in rooting scions in warm sand in the hot-house. I believe that in some stage you can probably root those cuttings in moist sand in the hot-house, heated beneath; and if you can do that, it is going to settle the question very largely of hickory and walnut propagation. What do you think about that, Professor Craig?

Professor Craig: I am not very optimistic about the possibility of that. I find it very, very difficult to get roots to develop from Hicoria. You can get the callus almost every time, but it is very difficult to secure the development of roots afterwards.

President Morris: How about getting callus by three months, we will say, in storage?

Professor Craig: We would have the same trouble. They would develop adventitious buds very poorly. Doctor Morris has sent us from time to time some samples, and we have been making experiments. I have used different methods and different propagators. We have one propagator, who has been most successful usually in striking difficult things, and he has absolutely failed in this one. I may say that our facilities for propagation are not ideal at the present time, but we shall have in a short time a good propagating house with properly regulated benches, as to bottom heat and overhead ventilation and all that; and we shall, of course, keep up the experiments.

President Morris: In my experiments, I grafted hickory scions on hickory roots, and the whole thing, root and scion, lived until the root sent out adventitious buds, yet in that case we did not get union between the top and the stock. How do you explain that, Professor Craig?

Professor Craig: I don't explain it.

President Morris: Are we likely to have success along that line by some modification of the plan?

Professor Craig: I couldn't say. You can keep the cuttings alive for three or four months.

President Morris: They were in damp rooms, exposed to light, right in the window.

Doctor Deming: Professor Coville has made some experiments in rooting hickory cuttings for me. Professor Coville is the one who has made such a success of blueberry culture. I sent him some cuttings, and he reports as follows:

"Two experiments were tried with the hickory cuttings received from Dr. W. C. Deming on January 5, 1911. In one experiment some of the cuttings were placed in a glass cutting bed in live sphagnum covered with sand, the upper ends of the cuttings projecting from the sand. The atmosphere above the cutting bed was kept in a state of saturation by a covering of glass. The bed was kept shaded and was subjected to an ordinary living room temperature varying from about 55° to 70°, or occasionally a few degrees higher.

On January 11 the cambium ring at the lower end of the cuttings had begun to callus. On February 17 the upper bud on one of the cuttings began to push. Later some of the other cuttings began to swell preparatory to the development of new growth. All the cuttings, however, finally died. It appeared from their behavior that the temperatures to which they were subjected were too high for their best development.

In the other experiment the cuttings were placed in sand without sphagnum in a greenhouse at a temperature ordinarily of 50° to 65°, rising occasionally, however, on still, sunny days to 70°. After a few weeks, these cuttings were well callused and the buds began to swell slowly, exposing first their green bracts, and later on some of the cuttings the green compound leaves, pushing out from among the bracts. These cuttings also, however, finally turned black and died, but not until after the first of April.

The experiments showed that hickory cuttings, when taken at a suitable time of year and exposed to conditions suited to other hard wooded plants known to be difficult to root, retained their vitality and passed satisfactorily through the stages preliminary to rooting. While no actual roots were secured, the experiments suggest that the rooting of hickory cuttings is not beyond the possibility of attainment.

As the basis of an experiment this winter, I suggest that you select half a dozen twigs that you are willing to sacrifice on some good variety of hickory, and remove a ring of bark at a distance of 4 to 8 inches from the top. The ring of bark removed should be about half an inch in length and its upper end should come about a quarter of an inch below a bud. At the present season the bark will not peel from the wood. It will, therefore, be necessary to scrape it off, so as to leave nothing but the wood on the girdled area. The bark should be cleanly cut at each end of this area. I hope that we shall still have sufficient warm weather to induce the formation of a callus on the cambium at the upper end of this ring.

Later in the winter, some time in January, you can cut off these twigs and send them to me, packed as those were last year. The cutting is preferably made just below the ring. I would prefer that all the wood from the ring to the tip of the twig be of the past summer's growth. We can try, however, twigs containing two seasons' growth, if the others are not easily available."

President Morris: That is a suggestion, you see, of apparent value, because it has succeeded with blueberries,—this method of cutting off a ring of bark before the leaves are shed, allowing a ring to callous, then later cutting off this prepared twig and subjecting it to methods for striking roots. It is an extremely interesting suggestion. Just as soon as I heard of this procedure, I went out and prepared about fifty hickory and walnut twigs myself, but that was this autumn, and I haven't cut them yet for the experiments in rooting. Has anyone had experience along this line?

