Fruit trees are grown in a variety of shapes, sometimes to please the eye but mainly to encourage fruit production. The form or shape of fruit trees can be manipulated by pruning and training. Shaping and promoting a particular tree form is done to establish the plant in a particular situation under certain environmental conditions, to increase fruit yield, and to enhance fruit quality. For example, pruning a tree to a pyramid shape enables trees to be planted closer together. An open bowl or cup form helps sunlight penetrate the canopy, thus encouraging a high fruit yield whilst keeping the tree short and accessible for harvesting. Other shapes such as cordons, espaliers and fans offer opportunities for growing trees two dimensionally against walls or fences, or they can be trained to function as barriers.
Forms
Some of the following fruit tree forms require training by tying the branches to the required form. Most require pruning to retain the desired structure. However, not all types of fruit tree are suitable for all forms; apples and pears do well as cordons and espaliers, for example, whereas cherries are more suited to the fan form.
Bush
An open-centred crown on a short trunk of less than. This is a traditional and popular form for apple trees. Bush trees are easy to maintain and bear fruit at a young age. Final height is between and, depending on which rootstock is used.
Standard
Larger than the bush form, with trunks of or more. Standard trees can reach a total height of. They eventually produce high yields but, being large trees, are not easy to maintain.
Pyramid
Similar to the bush form, although the main leader shoot is allowed to maintain its dominance, resulting in a pyramidal shape.
Single-stemmed trees planted at an angle, with fruiting spurs encouraged to form along the stem. Any side branches are removed by pruning. Cordons take less space and crop earlier than most other forms, so more varieties can be grown in a given space, but yields are smaller per tree. A specialcordon set-up is the Bouché-Thomas system.
Espalier
A central vertical trunk with three or four horizontal branches on each side. A special espalier in this group is the LePage-system.
Fan
A short central trunk with several radiating branches growing from the crown.
Step-over espalier
Espaliers with just one tier of horizontal branches 30 cm from the ground. These make a novel and productive border for a vegetable plot. A study on orchard mango trees in Nelspruit, South Africa, compared open vase, closed vase, central leader, palmette and standard pruning systems and recommended a modified pyramid, somewhere between a central leader and a closed vase system, for high-density mango orchards. The study also evaluated both post-fruit-set and post-harvest pruning, indicating that late mango cultivars benefit from pruning while bearing in late fall, while early cultivars may be best pruned immediately after harvest.
