Summer Pruning – especially for Stone Fruit Trees

It’s a beautiful time to be pruning peach and nectarine trees in Adelaide, with sunshine forecast for days to come without being ridiculously hot – this means reduced risk of fungal disease for the trees and not too much sunburn unless you go in really hard. Pruning just after harvest means that the tree has an opportunity to put on some new growth that will bear fruit next summer, within easy reach for picking.

I like to keep most of my fruit trees to a maximum height of 3-3.5m, which means pruning them back to around 2.5m. It varies depending on their position and the other purposes they serve (like shading a sitting spot or lining a path). There are a few fruit trees that I’m growing to be taller so they can provide extra shade where we need it most – but I’ll compromise there by sharing crops with the birds, because putting nets over larger trees can be pretty unwieldy as well as unattractive.

Pruning can seem a bit daunting until you’ve had some practice – and there are many different approaches that work well for different people – so don’t stress, give it a go and find the way that best suits you and your situation. Here’s a few tips from a workshop which I presented last year.

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Stone fruit trees, pruned annually to a compact, manageable shape that offers high productivity as well as providing summer shade and easy access in a home garden.

SAFETY NOTES
● Exercise care when working with sharp tools, ladders, uneven ground and normal  gardening hazards such as spiders, snakes, sunburn etc. Extra care if children present.
● Take breaks, drink plenty of water, don’t overextend yourself or your tools.
● Beware of overhead power lines, falling branches, onlookers.
● Maintain tools so they cut cleanly and don’t jam.
● Work from ground level when possible, and if you have to use a ladder, ensure it is stable.

WHY PRUNE?
Fruit trees have survived and produced for millennia without human intervention, but we have several reasons for pruning:

(1) for shape – a strong framework of branches can support a heavy crop of fruit, and the tree can be shaped to a convenient size and shape for access, netting and harvest;

(2) for fruit – pruning deciduous trees while still in active growth promotes new fruiting wood to grow within reach;

(3) for beauty – to keep a tree tidy and attractive;

(4) for longevity – by removing diseased parts and reducing stress on a tree, it may remain productive longer.

UNDERSTANDING DECIDUOUS FRUIT TREES
Deciduous fruit trees are those that drop their leaves and become dormant for winter. Their branches (in most species) tend to grow upright, and the top bud on a branch is where the strongest growth occurs. This is called ‘apical dominance’. If this tip is cut off, other buds further down the branch have more opportunity to grow and to produce fruit. We can exploit this to make trees the shape and size that we want and to keep fruit where we can reach it. Dormant buds can also be encouraged into growth by training branches into a more horizontal direction.

WHEN
● Peach and nectarine trees can be pruned immediately after harvest (summer/early autumn), but avoid heatwaves in case of sunburn to freshly exposed parts of the tree. These trees bear on one-year-old growth, so the new regrowth after pruning can bear the next summer, keeping fruit within reach. If left unpruned, the tree grows to an unmanageable size.
● Apricots are very prone to fungal infection so best pruned when sap flow has slowed in April to reduce exposure to fungal spores. They fruit on a combination of old spurs (short stumpy twigs off main branches) and one-year-old growth.
● Apples, pears and cherries are spur bearers. Prune to encourage more spurs & remove excess upright growth. Thin out spurs when too closely spaced (older trees). Espalier for more fruit.
● Plums fruit on mature wood and Japanese plums also fruit on new wood. Prune after harvest.
● Evergreen trees such as citrus can be pruned at any time of year, but avoid pruning heavily before harvest or heatwaves. Pruning mainly to lift ‘skirt’ and remove dead wood. Citrus tend to fruit mainly at the outer canopy so a light prune all over maintains a compact fruiting area.
● Winter pruning of deciduous trees is useful for initial shaping of a young tree and for renovation of an older tree (removing large branches) when tree is bare, but note that regrowth may be more vigorous and less productive (follow up with summer pruning).
● Always prune in fine weather, with fine days following, for cuts to heal well.