Mr. Collins: I saw an experiment in rooting, and I am prompted to ask if anything has been done along this particular line. The method employed was this. The twig was partially cut from the branch, perhaps cut three-quarters of the way through with a slanting cut. It was then bent a little, and a little sphagnum put in the cut, then a ball of sphagnum was wrapped about the whole cut area, and it was tied with twine, and that was kept wet for several months, I think, until, finally, new roots pushed through and appeared on the outside of this ball of sphagnum.

President Morris: I read of that. It was published in a government report.

Professor Collins: It was on the rubber plant.

President Morris: I tried it at that time on the hickory. The difficulty was in getting my men sufficiently interested to keep the sphagnum wet all the time. It promised something. The rubber plants, perhaps, would lend themselves more readily to such a procedure than the hickories, because most of the rubber plants are air plants, anyway. All of the Ficus family depend so little upon the ground for their nourishment.

Professor Collins: I have seen that worked very successfully.

Professor Lake: You don't know how successful the callousing has been?

President Morris: They calloused all right.

Professor Lake: How long did it require?

President Morris: I don't remember. It was a good while, longer than I anticipated. I don't think there was a callus on the hickory in less than thirty days. The butternut and black walnut hardly showed any callus at all after keeping the sphagnum wet as long as my men would do it.

Professor Lake: At what time was the ringing done?

President Morris: The leaves had fallen this year. Professor Coville suggested that it be done before the leaves had fallen. But the hickory will callous after the leaves have fallen. It seems to me hickories are at work all winter long. They have a free flow of sap in January, and any warm day in January they will be like a maple tree, almost, if they are cut. I have grafted them at that time.

Mr. Brown: Can anyone give me any information on grafting chestnuts?

Mr. Rush: I have been very successful with the grafting of the chestnut. It is just as simple as grafting other fruit, except the Persian walnut. Tongue grafting and cleft grafting is very successful. There is no particular secret in connection with grafting chestnuts.

President Morris: Personally, I found it difficult for two or three years, but now I can graft the chestnut about as readily as I can graft the apple. There is no difference in methods. It seems to me from my present experience that one may graft or bud chestnut by almost any of the accepted methods pretty freely. What has been your experience, Mr. Littlepage?

Mr. Littlepage: I haven't been experimenting with the propagation of the chestnut yet. I am getting ready. I have three or four thousand seedlings, a few of which will be ready to graft next year. I have twenty acres of the Paragon chestnuts growing.

President Morris: In chestnut grafting, we will find that one kind does not graft or bud readily upon another kind, perhaps. For instance, there is some antagonism between the American sweet chestnut and Asiatic chestnuts. There is some antagonism between Asiatic and Europeans; there is little between Europeans and American sweet. These antagonisms are something that one has to learn from experience at the present time, because I doubt if we have had enough experience to know just where we stand on this question.

Professor Collins: Doesn't there seem to be antagonism between eastern Asiatic other than Japanese and Japanese?

President Morris: Yes; the Koreans of both kinds, the north Japanese of both kinds, and the Manchurian chestnut are the five that I have experimented with in grafting, and none of those grow so well on American stock as they should.

Professor Collins: I mean to say between the Korean and the Japanese.

President Morris: There is less antagonism. You can graft the Korean upon the Japanese and the Japanese upon the Korean very readily. They have very much the same texture of wood, the same character of buds and bark.

Professor Collins: Is there any antagonism between eastern Asian and Japanese?

President Morris: I don't know that my experience has been extensive enough to say. My men have put on perhaps two or three hundred grafts back and forth between these kinds, the customary accidents have happened, and we have about given up trying to do much grafting of Japanese on American, but still plan to graft Japanese back and forth upon each other, and we are now planning to graft European and American back and forth upon each other.

Mr. Brown: What about the position of the graft?

President Morris: I don't know, Mr. Brown, if there is very much difference. I haven't found very much. I have grafted all the way from the root to the top.

Mr. Rush: It is better on top. Sometimes the grafting has an effect upon the stock just at the union. If it is budded low, it blights. The bark gets loose. All those that are grafted high are doing remarkably well.

President Morris: The next on the list is Doctor Deming's paper on "Nut Promotions."

Doctor Deming: I will read first a communication from Mr. Henry Hales of Ridgewood, New Jersey.