Soil, Location and Climate.—European varieties of the filbert thrive best in what may be termed a rich loam, with a dry subsoil. If the soil is too moist, the trees are inclined to run too much to wood, producing less fruit. In the famous nut orchards of Kent, England, the soil is loam upon a dry, sandy rock. The trees in these orchards are manured at least once in two years, especially after they reach the full bearing age. Almost any good soil that is rich enough to produce a good crop of corn, and is not submerged in winter, will answer for the filbert in this country.
In selecting a location for a filbert orchard, an open, airy one would probably be preferable to a spot so sheltered as to cause the flowers to appear so early as to be injured by frosts. Furthermore, I would warn cultivators to keep as far away as possible from any hedgerows or plantation of the wild native hazel bushes, for these are always loaded with disease germs that are fatal to the foreign species. We might reasonably suppose that filberts would succeed better in the Southern than in the Northern States, but if the experience of those who have tried them there count for anything, then these nuts are not adapted to the South, owing to the fact that the flowers almost invariably push out during warm days in winter, and these are destroyed later by frosts. In the more elevated regions of the northern border of the Southern, and in similar locations in the Middle States, these nuts will doubtless thrive, or at least the climate will prove congenial. The more equable the climate and free from extremes in temperature, the better; but the most important element in this country is moisture, especially in summer, when the nuts are filling out; and the best way to supply this, where irrigation cannot be practiced, is to keep the ground around the trees continually covered with a mulch of leaves or other coarse vegetable matter.
Planting and Pruning.—The space to be allowed between the plants, when set out for bearing, will, of course, depend very much upon the size they are expected to attain. Those varieties which assume and remain in the bush form may be planted very close together, or not more than six to eight feet between the plants; but those which become small trees must be given more room. The larger European sorts, which are at present the only ones worth cultivating for their nuts, should be set ten or twelve feet apart, and the rows fifteen to sixteen feet, then if properly pruned they will shade the ground and be in a convenient form for gathering the crop. The trees may be planted in the orchard when quite small, and some kind of vegetable crop grown among them for the first two or three years, but I would prefer keeping the plants in nursery rows until they were four or five feet high, and then transplant to the orchard, and set a short, stout stake by the side of each, to keep the main stem in an upright position until the tree is well established.
The first pruning,—except removing suckers from those in the nursery rows,—will be the heading back of the main or central stem to a hight of two or three feet, for the purpose of laying the foundation, as it were, of the head of the future tree. Three or four of the larger branches, which will push out from near the top of the severed main stem, are to be selected to form the top, and all others removed. Small lateral branches or twigs will spring out from the larger or main ones, and in this way the head of a bearing tree is formed. But before attempting to prune a mature or fruitful tree, we must consider the mode of fructification, for the filbert does not bear nuts on the young growth of the season, as in the chestnut, but on the small branchlets or spur-like twigs of the preceding season, or, as we may say, on the one-year-old twigs. The small fruiting twigs are seldom more than four to six inches long, and sometimes almost every well-developed bud on these contain pistillate flowers and embryo nuts, either singly or in clusters. In pruning the bearing trees, the main point to be observed is to head back the strong leading shoots, to prevent the trees growing too tall, as well as to force out the side or lateral twigs as fruiting wood for the ensuing year. If the heads of the trees become too much crowded to admit light and air to the center, some of the larger branches must be removed entire. The best time to prune is in early spring, when the trees are in bloom, for at this season we can readily determine the injured from the sound male catkins, and preserve enough of these to insure perfect fertilization. It is not necessary, however, that there should be healthy pollen-bearing catkins on every tree in an orchard, for if one in a dozen is well supplied, there will be sufficient to fertilize the flowers of all growing near by. It often happens, in our rather severe climate, that the catkins of some trees or varieties are winterkilled, while the pistillate flowers enclosed in the buds escape injury, and when this occurs it is well to have some hardy variety at hand, from which pollen can be obtained when needed. The inferior varieties are usually the most hardy, and the wild European hazel or our northern beaked hazel, will usually escape injury where all the large improved sorts fail, and it requires but a few minutes' labor to cut branches bearing sound catkins, and scatter these about through the heads of trees requiring such assistance to make them fruitful.
SPECIES OF AMERICAN HAZELS.
Corylus Americana (Walters). Common hazel bush.—Leaves roundish, heart-shaped, pointed, coarsely serrate; husk somewhat downy, with a wide, flattened, fringed border extending beyond the roundish nut. Shell rather thick and brittle; kernel sweet and good, but the nut is too small to be considered of much value. A low shrub, with many stems springing from the roots. Young shoots and twigs downy and glandular-hairy. Common in woods and old fields from Canada to Florida.
Corylus Rostrata (Aiton). Beaked hazel.—Leaves ovate or oblong, somewhat heart-shaped, pointed, doubly serrate; husk extending an inch or more beyond the round or ovoid nut, forming before it opens a long tubular beak, hence the name. The husk is densely covered with nettle-like bristles, which are quite irritating to tender hands. The nuts are small, usually growing in clusters at the ends of the twigs, only a few coming to maturity. A low shrub or small tree, usually growing in a dense clump, not spreading from subterranean stems, as in the last species. Common on rather firm and rich soil along the borders of streams, in the northern border States, and southward on the Alleghanies, but most abundant in the north through Canada, and westward to the Pacific in Washington and Oregon, where, in the mountains, it often assumes the tree form, growing to a hight of twenty-five to thirty feet, with a stem from four to six inches in diameter. The wood is light, soft, and very white to the center. It also extends southward to central California, but here it is only a small bush, this form having been described under the name of Corylus rostrata, var. Californica, A. de C. This species probably reaches its highest development in the Cascade range, in northern Oregon. The same or a closely allied species of the hazel extends far into northern Asia. There are no improved varieties of either of our native species of the hazel in cultivation.
EUROPEAN SPECIES OF CORYLUS.
[FIG. 39]. CONSTANTINOPLE HAZEL.