WHAT TO PRUNE
● Consider the overall tree shape that you want for convenience, productivity and aesthetics. Do you need to walk or drive under it, stop it dropping fruit over the fence? Do you need to be able to net it easily to keep birds off? Is it too dense for you to reach the fruit & need better access? Do you want it to spread out to screen an ugly view or provide shade?
● Two basic shapes: central leader or vase. (Espalier if you want a 2-dimensional result.)
● Keep several main branches that have approx 45 degree angle from trunk – this
is a strong shape to carry a heavy load of fruit. Ideally these ‘scaffold’ branches are spaced about 10-15cm apart on the trunk.
● Fruit buds are more plump than leaf buds and are often clustered together in groups of 2-3. Leaf buds are where new branches will emerge from.
● Pruning a branch stimulates it to send out new branches, i.e. the fruiting area multiplies
● First remove dead or diseased wood, criss-crossing branches and spindly growth.
● Open up centre of tree for ventilation and light reduces disease and improves ripening
● Trim back most new growth by around ⅓ (or bring tree down to preferred height). Shortening thin branches makes tree sturdier (fruit is effectively heavier when further out on branch).
● Peaches and nectarines fruit on last summer’s wood, so branches that have fruited and that are no longer needed to form the shape of the tree can be removed.
● Apricots, some apples and pears bear on spurs and stubs. Thin out the spurs, leaving them about a hand-span apart, otherwise fruit gets squashed together as it grows.
● Grapevines – select canes to train as main branches and give them sturdy support. Trim laterals back to a few buds each winter: 6-10 buds for seedless varieties, 1-2 buds for seeded.

HOW TO PRUNE
● If converting a central leader to a vase shape, cut the main stem just above the selected scaffold branches.
● Generally cut to just above a bud that is facing in the direction you want new growth to go (usually outward facing). Note that several buds below this will also produce new growth, so see where they are pointing too.
● The exception to cutting above a bud is if you want a small branch to form a fruiting spur (apples, pears, cherries) – cut just below the bud to encourage a new spur and discourage vegetative regrowth.
● Make clean cuts, slightly angled for rain to run off (not flat top), ideally parallel to the new growth.
● If taking off a heavy branch, shorten and lighten it first, then undercut to prevent tearing, then complete final cut from above. Cut to the ‘collar’. Don’t leave stumpy branches as they are inclined to rot.
● Where several branches shoot out from a single origin (e.g. on plum trees with tightly clustered upright growth, remove middle one/s where possible to open up the angle between branches and reduce risk of trapping fallen leaves and fruit.
● Don’t cut all branches off at exactly the same height or the regrowth will collide.
● Clean tools at least between trees (or after each cut to be thorough)
● Paint cuts? Opinions differ. Some advocate Bordeaux mix, biodynamic tree paste, bitumen paint – others say painting the wound can seal in fungal spores instead of keeping them out, and that the best protection is pruning in dry weather and when sap flow is low. You decide.
● If a branch needs to be removed, best to remove it while small – easier on you and the tree.

TOOLS
● Secateurs (bypass) for twigs and branches up to finger thickness
● Loppers – branches around 2.5cm thick. May be geared or ratcheted for extra power
● Pruning saw for larger branches. I use for up to 5-6cm thick
● Chainsaw – heavy pruning of major branches only. Tidy up with hand tools.
● Sharpening tools, e.g. whetstone or diamond sharpener
● Cleaning and disinfecting e.g. methylated spirits, container, clean rags, oil

TOOL MAINTENANCE
● Wipe tools clean after use (scrub if necessary), oil blades to protect from rust (e.g. veg oil spray) and mechanism/spring (e.g. machine oil) to keep it working smoothly.
● Store in a dry place (sheds are often damp and tools may rust).
● Sharpen blades to their original angle as soon as they start to become dull & cut poorly. Sharpen only the bevelled side of the blade.
● Sharp tools make the job safer, easier and keep the tree healthier by reducing damage that would permit disease entry.

If pruning your fruit trees still seems daunting, home tutorials are available – ph 0410 636 857 or email nadjasgarden@gmail.com. 

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This entry was posted in fruit, maintenance, summer, trees. Bookmark the permalink.

2 Responses to Summer Pruning – especially for Stone Fruit Trees

  1. macmsue says:

    Thanks for the tips, I’ll be following your advice about pruning Nectarine and Peach trees.

  2. Joe's Connected Garden says:

    Excellent article Nadja!

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