Winter Pruning

As a general rule, the best weather conditions for pruning occur during the first half of the winter. The weather is more settled over this period than later in the winter making it drier under foot and much more pleasant in the orchard. It therefore makes good sense to try and get as much pruning as possible done before the real nasty late winter weather arrives.

It is a good practice to set priorities for pruning based on fruit type, susceptibility to wet weather disease such as Silver Leaf and European Canker and the level of pruning required.

On mixed orchards which have both summerfruit and pipfruit, the tradition has been to tackle the summerfruit first then move into the pipfruit. There is good scientific as well as practical reasons for this approach. Summerfruit shed their leaves first which makes the pruning job easier and are very susceptible to Silver Leaf infection so should only be pruned when the weather is dry and settled.

Among apples there is good scientific evidence to support pruning smaller fruited varieties such as the Gala group as early as practicable in the pruning season because this identifies the buds which are being retained for next year's crop and enables the tree to channel its' reserves into those buds so resources are not frittered away on buds which will be pruned off later. This practice has been shown to increase potential fruit size.

At the other end of the spectrum, those varieties or blocks which are coming into their "off" crop year or are showing irregular cropping behaviour are best left until the early stages of bud break so it's possible to prune according to their flower load.

The Two Pass Approach

Many orchardists find the pruning job much easier to manage and control if they do it in two stages.

The first stage which can easily be done before the leaves drop is to go through the orchard with only a saw and focus on removing unwanted major branches and heavier side branches which have become too big for secateurs or loppers. If this job is done before leaf fall you have the added advantage of easily identifying the areas within the tree where better light penetration is required.

The second stage, which can be done later, is to focus on the detail work using secateurs to take out unwanted annual growth, weak fruiting wood and make sure the remaining fruit wood is adequately spaced out.

This approach also has the benefit in that the pruning task can be easily simplified into a systems approach so that those doing it do not have to concern themselves with complicated pruning techniques but instead can just focus on a few simple tasks which are easily understood.

I have one client who has developed this approach to the point where his skilled staff go ahead of the "detailed" pruners making the key branch removal cuts which require a good understanding of tree behaviour then relatively inexperienced pruners follow along behind tidying up the detail on what is left.

Reading The Tree

This is a key skill in achieving a quality pruning job and is a good approach to understanding tree behaviour.

The best way to learn how to read the tree is to identify branches or fruiting units which will show you how the tree has responded to particular pruning, or other husbandry practices. For example, if you want to know how a particular lateral growth or shoot will respond, look for a shoot that is one year older in a similar position on the branch, and if you want to know how it will look in two years time, trace its' behaviour back into three year old wood and so on.

Before you hook into the tree with the pruning, it's necessary to have a good look at the whole tree. Your thinking needs to start at the top of the tree and work towards the lower tree. Your first priority is making sure that the fruit bearing areas within the tree are exposed to at least 50% of available light. The second priority is to provide good worker access both through the orchard for machinery and also into the tree itself for workers.

The reason for starting your thinking at the top of the tree is that this is the area within the tree where much of the shading and excess growth problem occurs if the top growth is not well managed.

However, do not overlook "within branch" shading problems. This form of shading occurs when individual branches are allowed to develop dense and layered side laterals. It is usually the main form of shading problem in the lower tree.

The 3:1 Rule

This is a fundamental rule of pruning and can be applied to a number of critical pruning practices including:

1. Selection of branches and sub-branches
   The leader or main branch should be at least three times to diameter of any branch or side branch developing off it.
2. Opening up tree canopies
   Where branch removal is required for every three branches in the tree it's possible to cut out one branch without causing growth imbalance.
3. Shortening weak pendant branches
   As a rule, these branches can be shortened by up to 1/3rd of their total length without causing excessive vegetative growth response.

Work Rates

Over the pruning season, which lasts about 20 weeks, well motivated pruners using a systemized approach should be able to prune 10 to 15 hectares of semi-intensive orchard. The actual area pruned will depend on the condition of the trees to begin with and how kindly the weather treats us.

It is critical to complete heavier branch removal and have the debris mulched up before the spaying season starts in mid to late August.

Detailed pruning can be done up to the pre-bloom period, but once flowering commences should be finished as bee stings to be pruners then becomes a problem for people working in trees that are in bloom.