Part 6

Nearly all of the Chinese chestnut trees being grown at the present time are seedlings and exhibit a wide range of tree and nut characteristics. A few trees develop a somewhat more upright type of growth than that commonly seen, but this type is generally less productive than trees of more spreading habit, and the nuts are smaller and less desirable. Some trees showing the most upright type of growth originated from nuts imported from the more northern provinces of China and may represent a distinct strain or form of _Castanea mollissima_. The degree of incompatibility exhibited when southern China strains are grafted on northern China strains would indicate the same conclusion. Unfortunately, several different species or strains have been included in the plantings of most cooperators with the U. S. Department of Agriculture so that seedlings resulting from cross-pollination of these types may exhibit an even wider range of characteristics and performance from the standpoint of commercial production than is commonly seen at present. A few of these hybrids may be superior to pure _C. mollissima seedlings_ in certain important respects because of hybrid vigor, but taken as a whole the best types of _C. mollissima_ seedlings are superior to the other blight resistant species for purposes of nut production.

The earliest introductions of blight resistant chestnuts from the Orient are represented by very few trees in the Southeast, but a small number of plantings of trees distributed in 1926 have been observed. These are producing good nuts and the trees are quite healthy, regardless of conditions of planting except when they have been given no attention of any kind. In one planting the trees were planted about 10 feet apart on the square with the result that they are tall and spindly with nut production only in the tops and very light on a per tree basis, which indicates the need of adequate spacing if the trees are to be vigorous and productive. Incidentally, this close spacing has not resulted in a desirable timber type of growth.

In two other plantings the trees are planted in cleared areas in cut-over timber and then given no further attention. In both locations a few trees are still living but are of no value either for timber or nut production. In still another planting on a bench about halfway up a mountain, where infrequent cultivation or mowing is practiced, the trees are growing and producing moderately well but the nuts are small. A few other scattered plantings of a few trees each are doing well around homes though receiving only moderately good care.

The distribution of trees by the U. S. Department of Agriculture in 1935 and 1937 has resulted in a few plantings that have done moderately well. In one planting the trees are growing fairly well without care but are producing few nuts. In another planting the trees are planted on rather heavy soil that is terraced; they are given applications of commercial fertilizers and infrequent cultivations and have been producing fairly good crops of nuts in recent years. Still another planting of a considerable number of trees has been entirely removed through lack of interest of the new owner. The plantings described have all been on private property.

Plantings at various experiment stations have received somewhat more attention in general than those on private property; but because of lack of keeping quality of the nuts have not for the most part been accepted as a promising crop and have been the subject of very little study.

From the foregoing observations it is evident that the Chinese chestnut cannot withstand the effects of crowding either in a solid planting or in competition with native growth. The trees have performed moderately well with a minimum of care, but respond to good care by increased production and nut size. The rotting of the nuts soon after harvest as a result of improper methods of handling and storage has prevented an earlier acceptance of the crop as of potential economic importance in the Southeast.

+Experimental Studies at the U. S. Pecan Field Station, Albany, Georgia+

In 1926, twenty-eight seedling trees of _Castanea mollissima_ were planted in the Champion experimental block at Philema, near Albany, Georgia. These trees grew well and began producing nuts in 1932. In 1935, an additional 16 trees were planted in the same block. The trees in both plantings have shown good vegetative vigor and have been fairly productive. All the variations common to any group of Chinese chestnut seedling trees have been in evidence. One or two trees have lacked vegetative vigor but have produced heavy crops of nuts for their size. Type of bur opening has varied from free dropping of nuts to those burs from which the nuts are removed with difficulty; nut size has varied from about 35 to about 90 nuts per pound; the date of earliest and latest ripening of the nuts varies by about three weeks; nut color has ranged from light browns to dark mahogany and dark chocolate brown; and keeping quality and eating quality have ranged from good to poor. However, nut production, as shown by the data presented in Table I has been good and nut quality has been acceptable, so that with increasing knowledge of the storage requirements of the nuts the trees have paid a good profit in recent years. One of the older trees has consistently produced close to 150 pounds of nuts each year for the past few years.

Some of the trees in this planting have been topworked to selections from other plantings, including the variety Carr which showed up very poorly in comparison with most of the seedlings. Some of the trees have been culled out because of poor yield or nut size; and some have died as a result of poor drainage.

