Aug 162008
 

Photo © Bulleen Art & Garden

Fruit trees require pruning to maintain the health and vigour of the tree, as well as to encourage fruit production. Regular pruning opens up the canopy allowing greater air circulation and more light into the canopy. An added bonus is making the fruit easier to pick each year by restricting the size of the tree.

As long as pruning cuts are made in the correct position and cleanly, the plant will heal. Using special paint to seal the cuts is not usually necessary if the cuts are made correctly with clean pruning equipment. Always use pruning equipment appropriate to the size of the branches you will cut. The most commonly used pruning tools are secateurs, loppers and pruning saws. When tying up stems, use soft flexible ties and allow for some movement of the stem. Remember to regularly check and remove ties, as these cause significant damage to plants if they are left on unchecked.

Position of the pruning cut.

When making pruning cuts on smaller stems and branches, the position of the cut is just above a node (see diagram right). A node is where a bud, leaf or stem emerges from a branch. The internode is the space along the branch between the nodes. If the cut is made too far into the internode, then the branch usually dies back to the node. This area of die back is a potential entry point for disease.

Note: The angle of the cut is not as important as getting the position right. Ideally, the cut should angle slightly away from the bud so that water is directed away from the bud. Do not cut on a sharp angle as this makes a large wound and may damage the bud.

When pruning main branches, the cut should be positioned so that the branch – bark ridge and the collar are not damaged. The branch – bark ridge can be seen on most trees. It is the ridge of bark on the top side of the attachment point where the branch is attached to the trunk. The collar is harder to see, but it is the swollen area underneath the attachment point of the branch to the trunk. Even if you cannot see it, the collar is still there and should not be damaged. The pruning cut should be made just outside this area.

If you leave a large stub, then this usually dies back and is an entry point for disease. Undercutting a branch before cutting is recommended, particularly on larger branches, as this prevent the bark tearing and damaging the branch collar. Avoid damaging the bark, as this can cause significant damage to the tree and provides a potential entry point for disease.

Photo © Bulleen Art & Garden

To encourage branches to shoot below another branch without pruning off any of the above growth, a small nick can be made through the bark just above a bud. This is called suturing and is a useful technique to encourage branching where there is a gap in the canopy.

What to prune.

In addition to encouraging fruit production, fruit trees require regular pruning to remove dead or diseased branches, remove branches that cross over, keep the centre of the plant un – cluttered, and thin out the fruit.

Thinning Fruit

Thinning fruit is usually done to prevent fruit drop, broken branches and biennial cropping, and is done at the flowering stage or when the fruit is very small. Thin clusters, leaving 2 to 3 fruits in each cluster, and space out fruit along the branch 15 to 20 cm apart by pinching out all flowers or fruit in between.

When to prune.

Most deciduous fruit trees and vines are pruned in winter, usually late June or July. Apricots should be pruned either early in autumn when they still have leaves on, (this is preferable), or after flowering in spring. This is to prevent the disease gummosis. Pruning evergreen fruit trees such as citrus and some of the tropical fruit trees such as guavas should be done late spring if it is required.

Spraying

Peaches and Nectarines are susceptible to a problem called Peach Leaf Curl caused by the fungus Taphrina deformans.  To prevent this trees should be sprayed with a fungicide when the buds are swelling but before they have opened. If it rains after spraying, then you will need to spray again. The most commonly used spray for this purpose is Copper oxychloride. Once the tree shows the symptoms of the disease, it is too late to spray. Where the disease has been difficult to control in previous seasons, a program of three sprays is recommended. The first spray should be applied in autumn, at leaf fall. The second spray should be applied immediately before budswell at the late dormant stage, and the third spray about one week later at bud swell. There are signs posted in the nursery, and on the website when it is time to spray.

Fruit trees may also be sprayed with White Oil or Pest Oil after pruning, to smother scale and the eggs of other insects, which may be over-wintering in the crevices of the bark.

Pruning methods.

Peaches and nectarines.

Vase shaped pruning is the most widely used pruning technique, which aims at developing a strong framework of branches. Fruit is produced on the previous year’s growth.

First year pruning forms the framework branches for the tree.

Step 1 – The main branches will have many small twiggy branches, called ‘feathers’. Cut back the main branches back by approximately two thirds to an outward facing ‘feather’.

Step 2 – Prune back the ‘feathers’ to an outward facing bud.

Step 3 – Prune off all ‘feathers’ growing in towards the centre of the tree.

Second and third year pruning continues the framework of the tree, by selecting and pruning laterals back. Once the framework branches have been selected, then yearly pruning is used to remove dead or diseased branches, remove any branches growing in towards the centre of the tree, and to space and shorten the fruiting branches coming off the main laterals.

Some people recommend pruning dwarf peach trees in summer.  This way you can easily select growth for next season’s crop.  When you look at your tree, there will be three types of wood:  Last years fruiting wood, this years fruiting wood (has fruit on it) and next years fruiting wood (growth that is fresh, and has no fruit on it). Peaches grow on the lateral growth made in the previous season, so leaving alone branches bearing fruit this season, prune to remove the previously fruited old wood, and carefully thin and space out the new seasons fruiting wood which will bear fruit next year.

Pears and apples

These are usually pruned to encourage the formation of fruiting spurs, from which the fruit is produced each year. The fruit is produced on at least second year old wood.

The first year of pruning forms the structural framework for the tree.

Step 1 – The leader, (main central upright branch), is pruned. However, if a raised canopy or an espaliered tree is desired, the leader should not be pruned.

Step 2 – Layers of lateral branches called scaffold branches should be selected approximately 45cm apart. Prune off all other laterals at the trunk.

