Northern Nut Growers Association Report of the Proceedings at the Fifteenth Annual Meeting / New York City, September 3, 4 and 5, 1924

by Unknown

NOTES ON MEDIATE AND IMMEDIATE GRAFTING AT ALL TIMES OF THE YEAR

By Dr. R. T. Morris, Connecticut

Any newly described fact which releases information on the subject of tree grafting opens vistas of the new frontier in world agriculture.

Time was when men went from one country to another in search of fresh top soil. That was when they did not know better. It was when their cogs of habit turned their cogs of thought. They were engaged in raising annual plants at a considerable expenditure of time, labor and expense. They committed wastage of soluble plant foods (a variety of sin).

Malthus formulated a famous over-population fear-thought. It had basis in his ignorance of the fact that steam was soon to become a factor in the spreading of food supplies. Furthermore, he seemingly did not know that when old top-soil frontiers had gone to the rear, new frontiers would appear in the sub-soil. The tree digs deeper than the farmer ever plowed.

After Malthus came hunger prophets who were ignorant of coming possibilities of fleet transportation through the air. The caterpillar tractor plunging into the tropical jungle will allow of the production of a practically unlimited food supply. Famine in India, China, and Russia is a social matter and unnecessary. Trees cure famine.

Within the past decade a number of thinkers on one end of the see-saw have written heavily on the over-population question not knowing that they and their birth control ideas were to be tossed into the air by still heavier weight of fact on the other end of the see-saw.

The heavier weight of fact relates to the idea that famine does not belong to tree food regions. It relates to the fact that tree foods can supply all of the essentials of provender for men, livestock and fowls; proteins, starches, fats and vitamines in delicious form. It relates to the fact that tree foods come largely out of the sub-soil without apparent diminution of fertility of the ground. The tree allows top-soil bacteria and surface annual plants to manufacture plant food materials and then deep roots take these materials to the leaves for elaboration by sun chemistry.

Trees may be grown wherever crops of annual plants may be grown and where annual plants may not be grown profitably. They do not require the service of high cost labor for annual tillage of the soil. For example, four large pecan trees or black walnut trees on an acre of ground without tillage or fertilizer may average a thousand pounds of nut meats annually for a century. How often is the market value and food value of a thousand pounds of nut meats per acre equalled by crops from annual plants which would require from 100 to 200 plowings and harrowings during a hundred years of continuous cultivation leaving out the question of expensive fertilizers and labor. Large populations live upon dates, olives and figs. For trouble they have to look to religion.

Several centuries were required for the British farmers to raise the wheat crop from six bushels to thirty bushels per acre. Things move faster nowadays. It will not require so long a time to carry tree crops from the seedling phase to the phase of grafted kinds with greater productivity and quality. In the past the successful tree grafter was a specially skilled man. Now almost anybody may graft almost any sort of tree at almost any time of the year.

Aside from grafting, the hybridizing of nut trees, like that of cereal grain plants, has become a scientific sport appealing to the play instinct of man. When work becomes play in any field of human activity progress goes by leaps and bounds. The recent advance in tree grafting has amounted almost to a revolution rather than an evolution process. Application of a few new grafting principles of great consequence is now the order of the day. Old established grafting methods frequently ran into failures when dealing with all but a few trees like the common fruit bearing kinds.

The two chief obstacles to successful grafting were desiccation of the graft and fungous or bacterial parasites which entered the land of milk and honey where sap collected in graft wounds. Both of these dangers have now been practically eliminated and it remains for us to extend the season of grafting, carrying it away from a hurried procedure in busy spring weeks.

The chief obstacle to this extension of the grafting season has been the difficulty in finding the right sort of grafting wax or protective material for covering the graft, buds and all, as well as the wound of the stock. For covering the entire graft in order to avoid desiccation grafting waxes had to be applied in melted form with a brush. They had to be applied in melted form for filling interstices of wounds in which sap might collect and ferment. These waxes had the effect of not retaining their quality under greatly varying conditions of heat, cold and moisture. The paraffin waxes which the author has preferred were inclined to crack and to become separated from the graft and stock in cold weather. Furthermore they would remelt and become useless in the very hot sun of southern latitudes.