An additional planting at Philema in the Brown tract was made in 1938. The trees were planted in a portion of a five-acre block at some distance from the original plantings, with a spacing of 25 feet apart on the square in soil of rather light and sandy texture with fair subsoil drainage. The fertility was low but has been improved through the use of winter leguminous green manure crops and commercial fertilizers. Some of the trees planted consisted of trees grown from carefully selected _Castanea mollissima_ nuts imported from south China and designated by the initials MBA, MAY, MAZ, and MAX. Others carried the designating letters of "FP." The nuts from which these trees were grown were imported by the Division of Forest Pathology of the U. S. Department of Agriculture which also grew and distributed the trees. Still others were selections of _C. crenata_, the Japanese chestnut; and _C. mollissima_ selections from an experimental planting in California were also included. In 1940 the remainder of the five-acre block was planted with trees grown from seed produced by the original Philema planting.

Table I. Summary of chestnut yields at Philema, Georgia.

______________________________________________________ | | | HARVEST DATA | |______________________________| | | | 1926 and 1935 Planting[3] | Length |______________________________| Date Harvest | | Year Harvest Period | Yield No. Trees Av. Yield | Began in Days | in Lbs. Bearing per Tree | _______________________|______________________________| | | 1932 | 14 3 4.7 | 1933 | 7 7 1.0 | 1934 | 80 16 5.0 | 1935 8-29 22 | 222 22 10.1 | 1936 8-26 33 | 379 25 15.1 | 1937 8-26 37 | 278 18 15.4 | 1938 8- 6 42 | 480 21 22.9 | 1939 8-15 42 | 995 26 38.3 | 1940 8-27 38 | 740 34 21.8 | 1941 8-14 51 | 1,467 38 38.6 | 1942 9- 3 41 | 876 32 27.4 | 1943 9- 9 26 | 1,335 38 25.1 | 1944 8-15 44 | 560 29 19.3 | 1945 8-18 34 | 1,450 27 53.7 | 1946 8-20 41 | 1,455 28 52.0 | 1947 8-26 43 | 1,975 27 73.1 | _______________________|______________________________|

_______________________________________________________________ | | HARVEST DATA |_______________________________________ | | 1938 and 1940 Planting[4] Length |_______________________________________ Date Harvest | Year Harvest Period | Yield No. Trees Av. Yield Range in Began in Days | in Lbs. Bearing per Tree Yields _______________________|_______________________________________ | 1941 8-14 51 | 44 63 .7 .1-6.9 1942 9- 3 41 | 30 46 .7 .1-5.2 1943 9- 9 26 | 357 108 3.3 .1-29.7 1944 8-15 44 | 716 136 5.3 .1-37.0 1945 8-18 34 | 3,025 208 14.6 .1-50.7 1946 8-20 41 | 1,447 173 8.4 .1-48.3 1947 8-26 43 | 6,615 188 35.2 .1-108.5 _______________________|_______________________________________

[Footnote 3: 28 trees planted in 1926 and 16 planted in 1935, at spacing of 25 to 40 feet.]

[Footnote 4: 274 trees planted in 1938 and 60 in 1940, at spacing of 25 feet on square.]

The yield's produced in the 1938 planting have been outstanding, as indicated by the data in Table I, The trees began bearing when younger and developed heavier production than those of the 1926 planting, whether judged by age of tree or years of bearing. Many of the trees have produced nuts of outstanding size, attractiveness, eating quality, and keeping quality. There has been the usual degree of variation common to any collection of seedlings, but the best trees in this planting have been superior to any previously seen. Nut size has varied from 23 to more than 100 to the pound; the color of the nuts has varied from light tan to deep mahogany, and a few are nearly black. All have been of good eating quality. The keeping quality has varied materially, some keeping very well and others quite poorly.

Bur opening, has likewise varied so that at one extreme the nuts drop entirely free from the burs on some trees and at the other extreme the burs drop with the nuts in them and considerable work is required to remove the nuts. It is out of this group of trees that the three seedlings have been selected that the U. S. Department of Agriculture is considering worthy of variety status. These have not yet been officially released and no official description is yet available. The yield data for these three selected Seedlings are given in Table II.

Table II. Yield data by years, of three seedlings tentatively proposed for variety status, Philema, Georgia.

