In general, Asiatic chestnuts, when grown for timber purposes, are best adapted to northern slopes, above frost pockets on cool protected sites, on deep, fertile soils having a covering of leaf litter and humus in the top soil, a soil that is permeable to both roots and water, and that has a good water-holding capacity. The plant association, above mentioned as indicating ideal sites for Asiatic chestnuts for best timber development, occur in rich soils of slight hollows in moist hilly woods and on the mountains in cove sites.
Improved Methods of Storing Chestnuts
By H. L. Crane and J. W. McKay Plant Industry Station, Beltsville,
Maryland
Trees of the Chinese chestnut, Castanea mollissima, are quite resistant to the chestnut bark or blight disease. The heavy bearing of the trees together with the good quality of the nuts produced has stimulated planting of trees to replace those of the American species largely killed by that disease. Although a few horticultural varieties of Chinese chestnuts have been introduced and propagated, the great majority of the bearing trees are seedlings. In seedling plantings seldom do two trees produce nuts of the same size, color, and shape. All of these nuts when properly harvested, treated, and stored are sweet and edible and nourishing as food either raw, boiled, roasted, or combined with other foods in poultry dressing, salads, or pancakes. Then too, there is a big demand for Chinese chestnuts as seed for the purpose of growing seedling trees to be planted in orchards or to be used as rootstocks in propagating horticultural varieties. In either case, it is often desirable to store the nuts for several months before using them.
Chestnuts are not like the oily nuts, such as pecans, walnuts, almonds, filberts, or peanuts, that must be dried to a moisture content of 5 to 8 per cent to store well. Chestnuts are starchy nuts, containing about 50% moisture when first harvested, and on drying they become very hard. In experiments conducted at the U. S. Horticultural Field Station, Meridian, Miss., it was found that the loss in weight of chestnuts ranged from 16.2 to 30.5% when stored for 4 months in open containers at 32°F., and 80% relative humidity. In an experiment in which chestnuts were stored 4-1/2 months at 32°F., they lost 18.8% in weight when stored in burlap sacks, 3.7% when stored in waxed paper cartons with tight-fitting lids, and 2.0% when stored in friction-top cans. Furthermore, chestnuts on drying lose their viability and become worthless. Chestnuts lose moisture rapidly and become subject to spoilage due to molds and other fungi and therefore must be considered as highly perishable and handled accordingly.
There is a great difference in the keeping quality of the nuts produced by different trees in that some are very susceptible to infection by molds and bacteria and spoil quickly while others keep quite well. At Meridian, Miss., nuts from 5 different seedling trees ranged from 2 to 34% mold infection at harvest. Studies made by John R. Large at U. S. Pecan Field Station, Albany, Ga., showed that much of the infection of the nuts by molds occurred after they had fallen from the burs and while the nuts were in contact with the soil. It is, therefore, essential that the nuts be harvested promptly after they are mature.
As a general practice the nuts should be gathered every other day during the ripening season. Burs that have split open and exposed the brown nuts should be knocked from the trees, and all of the nuts on the ground should be gathered up cleanly. It would be difficult to emphasize too strongly the importance of harvesting the nuts promptly as soon as they are mature. Prompt and careful attention must then be given to the conditions under which they are stored if they are to remain for long in an edible and viable condition.
After the nuts have been gathered[10] they should be held in a layer not exceeding 1 or 2 inches deep for 3 or 4 days. It is important that they be kept in a well-ventilated building and that the sun does not strike the nuts during curing. After the preliminary curing, the nuts should be placed in friction-top metal cans (slip-top cans) and the lids should not be tight for the first month of storage. The nuts contain enough moisture after the short curing process that the lids will "sweat", or surplus moisture will accumulate on the under side. This will disappear slowly by evaporation during the first month or 6 weeks of storage and the lids may then be pushed firmly into place, making the can nearly airtight. The containers of nuts should be held in cold storage at temperatures of 32° to 36°F. While some nuts have kept quite well at temperatures as high as 45°F., the tests indicate that the nearer the storage temperature is to 32°F., the less is the mold development. Placing the cans in an ordinary home refrigerator should prove fairly satisfactory with nuts that have good keeping quality.
[Footnote 10: If the nuts are infected with weevils, they should immediately be treated after harvesting with the hot water or methyl bromide treatment as recommended by the United States Department of Agriculture, Bureau of Entomology and Plant Quarantine.]
It is essential that the nuts be placed in storage immediately after they have had the preliminary curing. Any delay may increase the possibility of mold development.