So last week on the blog we gave you an introduction to the tools and terminology of pruning. This week we’re going to cut to the chase (literally) and talk about pruning peaches, nectarines and almonds, collectively known as “stone fruit”. Just after harvest is the perfect time to prune stone fruit because the days are dry and warm, and there are no fungal spores flying around on damp air.
You can also prune stone fruit in winter, when they are dormant if you didn’t get around to it in summer. But if you’re going to prune in winter, make sure you do it on a warm, dry day and seal every cut with pruning paste so that disease doesn’t get in. We’ll talk about peaches and nectarines first and then we’ll cover a few differences for pruning almonds at the end.
The first thing to know is peaches and nectarines produce fruit on first-year wood. The wood that fruits this summer will not produce fruit next summer. So you need to prune to stimulate the growth of new fruiting wood. New growth this summer, will bear fruit next summer. If you prune every year, your tree will always have plenty of new fruiting wood coming on and you’ll get regular heavy crops of peaches and nectarines. If you don’t prune your peach and nectarine trees every year, you’ll get some new growth that will bear fruit, but as the tree gets older it will be at the extremities of the branches, often up high.
By pruning every year you can keep the new growth coming on evenly around the tree at a more harvest-able height. I’ve visited elderly peach trees in commercial orchards that are still only 3m high, but have loads of new wood within easy picking height because they’ve been pruned regularly. Shaping a young tree can help you keep the height down and improve airflow around the tree. The vase shape is the most popular for peach and nectarine trees because it lets plenty of light and air into the center of the tree, which ripens the fruit and reduces the chances of brown rot. Most stone fruit trees are sold with a central leader and a few lateral branches, (read last weeks blog if these terms are baffling you). To turn this into a vase shaped tree, plant the tree as it is and remove the lower limbs to around waist height for ease of mowing and weeding around. Remember to seal each cut with pruning paste as you go. Then choose 3 to 5 lateral branches and tie them down with string and metal ground pins so they radiate out around the trunk at even intervals. This tying down for the first season helps train these main branches to grow out and not up. Don’t tie down too tightly or the branches will snap in the wind. Use loops against the branches so they have room to grow. Note: You can let it grow for 2 seasons before chopping the top out if it isn’t big enough to choose the branches for your vase shape in the first year.
Once you’ve established your framework you prune back to this each year. It is hard to over-prune peaches and nectarines. The basic technique is to thin out and shorten branches to keep the new wood low for easy fruit picking. You should aim for an open core framework of main branches with lots of thin, new growth coming off them. A pruned peach or nectarine tree can look like it’s had a bad haircut but remember you’re pruning to promote new growth, not shaping it to be a feature tree. In addition to pruning your peaches and nectarines for new growth, you should also remove overlapping branches, water sprouts, diseased branches and any branches growing too close together. See last weeks blog for definitions of these fruit tree pruning terms.
One final tip – when you want to maintain a certain shape, eg. low outward growth away from the center of the tree, you just prune back to a bud that is pointing in the direction you want the new branch to grow. Some buds point down, some point up, some point sideways and you get good at noticing this when deciding where to make your cut. If you have a really old peach or nectarine tree that you’re trying to re-invigorate our advice is to give it a couple of years but if it hasn’t produced a lot of healthy new growth in response to your pruning then it is not worth persevering with. Peach and Nectarine trees are not as long lived as other fruit trees like plums and apples. If you get 20 years out of them you’re doing well.
Pruning almonds is very similar to pruning peaches and nectarines, the only difference is frequency. Almond trees are longer lived trees and they will produce fruit on older wood for up to 4-5 years, with fruiting spurs like apples and pears. So there is no need for vigorous annual pruning to continually generate new fruiting wood.
The same rules for shaping and pruning the tree do apply, just not as often. When the tree is 3 or 4 years old and you have established the open vase shape that you want, you can limit your pruning to every second year and focus just on removing water sprouts, overlapping and diseased branches and thinning out around 20 – 30% of old fruiting wood. You can also allow a second tier of scaffolding branches to grow off your main vase limbs to generate more of a framework to carry fruiting wood, just try and maintain an open center. Almond trees are also more susceptible to gummosis and canker than other stonefruit so be sure to prune on a sunny day and paste the cuts with anti-fungicidal paste as you go. Also remove any “mummies” from the tree and ground before you start. These are dried fruits from the previous year that weren’t harvested and they can house fungal disease spores.