Pruning and training techniques for young trees

Shoot pruning

Ideally newly planted trees should fill their allotted space at planting and, where this is the case, very little pruning is required. If trees are much smaller than the space allowed, early yields will be compromised as growth will need to be stimulated and this will be at the expense of crop. Growth should be encouraged by a combination of pruning, removing all fruit and applying extra nutrients.

• One of the potential problems with planting very large, well-feathered trees is the tendency to develop bare wood on branches.
• This is worse when trees are planted in the spring in cold soil conditions and/or when the tree undergoes a period of stress, especially during the early summer period.
• Where a well-feathered tree is planted and fills the space at planting, the leader should be left unpruned. It will then naturally develop short fruiting laterals and sufficient extension growth to achieve the required height without becoming too dominant.
• Only where the feathers are too few or too weak and do not fill the space should the leader be pruned.
• In severe cases, prune back to one bud above the top feather to give maximum growth stimulation to the feathers which also should be tipped lightly. Otherwise tip the leader approximately 20 -25 cm above the top feather.
• Six to eight of the optimally positioned feathers, if present, should be retained and the lowest and other unneeded feathers removed.
• Remove strong upright feathers which have narrow branch angles and may compete with the central leader.
• With scion varieties, which have a tendency to produce bare wood later in their life, it may also be wise to tip the retained feathers.
• Severe pruning of either the leader or the retained feathers will generally delay flowering on the trees and encourage strong vegetative growth.

Shoot bending, training and brutting

Horticulturists have known for many centuries that bending shoots of apples towards the horizontal reduces the vigour of extension shoot growth and stimulates increased production of floral buds in the following season. The quality of these flowers is also improved.

• With apple scion varieties that produce laterals with upright growth habit, the retained feathers should be bent down towards or below the horizontal and secured in this position.
• Where the upright growth habit is not too severe and the stems of the feathers are not too thick, this may be achieved using small weighted pegs.
• Alternatively, the young branches are secured using string attached either to the support stake or to W clips pushed into the soil.

Partially breaking small laterals on young trees (sometimes called brutting) can also reduce shoot growth and stimulate increased flowering on these shoots:

• Tie down lateral growth towards the horizontal or below this angle on very strongly growing varieties.
• Partially ‘snap’ short laterals formed from the central leader, so as to reduce shoot growth and encourage flowering and fruit set.

Root pruning or root restriction

Research in the USA and at East Malling Research has shown that pruning the roots of young trees, using a deep spade or root pruner reduces subsequent extension growth and increases the production of flower buds (Webster et al., 2000, see Further reading).

• Unfortunately, if supplementary irrigation and nutrition is not applied, fruit set per tree is not always increased and fruit size at harvest is generally reduced.
• Root pruning is not recommended for use on young newly planted trees.

Planting trees within root restriction membranes buried in the soil has similar effects to root pruning, although effects on final fruit size are usually not so severe.

• The most favourable responses have been achieved using membranes which only partially restrict apple tree root growth.
• Root restriction by planting trees within woven membranes is not thought to be economic, currently, under UK conditions.