Training helps develop a strong framework that supports a good crop, with optimal fruiting wood continually being renewed. Training and pruning let light into the tree to maximise photosynthesis and allow air circulation which reduces the risk of disease. A well-shaped tree is easier to spray, harvest and thin out.
Different fruit species produce fruit on wood of different ages. To determine which type of wood to prune, you must distinguish between leaf buds and fruit buds.
Leaf buds are single, thin and pointed, growing close to the stem. Fruit buds are plumper and often occur in clusters of flower buds capable of developing into fruit.
Traditionally pruning is done during winter dormancy. However, summer pruning is better for trees which need large branches removed, including those susceptible to gummosis such as apricots and cherries.
Training occurs between the first and fourth year. Once the framework is established and fruiting begins, maintenance pruning is introduced.
In both training and pruning two cuts are used: heading back and thinning out. Heading back means shortening a branch or shoot to encourage branching. Older wood is headed back to an outward growing lateral. Thinning out means removing entire shoots or branches back to a lateral branch, scaffold branch or trunk.
Use clean, sharp, good quality tools. Prune in dry weather to prevent diseases spreading. Regular moderate pruning is better than infrequent heavy pruning. Make close, clean cuts because stubs encourage decay and canker in the parent branch or trunk. Undercut branches to prevent bark tearing. Seal cuts with fungicide.
A central leader tree has one main trunk (the 'leader'). Branching from the leader begins 75–100cm above the soil surface.
In the first year select three or four branches to retain as a scaffold whorl. Scaffolds should be uniformly spaced around the trunk and set at 50–60cm vertical intervals. In between, the areas where branches are removed allow light into the centre of the tree.
A central leader tree is pyramidal, with the branches of the lowest scaffold whorl being longest and the higher scaffold whorl branches becoming progressively shorter to allow maximum light penetration.
Here the central leader is removed at an early age, leaving the middle of the tree open with three to five major limbs around the trunk. Light can then penetrate the centre, minimising the shading problems which otherwise are prevalent in high vigour trees. Saplings destined for vase training may be bought branched or unbranched and, depending on their form, require different planting methods.
At planting, set the tree with the graft union at least 10cm above the soil surface. As the buds swell, the unbranched tree (the 'whip') should be headed back to 75–85cm above the soil surface. Buds 15–25cm below the cut will form branches.
With trees which are already branched remove very low branches. If there are three or four uniformly spaced branches around the tree select these as leaders. Head the tree back just above the highest selected leader and remove any other branches. If there are less than three leaders, remove side branches and cut the tree back to a whip.