Taming the wild

I recently became the steward of an unkempt mature apple tree. I cannot say this was completely down to luck. When looking at potential accommodation my partner inspects the house whereas I glance past to the garden. I spied the old apple tree and was hooked. It was overgrown but the thing is, you cannot buy established trees. They only pass from one steward to the next.

Established fruit trees are great; you get fruit straight away and their root system is extensive so additional water or fertiliser is not required, but to get the best out of a neglected tree it will need pruning.

Why prune?

As saplings, fruit trees are put through ‘formative’ pruning. Decisions are made as to the desired architecture of the tree based on the cultivar, its rootstock and garden context. Established trees already have architecture so we perform renovative or rejuvenative pruning instead. Our aims are fourfold: to enhance tree health and vigour, increase fruit production, ensure easy access for care and management, and create a beautiful tree.

Apple trees can broadly be placed into two categories; those that flower and fruit on spurs, and tip bearing varieties that flower and fruit on new growth at branch tips.

I don’t know what cultivar my apple tree is but all I need to know is that it’s a tip bearer. To the untrained eye, trying to identify whether your apple tree is a spur or tip bearer is a little tricky when the tree is bare, so be sure to take note during flowering and fruiting. This is vital as it will inform all your subsequent pruning decisions.

It is important to use the correct tools as any damage will take longer to heal in established trees. I use a sharp, clean set of loppers, hand saw and secateurs. Sanitary tools are critical.

Use a 70:30 ratio of water to methylated spirits solution or neat tea tree oil to remove fungal and bacterial pathogens. Never paint over or treat the wound of a tree. This antiquated approach inhibits the tree’s natural healing processes and increases the risk of disease.

The golden rule of all pruning is to remove any dead, dying, diseased or crossing branches. By doing so you are not only taking away possible entry points for disease but simplifying the pruning task by exposing the architecture of the plant. This makes life easier in the pruning stages, which require more thoughtful decisions.

A staged approach

A tree that has been let go will likely require canopy reduction. Pruning too dramatically will damage the tree as those leaves are its food source. Nor do you want to shock it into producing masses of new growth to replace what you’ve removed.

A general rule is limit removal to around 15% in any one prune during the cool dormant months. What we want is a steady, staged process conducted over two years to achieve our four renovative pruning aims. I reduce the density of the canopy, lower its height and remove vertical branches in favour of horizontal as these bear larger fruit with easier access. Creating a vase shape by removing inward growing branches and clearing the tree’s centre improves light and airflow, therefore improving fruiting and reducing disease.

In the early summer I reduce the crop to 24 apples, allowing the tree to concentrate its energies and produce larger apples. I use fruit protection bags to protect my chosen fruit from animals.

After the crop is harvested in autumn I will start preparing for the second year of my staged prune, where I’ll tackle the spreading canopy.

Written by Bryn Hutchinson, senior horticulturist, Blue Mountains Botanic Garden.