3. They require more care.—This objection stands particularly against the dwarf trees trained in special and intricate forms. Such trees undoubtedly do require more careful attention, more frequent going-over, and more hand work in the course of the year. It is probably not true that apples, pears, plums or peaches in bush or pyramid forms require any more labor or attention than standard trees to secure equally good results. On the other hand it must not be forgotten, as has already been pointed out, that whatever care may be required is much more easily given the dwarf trees than the standards.
4. They are not a commercial success.—This statement, too, though undoubtedly having some truth in it, can not stand without qualification. It is certainly true that no one could grow ordinary varieties of apples, like Baldwin or Ben Davis for instance, on dwarf trees in competition with men who are growing the same varieties on standards. It is probably true that fancy varieties of apples can be grown with profit on dwarf trees, but even this can not be strongly urged. So far as apples are concerned the chief value of dwarf trees for modern commercial enterprises in America will come through their use as fillers between rows of standard trees. In the case of pears the situation is somewhat more favorable to dwarf trees. There are a number of orchards in this country where pears have been successfully grown for market, these many years, on dwarf trees. The famous and everywhere planted Bartlett succeeds admirably on the quince stock wherever the soil is suited to it. No successful commercial orchards of dwarf peaches or plums can be cited in this country, individual trees of these kinds even being extremely rare; yet there is good reason to suppose that under favorable conditions dwarf peaches and plums may have some commercial value. Such value may be more in the way of supplementing standard trees than in superseding them, but it is still worth consideration. So that, after all, when we say that dwarf fruit trees are not a commercial success we mean merely that they will not take the place of standard trees. The large market orchards must always continue to be made up of standard trees; but in their own way the dwarf trees will find a limited place even in commercial operations, and this use of them seems destined to be more general in the future than it has been in the past.
III
PROPAGATION
The propagation of dwarf fruit trees is in some senses a more critical and interesting problem than the propagation of ordinary nursery stock. The successful production of a dwarf fruit tree depends primarily on its propagation. The selection of stocks for dwarfing purposes is necessarily a complicated matter. Under the terms of the problem it is impossible that the stock and the cion which are wedded together should be very closely related. The stock must be distinctly different and pronouncedly dwarfer in his habit of growth.
It is not always an easy matter to find a stock which is thus distinctly different from the tree which it is desired to grow and which will at the same time form with it a vigorous and long lived union. It is necessary further that the propagation can be carried on with ease and with a fair degree of success in commercial nurseries. If difficult methods of grafting are required, or if only a small stand of nursery trees can be secured, the undertaking becomes too expensive from the nurseryman's point of view.
The methods of propagating dwarf trees are for the most part the same as those used in reproducing the same kinds of fruit on standard stocks. As a matter of fact nearly all dwarf trees are propagated by budding. Apples, pears, and plums can be readily grafted, but budding is simpler, speedier, and usually the cheaper process in the nursery. In the upper Mississippi Valley, where plums are somewhat extensively worked on Americana plum roots, grafting is rather common. The side graft and the whip graft are the forms most used.
The theory of the production of a dwarf fruit tree by the restraining of its growth has already been mentioned in another chapter. The dwarf stock simply supplies less food than is required for the normal growth of the variety under propagation, and the tree is, in a sense, starved or stunted into its dwarf stature.