We’re well overdue to get back into the pruning articles. Last winters pruning articles are proving quite useful. I’ve re-read them and gone around and given the peaches, nectarines almonds, currants, apples and pears a good prune but I’ve been holding off on the cherries and apricots until after I’d met up with an expert.
Marlborough grows great cherries as you can see in the photo above that I took at Cherryland last spring. Now it’s autumn and I’ve just spent a morning wandering around another Marlborough orchard with John Eaton. John has planted and pruned pretty much every crop that has been grown in the region in the last 30 years and now consults to orchard owners like Peter and Trish Taylor of Ryland Estate.
He showed me around Ryland Estate, one of only around half a dozen cherry orchards left in Marlborough. The cherries are grown in bags, buried in the ground. The bags restrict the root growth and vigour of the tree, channeling energy into fruit production and making the trees crop earlier than an open-ground grown trees.
The trees are planted close together and are still around 2.5m high at 10 years old which is a combination of the restricting affect of the bag and the shaping and pruning regime John has followed. This makes them easy to pick on short step ladders. Here at Ryland the whole orchard is enclosed in some serious bird netting but in a home orchard these little trees would be easier to net.
How to Shape Cherry Trees
One of the first things you notice about the cherry trees is their open, multi-leader habit and that comes with some tough love up front. As soon as the trees are planted they are pruned to around 1m in height. For the home orchardist this seems very harsh. You’ve just spent $35 on a nice little tree with a few leaves at the top, the last thing you think of doing is chopping it off to a 1m stick. But that is exactly what you should do. By taking the top out of your tree at this height after planting you will encourage a host of new side branches to grow that will form an open centered shape for your tree.
This open center keeps the air circulating around the fruit, reducing fungal disease and lets the light in to help develop fruit buds and evenly ripen the crop. If you plant your tree and don’t top the central trunk you will get an upright tree with dense growth and all the fruit at the top of the tree where you can’t reach it or cover it with bird netting.
The weight of the fruit will pull down these young branches naturally to ensure the open center and low height and you can also tuck branches under each other or prune to downward facing buds to encourage a less upright growth habit.
If you didn’t chop the top out of your tree as soon as you planted it all is not lost. John has pruned an orchard of cherry trees that had been left un-pruned for 7 years. The trees were 12m tall and had no live fruiting wood for the first 2.5m. He took the chainsaw to them at the top of the pruning ladder, removing as much growth above him as there was ground below him. As soon as light and air was let back in the trees came away again and started cropping on new growth at lower, more harvestable levels.
Another trick to encourage new growth at lower levels if a cherry tree has got away on you is known as “syncturing”. This is where you cut a narrow incision with a pruning knife around 60% of the trunk and do the same an inch or so above the first incision on the oppopsite side of the trunk. This forces the tree into a state of shock and makes it put on new growth below the wound. Don’t cut completely around the trunk or you will stop sap flow to the upper growth of the tree.
Cherry trees are grafted onto different root stocks, the most common being Colt which produces a 3-5m tree and does well in a wide range of soils. You will see the graft on your new tree and you want to ensure you don’t shorten the central leader below this point when you chop the top out.
How to Prune Cherry Trees
One the main framework is established, John tends to work with the tree when pruning. Any growth going straight up gets removed. Likewise any growth in the middle of the tree that is going to restrict light and airflow. Branches coming off leaders are thinned so they don’t overlap and shade adjoining leaders and branches. Each of the main leaders is kept quite clean and sparse. Any branches left on are well spaced, tend to be nearer the end of the leader and pointing outwards, leaving the middle of the tree nice and open.
A tree may have 5 or 6 main leaders that are tipped at around a meter and are eventually replaced with other leaders. John looks 2-3 years ahead when pruning and selects replacement leaders, tucking them under other branches and growing them on until required.
Cherry trees fruit best on 2nd and 3rd year wood. New growth doesn’t fruit and you will see the difference between fat clusters of fruiting buds on old wood and thin pointy leaf buds on new wood. Fruiting buds are a bit like spurs on apple trees, they will carry on fruiting for several years so care when harvesting your cherries can preserve these fruiting buds for next season.
