A matter of importance in the selection of varieties of apples, and even more markedly of pears, is the determination of the fertility of the blossoms. Sterility, indicated by annual dropping of the fruit, may result from one or a combination of the following causes: Im potence of the pollen or the pistils, or the pre mature ripening of one or the other; injuries to the blossoms by fungous attacks, rain, frost, or continued cool weather or other cause more or less beyond the grower's control. On the other hand, it often results from impotence of the pollen to fertilize the pistil of the same variety and is noticed when trees stand singly or in blocks of one variety remote from other varieties. This may be obviated by the grower, who should Plant varieties that blossom at the same time in proximity, usually in alternate rows through the orchard, or by grafting such in orchards already set. A practice resulting from this and the varying maturity of varieties with respect to fruit-bearing is the planting of fille r') trees in permanent orchards. The fillers are quick-maturing varieties of usually upright growth and small size, which are set alternately with the slower-growing, more-spreading per manent trees, and cut out when crowding seems to threaten. For such practice four varieties are usually selected, two fillers and two perma nents, each pair blossoming at the same time. Each pair is placed alternately with the other and each member of the pair alternately with its partner. Trees in such orchards are often planted 28 feet apart on the diagonal, so that when the fillers are removed the permanents will be left in rectangles of about 40 feet, the Usual distance recommended for large-growing varieties. Some growers plant as close as 30 feet, but this is too close except for trees of small growth. No other tree fruit than the apple should be planted in an apple orchard, because no two fruits demand the same treat ment, and where two are planted, one or the other, perhaps both, must suffer more or less. See ORCHARD CULTURE.
New varieties of apples are propagated from seeds, but since seeds rarely improve upon the parent, seedlings are chiefly used to produce stocks for grafting or budding. Standard (that is, natural-sized) trees are so propagated. Dwarf trees result from grafting or budding the same varieties upon the small growing, almost bush-like varieties, paradise and doucin, the stocks of which are produced by mound layering. Voluminous discussion has arisen concerning the relative advantages of grafting over budding, and also concerning cer tain methods of grafting. Opinions in the first case are very conflicting; in the latter they seem to favor the use of a small piece of apple root as stock and a rather long scion to be set deeply in nursery and orchard in order to ensure the rooting of the scion and thus obtain a tree drawing its nourishment from its own roots instead of from the nondescript roots of the seedling stock In northern rigorous climates very hardy varieties are selected upon which to top-work less robust sorts, thus to increase their hardiness. When the trees are set the
tops must be cut back severely to balance the loss of root due to digging from the nur sery and to start the head at the proper height from the ground. Formerly six feet was the usual length of trunk desired, but half that length is now preferred and in the central West ern States even less. Trees with short bodies and low heads are less likely to be injured by wind and sun-scald than those with high heads and long bodies. Established unprofitable trees and undesirable varieties are often top-worked to valuable ones; not more than a third of such trees being grafted each year because of the .danger of producing water-sprouts. See GRAFTAGE; PRUNING; TRANSPLANTING.
Soils, Fertilizers, etc.— Apples thrive upon nearly all kinds of soils, certain varieties being better adapted to light soils and others to heavy rather than the reverse in each case; but the great majority of the almost innumerable varieties succeed best upon medium to clayey loams, especially if they are somewhat elevated, inclined or rolling, and in a clear, dry climate.' Since air and water drainage are usually good in such places the fruit produced is generally of fine color, flavor and size. Upon low lands and in damp climates the fruits are usually of inferior quality and the trees more susceptible to fungous attacks (see ORCHARD). The fer tilizers demanded by apples are mainly potash and phosphoric •acid (see MANURES). Some growers use a mixture of 100 pounds of muriate of potash to 200 pounds of 16 per cent super phosphate at the rate of 100 pounds an acre while the trees are small, increasing to 500 pounds and even as much as 1,500 pounds an acre for trees in full bearing, the amount de pending upon the character and condition of the soil, and the grower's management. If cover Crops (see GREEN MANURING) such as clover, vetches or cow-peas are grown, they will supply all the needed; indeed, if long con tinued or if several very heavy crops be turned under, too much nitrogen may accumulate, and recourse to a cereal crop be to re move the excess. Too much nitrogen induces a sappy, easily winter-killed growth, generally at the expense of fruit-production. Lack of nitrogen is indicated by pale green or yellowish foliage. The preparation of the land does not differ materially from that for other crops such as corn or potatoes, each of which is often grown the season previous to planting in order to fit the land for the orchard. The trees may be set in spring or autumn and the cost of Cultivation may be met by cropping the land for the first few years with potatoes, melons or some other low-growing, inter-tilled crop. An nual cultivation consists in an early spring plowing followed by narrowings at intervals of two weeks and after rains that form a crust until mid-summer, when a cover crop is sown to be turned under in the following spring. Deep plowing during the first five years or so will induce deep rooting which in after years will assist in withstanding drought and obviate the necessity of annual deep plowing. See TILLAGE.