------------------------------------------------------------------------- Tree Proposed Yield in Pounds by Years Total yield No. Nuts (in Lbs.) per Lb. --------------------------------------- No. Name 1941 1942 1943 1944 1945 1946 1947 1948 from Planting ------------------------------------------------------------------------- 7880[5]Meiling .2 3.6 20.9 36.9 23.9 73.1 36.9 195.5 38-43 7919 Kuling 4.0 3.8 5.8 6.5 13.8 34.2 50.2 38.2 168.5 35-43 7930 Nanking .1 3.8 28.0 37.8 1.0 87.7 54.6 213.0 30-43 -------------------------------------------------------------------------

[Footnote 5: Meiling ("Beauty") is the first name of Mme. Chiang Kai-shek.]

The trees of the "FP" designation and, of other species were grown to fruiting, but have since been removed or topworked in entirety because of their lack of desirable characteristics and because they produced pollen for cross-pollination which would result in undesirable progeny when the _Castanea mollissima_ nuts were used for seed. Furthermore, a number of trees of the three-letter designations have been removed or topworked because they produced very small nuts, or showed poor keeping quality, or because of some other undesirable characteristic. Therefore, the nuts now being produced in this experimental orchard are of pure _C. mollissima_ inheritance of the best type, and, as such, represent some of the best and purest seed nuts available in this country today. This procedure is being continued so as to maintain the quality of the nuts for seed purposes at its present standard.

Unfortunately, many of the nuts offered in the general trade for seed purposes at the present time are coming from orchards composed of a mixture of species or types comparable to the 1938 Philema planting before culling. This is very undesirable because of the great variability in the nuts produced by trees with such an origin. When grafted or budded trees of the newer and improved varieties are available to orchardists chestnut growing for nut production may be based on the same sound practices as the other fruit industries.

In the topworking of "FP" trees at Philema with scions from other strains of _Castanea mollissima_ the degree of incompatibility has been so great, that the scion tops will have either blown out or died at the end of four or five years from grafting. At the present time this failure can only be attributed to the fact that the stocks were of mixed ancestry. On the other hand, scions of pure _C. mollissima_ placed on the same stock strains have made good unions and are entirely normal after as long as 13 years from grafting. This problem of incompatibility between stock and scion is one that yet remains to be completely solved.

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.]

+Harvesting and Nut Storage+

Harvesting of Chinese chestnuts has proved to have definite requirements if the nuts are to be obtained in the best possible condition. The nuts are quite susceptible to rots of several kinds and must be properly handled to keep losses at a minimum. They are also very easily and quickly injured by exposure to the sun, with the consequent, high temperatures and drying. If the nuts are to be stored for any length of time, as is necessary when they are to be used for seed purposes and as will be necessary when they are to be marketed for eating purposes during the Thanksgiving and Christmas holiday seasons, it is paramount that they be picked up from the orchard at not more than two-day intervals. Cleaning up all dropped nuts at daily intervals is most desirable.

At the end of each day the harvested nuts must be placed in cold storage at temperatures between 32°F. and 45°F. It has been found that a nearly air-tight container is required in order to maintain a relative humidity of 100% and prevent too much drying of the nuts. A 50-pound tin lard can with one 20d nail hole in the side near the lid has proven to be a good container for large quantities and these same cans also make good shipping containers merely by wiring on the lids. One-gallon friction top syrup cans with a single nail hole in the side make a good container for smaller quantities. In air-tight containers the nuts do not decay but germination capacity is quickly destroyed and bitter flavors develop quite rapidly. Nuts to be used for eating purposes shortly after harvest may be stored at lower relative humidities but should be placed in cold storage. A loss of about 15% in weight from the fresh weight of nuts is necessary to reach proper eating quality. Nuts dried to this extent are sweet and palatable but cannot be stored for any length of time and fail to germinate well when planted.

The experimental study of chestnut storage problems is being continued with the hope of working out still better methods. The manner of marketing chestnuts so that they will reach the consumer in a desirable condition also is still to be worked out, but it appears possible that retail cold storage and packaging in moisture-proof bags which are pervious to CO_{2} and O_{2} give promise at present. Probably the most promising aid to an increased storage life of chestnuts will come through the selection of trees for propagation and planting that produce nuts of superior resistance to storage rots. There is rather great variation among seedlings in this respect, some being-quite superior, although no completely resistant seedlings have yet been found.

+Discussion and Conclusions+