John likes to prune at this time of year, after the harvest but while the leaves are still on the trees. His experience is that if you prune in winter when the tree is sparse you don’t see how the leaf canopy shades the branches and you can under-prune. He prunes as much as a third of the tree out each year without damaging the crop. This keeps it open and encourages new growth.
He will only prune if the forecast is for 24 hours of clear weather due to the risk of spores from diseases such as bacterial blast and silver blight being carried on damp air. And any cut over the size of a 50c piece is painted with an anti-bacterial pruning paste to seal it against infection.
What kind of yield will a well-pruned cherry tree give you?
These little trees, restricted to 2.5 m in height, are still capable of cropping 10 kilograms of fruit a year per tree. Left unrestricted a large tree may crop up to 20 kg of fruit but whether you can reach it to pick it is another question.
Sweet cherry trees come into full production around 6 years of age. In a home orchard they will crop well for 15-20 years before they need replacing. If you’ve got the space, I’d plant a new cherry tree every 10 years to ensure you’ve always got plenty of cherries. Left to their own devices cherry trees will live for a long time but perhaps not be as productive.
How to Prune Apricots
Apricots have a similar pruning regime to cherries. They like an open centered, multi-leader tree. The less vigorous branches tend to produce more fruit. Any vigorous branches going straight up should be removed and you should aim to take about 30% of the tree out each year. Late summer pruning after harvest is also a good way of reducing the vigour of the tree.
Pruning back to downward facing buds also reduces the vigour. The same rules for pruning cherries apply. You’re aiming to have a mixture of old wood with new growth coming on. Apricots will start producing after 4 years and will happily go on producing for 30 -40 years.
Getting the Right Apricot for Your Garden
A lot of people struggle to grow apricot trees in the home garden. But it’s just a case of getting the right variety and rootstock for your situation. Good apricots for warmer climates include Sundrop, Katycot, Tomcot, Royal Rosa, Robada, Trevatt, Newcastle and Clutha Gold. Moorpark, a traditional favourite, needs good winter frosts to produce well.
Apricots are most commonly grafted onto golden queen peach rootstocks which don’t like heavy soils or wet soils. Apricots grafted onto plum rootstock myroballum are harder to come by but produce a more vigorous tree in heavy or wet soil. Individual varieties of apricot are also vigorous or not. Sundrop and Newcastle are, Katycot and Tomcot aren’t.
I planted 5 apricot trees around 10 years ago in heavy clay soil. One was grafted on plum rootstock the photo on the left below shows it has thrived. The other 4 were grafted on peach root stock and just sat there not growing despite getting exactly the same treatment and being right next to each other. The middle photo below shows you how they looked at 6 years when I pulled them out. The lesson is – if you’re on heavy soil don’t plant non-vigorous apricot varieties grafted on peach root stock!
Pests, Diseases and Weather.
There are a couple of nasty diseases and a pest to watch out for on your cherry and apricot trees. The first is bacterial blast which you can identify by gummy globs of goo and cracking of bark. Don’t confuse cicada damage with bacterial blast. Cicadas can chew the bark and it looks similar. If you find it on a tree cut out the affected branch and burn it or remove it from the orchard. A copper spray in early winter will clean it up.
The next bacterial disease is silver leaf which spreads in damp conditions through an orchard. Which is why you only prune in warm dry weather. Leaves will show a silvery white sheen, fruit doesn’t colour up and it eventually kills the tree if left untreated. To get rid of silver leaf you must go back a foot past the last symptoms and cut the branch off. Remove the wood from the orchard. Spraying the tree with Jeyes fluid and meths is a traditional method of cleaning up any silver leaf remaining.
Always wipe your pruning blades with meths between trees to reduce the chance of carrying disease to another tree. Here are some photos of blast and silver leaf from my orchard.
The final pest that can bother your cherry trees is the black aphid which can really damage the tree. Spraying a winter oil on trees at the end of winter before bud burst is a good way of suffocating any of these sucky pests that are wintering over on your trees.