Nurserymen in the future will have to deal with this transplanting problem in a different way than the old time nurserymen who handles fruit trees. A suggested way to improve the root system and at the same time make it easy to lift the tree with a ball of dirt, similar to the way an evergreen is transplanted, is to prepare a pocket of special transplanting soil previous to the lining out (which is the term used by nurserymen in setting out seedlings preparatory to grafting them in nursery rows). A suggested balanced soil for making the method practical is to use 1/2 by volume of peat moss; the other half should be rich, black sandy loam with very little clay mixture in it. In other words, each nut tree should be allowed about a bushel of soil for its development, 1/2 bushel to be peat moss, the other half bushel to be represented by rich black loam. This mixture will encourage many fibrous roots to develop and when the tree is dug, approximately all of this bushel of soil will be retained around the roots. Having such a high proportion of peat moss makes it lighter than ordinary ground; such a ball and the tree will weigh approximately from 100 to 125 pounds which can be shipped by freight at a low rate and is well worth the extra price that nurserymen must ask for a specimen of this kind. Such trees have really never been unplanted and for this reason do not suffer the shock which is inevitable in the usual transplanting process. Although pre-planted trees are more expensive to buy and to transport, their improved chances of living make them worth the price. The above recommendation is especially applicable to young grafted hickory trees since they are among the most difficult trees to transplant satisfactorily. The English walnut (Persian), black walnut, butternut and especially the hickory are improved by the use of a handful of ground lime mixed with the soil in preparing these pockets which will later constitute the ball surrounding the roots of the tree to be transplanted.
There is a tendency in grafted trees to produce sprouts below the graft. Unless these are rubbed off, the grafted portion will become discouraged and the tree will revert to a seedling variety. Filberts should never be allowed more than two or three stems, or trunks, while one is more preferable. If they are allowed to have more, they will produce a rank growth of wood but only a few, if any, nuts. I stress, by repeating, that trees should not be planted too deeply and that great care must be taken to eliminate air pockets. Extra effort and nursing of transplanted trees during the first season will be repaid by their successful development and growth.
It is a wise precaution to place a protective screen around the trunk of each tree to prevent rodents from attacking it. Mice gnaw off the bark near the ground, sometimes girdling a tree and so killing it. Rabbits chew off branches and they, too, may girdle the upper part of a tree. Rabbits are very fond of pecan and hickory bark. In some places, it may be necessary to encircle each pecan and hickory tree with a three or four-foot rabbit fence until the tree is large enough to lose its appeal to these nuisances.
Compared with the number of insects which infest fruit trees, very few attack nut trees. One of those which does is the walnut-leaf caterpillar. These appear as a closely congregated group of small worms which feed on the leaves of black walnut and hickory trees during the latter half of the summer season. Very often they are all to be found on a single leaf, which should be picked from the tree and crushed underfoot. A simple spray of lead arsenate of the strength recommended by companies selling spray material, will effectively rid trees of these pests. Another insect often found in a nut orchard is the oak tree girdler, which also is active in the latter part of the summer. It often causes limbs as large as an inch in diameter to be cut through and to fall to the ground. By removing such freshly girdled branches and cutting into the hollow made by the larva, it is possible to find the live worm and destroy it. A good way to combat this pest is to keep each tree pruned of all dead branches and to burn all broken and dead wood each fall. While some nut trees are subject to other insects, the two described here are the most frequently found. Fortunately, they are easily controlled if a watch is kept for them.
Chapter 14
WINTER PROTECTION OF GRAFTS AND SEEDLINGS
It is not enough to make a successful graft and to watch it carefully during the growing season, picking all sprouts off the stock, spraying it so that insects will not chew the tender leaves and bark, bracing it against windstorms and perching birds. Each graft must also be protected from winter injury. For many years I have studied and experimented to find a successful way of achieving such protection. To enumerate my many experiments, from simple to far-fetched, would be to write another book quite as long as this one. My conclusion, now, is that there is little one can do to assist nature in the process of acclimatizing grafted plants and seedlings.
I have repeatedly noticed that the place where most damage is done by the cold is at the union between stock and graft. For example, I observed this on the European walnuts, imported from Poland, grafted to Minnesota black walnut stocks. Although both the buds and the wood of the top remained fresh and green, the unions suffered severe, and sometimes total winter injury. In grafts where the latter occurred, the dead cells soon caused the wood to ferment and sour. Occasionally, a small group of healthy cells succeeded in re-establishing circulation with the unharmed, grafted top and the graft, continuing its growth, would eventually overcome the injury it had suffered. I have seen this occur with grafts of English walnut, apricot and pecan.
A blackbird's nest in the crotch of a small tree suggested to me the most satisfactory guard I have yet found against this greatest of dangers to all exotic, grafted varieties of nut trees. The nest, which enclosed over half of the graft union, was partly composed of woolen fibers which its builder had gathered from barbed-wire fences that sheep had brushed against. On the exposed portion of the graft union, discoloration indicated injury and dead cells, but on that part covered by the nest, all the cells were alive and green. I have improved on the bird's nest by wrapping a large wad of wool loosely around each graft union. The value of wool is that it will not collect moisture and so start fermentation. It allows the cells to breathe, yet protects the union from the shock of temperature extremes. Birds will inevitably steal some of the strands of wool but this activity in and about the trees means a decrease in injuries from insects—a worthwhile exchange.