Experimentation for several seasons has resulted in the finding that raw pine gum is miscible with the paraffins in almost all proportions because of physical or chemical affinity. This gives to the wax an elasticity and adhesiveness of such degree that we may now graft trees in cold weather. Cohesiveness of molecules of the mixture is such that remelting in the hot sun may not destroy the effectiveness of this protective coating in hot weather.

Since the author has depended upon this mixture he has grafted peaches, apples, hazels and hickories successfully in midwinter as well as in midsummer. Many other kinds of trees have been grafted successfully out of the so-called grafting season but these four kinds which represent two of the "easiest grafters" and two of the "hardest grafters" will suffice for purposes of illustration.

According to old-established idea trees may be grafted successfully only from scions that have been cut when dormant and stored in proper receptacles. This is what we may term "mediate grafting," a considerable length of time intervening between cutting the scions and inserting the grafts. On the other hand what we may call "immediate grafting" is the taking of a scion from one tree and grafting it at once in a tree that is to receive it. Mediate or immediate grafting may both be done at almost any time of the year, winter or summer, spring or autumn.

When preparing the scion for immediate grafting in the spring or early summer it is best to cut off all the leaves and herbaceous growth of the year. We then depend upon latent buds situated in the older wood of the scion. The latter may be one year or several years of age.

In midsummer when top buds have formed we may remove only the leaves, allowing the growth of the year to remain and to serve for grafting material.

In experiments with the apple for example it was found that mediate grafts inserted on July 10th in the latitude of Stamford, Conn., began to burst their buds five or six days later. Immediate grafts inserted at the same time began to burst their buds about fifteen days later from buds of the year and about twenty days later from latent buds in older scion wood.

New shoots from these mediate apple grafts continued to grow as they do in Spring grafting. Immediate apple grafts on the other hand put out about six leaves from each bud and then came to a state of rest with the formation of a new top bud. After about ten days of resting these new top buds again burst forth and grew shoots like those of the mediate grafts.

The philosophy of these phenomena would seem to include the idea that the mediate summer grafts had contained a full supply of pabulum stored up in the cambium layer. The immediate summer grafts, on the other hand, had contained only a partial supply of pabulum, enough to allow them to make six leaves and a top bud. After a few days of resting these shoots with meager larder could then go forward with new food furnished by the whole tree.

Mediate and immediate winter grafts were alike in their method of growth in the spring. This would seem to confirm the idea that character of new growth is dependent upon the relative quality of stored pabulum in the cambium layer.

In experimental work it was noted that both mediate and immediate winter grafts make a slower start in the spring than do the grafts inserted in springtime. This is perhaps due to the formation of a protective corky cell layer over wound surfaces. New granulation tissue would then find some degree of mechanical obstacle in the presence of a corky cell layer at first.

Herbaceous plants allow of grafting. We are familiar with the example of the tomato plant grafted upon the potato plant, furnishing a crop of tomatoes above and potatoes below.

It seemed to the author that the herbaceous growth of trees should be grafted quite as readily. This seems to be not the case. A number of experiments conducted with grafting of the herbaceous growth of trees in advance of lignification has resulted wholly in failure with both soft wood and hard wood trees.

The walnuts carried herbaceous bud grafts and scion grafts for a long time however. These grafts sometimes remained quite green and promising for a period of a month but lignification progressed in the stock without extending to the scion. Speculation would introduce the idea that lignification relates to a hormone influence proceeding from the leaves of a tree and that the leafless scion does not send forth hormones for stimulating the cells of the scion to the point of furnishing enzymes for wood building.

Perhaps the most interesting part of new tree work relates to experiments which are failures. Negative testimony is like the minor key in music. There are many men who care to do only things that "cannot be done." These are the ones who have made our progress in almost every field of human activity.