Creating a good frame
There are five pruning strategies within the canopy that are aimed at different stages in the life of the orchard. This pruning is done by hand.
- Initial heading at planting will balance top growth in relation to the root system. Branching should not be allowed on young trees until they reach a height of 50 to 60cm. Young trees should have 20cm of straight trunk above the bud union before branching. Heading at this height will reduce the amount of time spent on skirting in later years.
- Main scaffold branches should be staggered as too many branches initiated in one spot can cause crowding and weakening in later years. Aim to maintain about eight main scaffold branches as dominant limbs, once established. Prune subsidiary shoots from the main scaffold branches to reduce competition. Select the more horizontal shoots as fruiting wood.
- Thinning out of branches as trees age allows light to penetrate into the centre of the tree. This helps to maintain fruit production inside the canopy, as well as on the periphery.
- Chunk pruning on older trees allows light into the center of the tree. In hedgerow plantings, remove a whole scaffold limb on opposite sides of alternate trees. This allows access for pickers into the inside of the tree. The extra light also improves the colour of internal fruit. Some growers remove a large scaffold branch from a different section of the tree every two to three years. Where trees are more widely spaced, a large scaffold branch on the north side of every tree is removed to improve access and to increase light penetration.
- Skeleton pruning is normally a last resort with old trees to get a few more years from them. Prune in autumn and cut back all shoots, leaving only the main scaffold branches. The scaffold branches should be painted with watered-down white acrylic paint to protect the bark from sunburn until the tree refurbishes itself.
Skirting (skirt pruning)
Skirting is the removal of branches and limbs which hang down to the ground. It should be done as soon after harvest as possible.
Skirting of Valencias and summer navels is more difficult as the trees are carrying two crops. Some crop loss is inevitable whenever late varieties are skirted. Skirting in October or November after fruit set is probably the best option.
Mature trees should be skirted to a height of at least 75cm. This allows for branches dropping lower when fruit develops. Machine skirting is quick and easy.
Skirting provides the following advantages:
- better air movement under the trees
- easy application of below-tree herbicides and fertilisers
- reduced access into the tree for insects and pests such as Fuller’s rose weevil and snails
- clear throw of irrigation water from mini-sprinklers and ease of checking on the operation of mini-sprinklers and drippers
- no splashing of soil-borne fungi into the canopy from rain or irrigation
- better access when harvesting
- prevents lower set fruit from hanging in the dirt
- required practice as part of the market access protocol for some export markets.