They do not come with instructions for their maintenance. Deciduous fruit trees, particularly the stone fruit trees (such as cherry, plum, prune, apricot nectarine and peach) and pomme fruit trees (such as apple and pear), can be procured as easily as nasturtium seed or petunias. Whether bare-root in winter or canned (potted), they very often get planted into gardens where they are expected to produce their fruit as easily as daisies bloom.
Instructions for planting that come with bare root stock are useful for getting those particular trees started, but mention nothing about how even brand new trees need to be pruned after installation, and will need specialized pruning annually every winter thereafter. The same applies to rose, raspberry, blackberry (all varieties), grape, and to a lesser extent, fig, pomegranate, persimmon and several other fruit producing trees, vines and shrubs.
The problem with the stone fruit and pomme fruit trees is that they were bred to produce an unnatural abundance of unnaturally large fruits that are too overwhelming to sustain as they ripen, and too heavy to support. The others are in a similar situation, but are somehow able to continue to produce and generally support their own weight as they get overgrown and congested. Roses deteriorate and succumb to disease as they get congested.
This is why annual winter pruning is so important. Such pruning concentrates resources into fewer but superior fruits, rather than too many inferior fruits. It also limits and contains (closer to the main trunk and limbs) the weight of the fruit, so that limbs are not so likely to break as fruit develops.
These wimpy stems hanging vertically from the weight of the maturing apricots might be able to support the weight of the fruit, but the excessive fruit will be of inferior quality.
Some of us who enjoy gardening may not like to admit how useful the internet can be. There is a lot of bad information out there. There is also some degree of good information. It is impossible to fit much information about apples into just a few brief paragraphs. Therefore, the internet is likely the best source of information about the countless cultivars and specie within the genus of Malus.
The most popular apple trees produce the familiar crisp and sweet fruit that ripens anytime between late summer and late autumn, depending on cultivar. The fruit is quite variable. Some cultivars are best for eating fresh. Others are best for cooking or juicing. Some are very sweet, while other are quite tart. Each fruit is about the size of a baseball, but can be much bigger or much smaller. Crabapples are very small. Flowering crabapples make only tiny fruits that are eaten by birds.
The trees are quite variable too. Semi-dwarf trees can be pruned to stay low enough so that all of the fruit is within reach from the ground. Standard trees that grow in orchards can get as big as shade trees. All fruiting apple trees need specialized pruning each winter so that they do not become overgrown and disfigured, and to control disease. All apples bloom sometime in early spring.
Modern fruit trees have been so extensively bred to produce abundant and unnaturally large fruit, that most types are unable to support the weight of the fruit that they can produce each season. Without specialized dormant (winter) pruning to limit production, the weight of excessive fruit breaks and disfigures the limbs of the trees that produce it. Fruit becomes too much of a good thing.
Pruning not only limits the weight of the fruit; but it also improves the structural integrity of the limbs that must support it, and ideally, keeps fruit more reachable. Concentrating resources produces fewer but better fruits, instead of wasting resources on excessive fruits of inferior quality. Fewer stems that grow in spring are more vigorous and resistant to disease than more stems would be.
‘Stone’ fruits (of the genus Prunus) generally get similar pruning. However, peaches and nectarines produce such heavy fruit that they get pruned more severely than apricots, plums and prunes. Cherries and almonds are so lightweight that they may not need to be pruned at all. Cherries may be pruned for height. Since almonds get shaken from their trees, height is not so important.
Stems that grew last summer should produce fruit next summer. They should therefore be pruned short enough to support the weight of the fruit that they can produce (or what stems produced in previous years). For peaches, stems may need to be pruned to only a few inches long, even if the new stems are several feet long. Upper stems that get too high can be pruned out completely.
Apples and pears benefit from the same sort of pruning, but can be cut back even more aggressively, since their new stems tend to be more productive at the base. Crowded clusters of vigorous new stems can be thinned to eliminate the largest and most dominant stems. Stunted ‘spur’ stems that do not elongate more than two inches or so each year many not need to be pruned at all.
The ‘four Ds’, which are ‘Dead, Dying, Diseased and Damaged’ stems, are the first to get pruned out, even if they happen to be in the right places. There is just too much potential for problems later. Young trees that do not need much pruning now should be pruned for structure. Dormant fruit tree pruning is so important and specialized, that it is worth studying in more thorough detail.