Recent mild temperatures and the relative lack of chill nights have delayed the onset of leaf drop and tree dormancy this year. Nevertheless, according to the calendar, we are well into the winter pruning period. So a review of method and approach seems useful at this time.
'Bramley's Seedling' is an extremely vigorous variety with large diameter fruit. These are important considerations in pruning your Bramley orchard to best effect. Remember that only five to eight per cent blossom set can result in a full apple crop, so in spite of the generally disappointing yields across the county in 2009, please don't be reluctant to thin unproductive timber from your trees. The poor results this year were due to appaling pollination conditions, not a lack of flowers!
You may be tempted to start this winter with the most vigorous and challenging of your orchards. Although this is understandable, there is an important reason to resist this approach. It has been demonstrated that very vigorous fruit trees should be pruned as late in the winter season as practical, to minimise the degree of 'reaction' wood or water-shot growth that arises.
This is because the reserves of nutrients and stored energy (starch and sugars) from the previous season are held in the tissues of the root system, trunk and large limbs. These energy reserves only begin to move back into the outer branches and twigs from early- to mid-Spring. If you prune your most vigorous orchards in early winter, you haven't removed any of this latent energy and the vegetative response can be strong.
If you delay pruning these strong trees until early spring, you will be taking some nutrition with the wood you remove and thus weakening the tree's extension growth (but not it's fruiting potential!).
The first priority in winter pruning is always the removal of congested, crossing and diseased or damaged branches. It takes a little imagination and experience to 'picture' the trees in full leaf next season, but this is a useful exercise as it helps you to identify the densest sections of older trees, where shading will certainly become a problem; restricted light levels in the tree canopy always leads to poor fruit set and inferior apples.
Do consider the serious but worthwhile challenge of reducing the height and spread of established trees on M111 or M106 rootstocks. This is a project to execute over three or four winters, and it will pay dividends by rejuvenating the orchard, especially where dense canopies with small fruit have been a persistent problem.
Regardless of rootstock type, a larger apple tree will lock up more of its dry matter (i.e. energy and growth) in the leaves and timber than a small tree. This always happens at the expense of fruit growth and development.
The advantages and convenience of dwarfing rootstocks, planted at high density are well known with regard to light penetration, spray applications and picking.
The advantage extends to the relative ease and speed of pruning such trees, but they still require some careful attention, even in their formative years. You must be ruthless in sacrificing any feathers or young branches with a narrow branch angle i.e. those growing almost vertical from the trunk. Also remove any branches with a girth as thick as the trunk - the sooner the better.
These will always be too competitive and will dominate the frame of the tree, causing lopsided habit, poor stability and shading of any limbs beneath.
The aim of your pruning on M9 or M27 Bramley is to maximise the cropping framework per tree while limiting the height, so 'heading back' the leader is an essential part of the annual winter schedule from the second winter after planting.
