for seedling trees to come into bearing, propagation from roots probably requiring the same length of time as propagation from seed, whereas by budding or grafting the bearing period begins very much earlier. Forty-six years ago Mr. J. W. Kerr of Denton, Maryland, planted three pecks of large shagbark hickory nuts, but of the progeny only about twenty were satisfactory, most of the trees bearing inferior nuts. These trees required from thirteen to eighteen years to come into bearing, and young trees that Mr. Kerr purchased from nurseries and planted were twenty-five years old before they began to bear. Others who have planted shagbark hickories and pecans state that nearly twenty years are required for the trees to come into bearing on an average. When budded or grafted the pecan sometimes comes into bearing in two years, and frequently in four years. We may anticipate that other hickories will act analogously.
The hickories prefer rich, well drained soil for best development of nuts, and an abundance of moisture, provided the land is well drained. Many of the hickories, however, are so adaptable to various soils that they often thrive in lands that are sandy, and dry, and almost barren. In the latter case, they have to maintain an enormous root system for feeding purposes, and this is detrimental to good bearing qualities. The mocker-nut, pignut, and hairy hickory, perhaps adapt themselves best to sandy soils. This feature may make them valuable species for planting when one has no other soil, because the stocks can be used for grafting better kinds.
While the hickories prefer neutral or alkaline soil, most of them will grow fairly well even in acid glacial tills. Their preference, however, for neutral or alkaline soils would suggest the use of a good deal of lime in acid soils, when hickories are to be grown in orchard form.
All of the trees in the hickory group are intolerant of shade and of competition with other trees. The more sunlight they can have the better. Most of us are familiar with the hickory tree standing alone in the cultivated field, which bears a heavy annual crop, when the neighbors at the edge of the forest bear sparingly. Hickories in forest growth put their energies into the formation of wood chiefly, and in the struggle for food and light devote very little energy to fruiting.
The best method for cultivation of hickories has been worked out only with the pecan up to the present time. With this species, it has been determined that clean cultivation with plenty of fertilization gives best results, as with apples. It is probable that Stringfellow's sod culture method will come next in order, and will perhaps be most generally used by nut orchardists, because it is less expensive and requires less labor. The sod culture method includes the idea of cutting all grass and weeds beneath the trees, in order to take away competition, allowing these vegetable substances to decompose beneath the trees and furnish food. There is no objection to adding artificial fertilizer, or a still greater amount of vegetable matter.
The enemies of the hickories are not many in the forest, where the balance of nature is maintained, but when man disturbs the balance of nature by planting hickories in large numbers in orchard form certain enemies increase, and must be met by our resources. Fungous and bacterial enemies are beginning to menace some varieties of the pecan in the South, and both in the North and in the South certain insect enemies are becoming important in relation to all valuable hickories.
The bark boring beetle (Scolytus) has been reported as destructive to hickories in some sections, the trees dying as a result of depredations of the larvae of this beetle.
I find a large borer at work on some of my hickories, but have not as yet determined its species. It may be the painted hickory borer (Cylene), or the locust borer. It makes a hole as large as a small lead pencil, directly into the trunk or limbs, and excavates long tunnels into the heart wood. The painted hickory borer is supposed to occur chiefly on dead and dying hickories, but the borer of which I speak is found in the vigorous young hickories in the vicinity of my locusts, which are riddled with locust borers.
In some localities involucre borers make tunnels between the nut and the involucre, interfering with the development of the kernel.
The hickory twig girdler (Oncideres) is abundant in some localities, but not as yet very destructive.
Hickory nut weevils destroy many nuts in some localities, and their colonies increase about individual trees markedly. In such cases, it is important to collect the entire crop each year from a given tree, taking pains to destroy all nuts which contain weevil larvae. These may be selected in a general way by dumping the freshly gathered nuts into a tub of water. Nuts containing weevil larvae will float for the most part, and in order to make sure of the destruction of larvae in the remaining nuts they may be placed in a closed receptacle, and carbon bisulphide poured over them.
One of the bud worms is sometimes very destructive to individual hickory trees which have developed colonies, the larvae destroying the axillary buds, and burrowing into the base of the petioles of leaves.
A new enemy which I found this year for the first time is the Conotrachelus juglandis. This beetle ordinarily lays its eggs in the involucre of the butternut. With the introduction of exotic walnuts, the beetle has changed its habits, and lays its eggs in the herbaceous shoots of walnuts and hickories. The larvae tunnel into the center of a shoot, and destroy it, or seriously interfere with its nutrition.
Among the enemies of the hickory we must not forget the common field mouse, and the pine mouse, which burrow beneath the surface of the ground, and in winter feed freely upon the bark of the roots of the hickories. They have destroyed many thousands of young hickories of various kinds in my nursery, and in digging up roots of old hickories for experimental root grafting I find that mice have been living freely for years upon the bark of some roots.
Aside from the facts which have been grouped together in this paper, certain notes may be of interest, as introducing questions for speculation.
Are we likely to find more species among the hickories than the ones already described? If so well described a species as the H. Buckleyi has almost escaped observation, and if H. Mexicana is confined, as it seems to be, to a very limited area, and if most of the hickories grow in regions where few botanists are at work, it seems to me probable that several species remain as yet undiscovered. These are likely to be species which lack means of defence, and which are restricted to certain small areas. If we make a parallel with other observations of recent discoveries, one thinks, for instance, in Ichthyology of the Marston's trout, the Sunapee sabling, Ausable greyling, and the Kern River trout, confined almost to a certain stream or lake, and remaining undiscovered for years by naturalists, although familiar to thousands of local fishermen.
Sometimes there is a very apparent reason for the check to distribution of a species. The men whom I employed to go into the mountains of Alvarez for the Mexican hickory tell me that the trees are so loaded down with mistletoe that they rarely bear a crop, and there are few nuts with well developed kernels to be found.
Distribution of a powerful species of hickory, like the pecan, seems to be limited in the North by incomplete development of the pistillate flowers. These are borne on the ends of the herbaceous shoots of the year, and the pecan has such a long growing season that in the North the pistillate buds, which are last developed, are exposed to winter killing. Southern limitation