Step 3 – Prune back the scaffold branches to approximately 20cm.

Tree growth should be encouraged in the second and third years, with minimal pruning required. The only pruning should tidy the framework and remove any damaged branches.

By the third year, any laterals that are growing out horizontally should develop flower buds along the length of the branch. Laterals that are growing vertically may be gently weighted at the ends, (pulling the branch into a more horizontal position), to encourage flower bud development along the laterals. Spurs develop from these flower buds along the laterals. These should be pruned to the second bud and then to the first bud the year after. The fruiting spurs become more un productive as they get older, so subsequent pruning should remove old spurs and encourage the formation of new spurs.

Cherries

These require little pruning from year to year. The first and second years growth will form the framework of the tree. Usually, shortening the main branches by half to two thirds to an outward facing bud is all that is required. Fruiting spurs will develop along the branches, from which the fruit is borne. Thereafter prune out any broken branches, or those that cross over other branches. Old un – productive spurs may be pruned out and new spurs created by pruning back a new shoot to the main lateral.

Plums

The first few years of pruning are used to form the framework branches of the tree. Therefore, initially the pruning is the same as for peaches and nectarines. Plums also produce fruiting spurs along their branches, as well as quite vigorous growth from the tops of the branches. This vigorous growth should be checked by pruning out all the top growth on each branch, leaving a single branch as a new leader. This new leader may be shortened to encourage the production of more fruiting spurs along its length. The fruit is borne on wood that is at least two years old, similar to apples and pears.

Apricots

These should be pruned in early autumn when they still have leaves on, or in spring after the flower buds have opened. This is to prevent a disease called gummosis entering through the pruning cuts.
Apricots fruit on short sprigs along the main branches. These need to be renewed after four years by selectively pruning to a new sprig below the sprig that is currently producing.

In the first year prune to the initial set of sprigs.

Step 1 – The un-pruned tree will have bunches of short twiggy growth (sprigs) roughly half way up the main branches. This is called the foxtail. Initially each branch should be pruned down to just above the foxtail area.

The second and third year’s pruning, shortens the main branches, but do not prune off new sprigs that have been formed until the fourth year when a healthy new sprig is chosen to replace the current one.

Apricots will also develop spurs along the branches, which will also bear fruit.

Almonds

Almonds bear fruit similarly to Apricots on sprigs and spurs. They do not require much pruning from year to year. In the first year select framework branches and prune lightly. Commercial growers of Almonds prune off one main lateral branch each year on mature trees to encourage greater vigour.

Other deciduous fruit trees only require initial framework pruning and the removal of broken or crowding branches.

Citrus

Citrus do not require much pruning, except removing dead or damaged branches. However, citrus may be pruned to restrict the size of the tree and make it easier to harvest the fruit. Citrus do respond well to pruning, even heavy pruning, which is sometimes required due to Citrus Gall Wasp in the local area. The tree may take a few seasons to resume normal fruit production after heavy pruning, as most of the energy will go towards leaf and stem growth at the expense of fruit production.

Tropical fruit trees

These generally do not require pruning, however, any frost damage should be pruned off in late spring. Apart from this, removal of dead and diseased wood is the only pruning required, as well as any pruning to improve the general shape of the tree where required.

Berries

Raspberries, Loganberries, Youngberries and other bramble type berries, grow on long canes that shoot from the base. These are best grown on rows and given a wire support. The first years canes are vigorous and are best left unpruned or tip prune in winter to a suitable length (approx. 1.5m). These canes produce short laterals the following spring on which the flowers and fruit are borne. The following winter prune these canes to the base as they will produce little or no fruit the following season. This encourages new canes to shoot up and produce fruit. Some of the more vigorous bramble type berries may be grown up posts and over wires, but the basic pruning remains the same.

Blueberries are a suckering shrub that fruits on one two and three year old laterals. After this the branch becomes unproductive and may die back. Therefore pruning takes out these older suckers as well as any weak growth and encourages new healthy suckers.

Gooseberries produce fruit on both one year old wood and on fruiting spurs, and currants produce on fruiting spurs. Both need initial pruning to form a shrub with a main trunk around 30cm and four to eight lateral branches. Each of the laterals should be tip pruned. These lateral branches will remain productive for around 5 years, after which they should be pruned out so that a new lateral can take its place. Keep the bush open in the centre and prune to outward facing buds, or for currants to an upward facing bud.

Grapes

There are two methods usually used for pruning grapes, cane pruning or spur pruning. Grapes grown commercially for wine production or fruit are usually spur pruned, however, most home gardeners train the vines over a structure and so cane pruning is used.

Cane pruned Grapes -This is used for Sultana grapes as they produce fruit on the current season’s growth and on one year old wood. This technique can also be used on other grapes where they are to be trained over a structure, such as a pergola.

The young plant will have one main stem from which several canes (long stems) emerge. Select up to four of the healthiest canes and prune all others back. Wind these canes around each other and tie up to the support. Each year prune side shoots that develop back to these main canes.

Spur pruned Grapes – This is the method usually used in vineyards. Grapes are produced on current year’s growth from permanent spurs. The young plant will have one main stem from which several canes emerge. Select the strongest of these as the framework canes. Usually two canes are chosen, one trained to the right and one to the left of a support. Tie these horizontally to the wire or support. Laterals will shoot from the two framework canes. Choose evenly spaced laterals on the top of the framework canes and prune back to one or two buds. These will become the spurs. Prune out any excess laterals that are crowding the canes. Each year prune back the spurs to the first or second healthy bud.

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