The topworking of trees in the five-acre block at Philema has been generally successful where incompatibility is not a problem. Bearing-size trees topworked one spring will generally produce a few nuts in the second subsequent growing-season. Growth the first year after grafting will frequently be as much as 12 feet long and very stocky. Both cleft grafting and inlay bark grafting have been practiced, the latter method proving to be the more satisfactory from all standpoints. In this method of grafting scaffold limbs from 1 to 6 inches in diameter are cut off square across. Scions 6 to 8 inches long are prepared by making a slanting cut 2 to 3 inches long and ending about three-fourths through the scion at its basal end. A strip of bark just wide and long enough to receive the scion, with about one-half of the upper end of the bevel showing above the cut surface of the stub, is then removed from the stub. The scion is then nailed into place with 5/8-inch nails and painted over with melted grafting wax. Two or three scions are required for most stubs. This work is done just as growth is starting in the spring and the bark is slipping well. The scions may generally be cut directly from the trees, but sometimes they may need to be cut several days earlier and stored in damp material in a refrigerator to keep them dormant.
In south Georgia the Chinese chestnut normally begins growth soon after March 1, but in some years it has started as much as a month after this date. Between south and north Georgia there is a differential in the time growth starts in the spring of one to two weeks. This differential also carries over into the date of blossoming and the date the harvest period begins. In south Georgia pollination generally occurs during the latter part of April and early part of May, and the harvest period begins about 100 days later. The peak of harvest averages 185 days after the initiation of growth in the spring. Dormancy comes only after the first frost sufficiently heavy to kill the leaves, usually about two months after nut harvest is completed. This period between harvest and leaf fall is undoubtedly an important factor in the annual bearing habit of the chestnut in the Southeast since it permits the food reserves in the tree to be replenished after the crop is mature. This is true under favorable conditions but does not hold under conditions of crowding, low soil fertility, or premature defoliation. For best growth and production the tree should be in foliage approximately nine months out of the year.
+ORCHARD MANAGEMENT+
The planting of chestnut trees in the Southeast should be done as soon as possible after the trees become dormant in the nursery. They should be planted on fertile soil which is well drained but not subject to serious drought injury. The Chinese chestnut cannot withstand a high water table, or free standing water, but appears to be somewhat resistant to drought injury when once well established. The chestnut trees have not yet reached an age at which their largest potential size has been attained, but trees of 50-foot spread have been observed. It appears likely, then, that orchards should be planted at 50 to 60-foot distances on the square, unless closer planting and subsequent thinning is resorted to in order to build up high nut production per acre at an earlier age of the orchard. Planting distances of 25 x 25 feet, 30 x 30 feet, 25 x 50 feet, and 30 x 60 feet are recommended for this reason, but only if the orchardist will plan to thin the stand at 10 to 15 years of orchard age and at later intervals as required. In no case should the branches of adjacent trees be allowed to touch as under such conditions competition between trees will reduce the yield per tree and nut size, and induce alternate-year bearing.
In planting the young tree it is usually advisable to fill the hole in which the tree is to be set with top soil, packing it firmly around the roots as the hole is being filled. Usually no fertilizer is used at the time of planting, although mixing about a handful of bone meal with the soil around the roots has given a higher percentage of living trees and has increased growth the first year. A shallow basin around the tree to facilitate watering when necessary during the first growing season, or the application of a mulch around the tree, or both, will be helpful in obtaining a high percentage of living trees and good growth. Adding water at the time of planting is good insurance that the soil will be well settled around the roots. A wrap of newspaper tied loosely around the trunk of the young tree will aid in preventing winter injury and sun-scald.
Under conditions of little or no care the seedling chestnut tree will generally develop several trunks as a result of the forcing of multiple sprouts from near the ground line. The tree should be trained to one trunk, as such a form seems to be less susceptible to winter injury while young and makes a much more desirable orchard tree when older. Pruning of the young trees subsequent to the development of the head at a 4 to 5-foot height should be confined to the removal of crossing branches and those so near to the ground as to interfere with the necessary cultivation and harvesting work under the tree.
Most soils in the Southeast are somewhat low in fertility and must receive good care if chestnuts are to grow well. The annual application of commercial fertilizers is generally required as is the growing of a winter green manure crop, preferably a legume. One of the most satisfactory systems is to plant hairy vetch, Austrian winter peas, or blue lupine[6] in late October or early November, applying broadcast at the time of planting from 400 to 600 pounds per acre of a 0-14-10 or 0-14-7 fertilizer mixture. This green manure crop should then be disced in by April 15 of the following spring, with subsequent shallow cultivations at about six-week intervals through the growing season. The ground should be clean by the middle of August to facilitate harvesting the nuts. If such a system of culture is not feasible, as on too steep slopes or around buildings, mowing or mulching can be used to advantage, but the trees must be given annual applications of a complete fertilizer mixture, such as 4-8-6, 6-8-8, or 5-7-5. These should be made each year about a month before growth starts at a rate of 2 to 3 pounds for each year of tree age. This should be broadcast under and slightly beyond the spread of the branches.
It has not yet been found necessary to spray the trees for the control of any disease or insect. This does not indicate that control measures may not be required at some time in the future, for it is the history of horticultural crops when planted in any concentration that diseases and insects increase in number and degree of injury. As yet, the chestnut weevil has not been found at the lower elevations in the Southeast.
In a few plantings a condition causing some premature defoliation has been observed at infrequent intervals. The condition begins as a leaf scorch which may or may not develop to the point where the leaf drops. It is thought to be caused by some mineral deficiency or unbalance associated with erratic weather conditions, but the exact cause is yet unknown. A leaf spot disease has been observed but has caused no appreciable defoliation and no control measures have been thought necessary.
[Footnote 6: Blue lupine is winter-hardy only in the warmer coastal areas, not adapted north of Columbus, Georgia, Meridian, Mississippi, or Shreveport, Louisiana. Ed.]