Formative pruning is carried out to enhance the branch structure, enabling the tree to be free from mechanical weaknesses and in an idyllic world free from any potentially hazardous features. This is achieved in practice by removing crossing branches, co-dominant/sub-dominant stems, dead, diseased and any other current or foreseeable defects.
This particular technique should be adopted when the tree is in a nursery to encourage the desired formation, ensuring that the wounds inflicted upon the tree are kept to a minimum. it is advised that newly planted trees are not pruned for 3-5 years, as it could have detrimental effects on both the tree hormones and development.
Trees are pruned for a wide variety of purposes many of which are not directly concerned with the risk of mechanical failure. There may be a desire to restrict the size of trees which are within close proximity to surrounding objects, along with other growth encouragement such as artificial shapes, flowering and fruiting.
Formative pruning should be part of a long term management plan, this will reduce the need to remove any large branches along with lower maintenance in the future.