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So why would you take to your avocado trees with a tree saw?

After reading a lot of detail on a web site based in the USA called "Avocado Source" I got thinking about avocado trees and why they weren't producing and what we could do to make them work better. It is clear that the evidence overseas is that as avocado orchards get overgrown, but particularly as the trees get bigger, the canopy to root ratio gets out of balance. That is to say that the canopy gets bigger than the root system can manage. Consequently the tree starts producing smaller fruit and more particularly on top.

If you think about an avocado tree, as it gets bigger it virtually creates a rain forest. If you've ever been to the rain forests you will know that the activity is on top of the trees and down below is a cool, heavily littered area where nothing grows. If you look at the trees in New Zealand that's what was happening in our orchard. It was cold down on the ground, there was no sun in amongst the trees and it was becoming colder and colder.

If you think about it even more you will realise that inside a large avocado tree there is a huge cavity of nothing. It's open air space with some branches sticking up supporting about 1 metre thick canopy at the outside. As the trees grow closer together there is no void or air between the trees. There is no sun down the sides of the trees and of course avocado trees won't produce unless there is sun.

Another reason that I made that decision was that I realised that the avocado tree was sending out long thin branches to try and reach the light and these branches would never produce fruit. Also if you look at rose bushes and grapevines they need pruning to make them produce and I don't think an avocado is any different.

So based on that information I employed a large tractor-powered hedge cutter with four saw blades. His instructions were to cut the western side off all my avocado trees which were fortunately in north-south rows. His instructions were to have the saw blade 2.5 metres from the base centre of the tree and to cut it on an angle to a maximum height of 6.5 metres. Overseas they make them a straight sided Christmas tree. In our case we allowed a bit more volume on the sides but we tilted the blades to maximise the trees at 6.5 metres.

The day was sunny and the hedge cutter started at the bottom of the orchard and it was one of the most stressful days of my life. He was cutting through branches up to 6" and 8" thick. It was banging and crashing, there was fruit flying everywhere and the whole process to cut 220 trees took 4 hours. The bill was approximately $1,000 and when he left I was left with a huge mess, branches everywhere and a lot of mess to clean up.

But what I'd done is taken away half of the canopy and I suddenly got light back in the orchard. There was sun on the ground and the void inside the tree had been transferred to between the rows again. What I propose to do is in two years' time to go to the eastern side of the tree and start cutting the side off that so that we have a symmetrical tree.

Given that we are heavily laden with fruit again this year that is going to be a very difficult decision but I am going to wait until the western side starts producing on the new growth and then I will be able to cut the eastern side from the trees.

Tidying Up

We employed a contractor with a hydro ladder and pole saw and he went around and tidied up the trees. We then had a ground person with a chainsaw cut a lot of the larger timber into firewood and cut down the bigger branches. We could then just push them back under the trees with a back-end loader and that worked very well.

Advantages

What are the other reasons I have the sides off my trees?
  • It will turn the trees into hedgerows and the sprayer will just have to go up one side and down the other. There should be less spray and thus a cost saving there.
  • As we know the tall hydro ladders are very expensive and there will be increasing costs here. By reducing the size and height of our trees we can stick to standard hydro ladders. It should reduce the cost of hydro ladders.
  • It should reduce the cost of harvest.
  • It should produce more fruit which are larger.
  • In two years' time when the western side starts to grow big again we are going to take the hedge cutter to it and keep the canopy with about 1 metre of greenery and anything that grows outside that will be cut with the hedge cutter.
  • Avocado trees put good fruit set on new wood.
I have my trees back under control.

So would I do it again? Yes, I would. I think it was a good decision. It was very scary but I think that the results are going to be amazing and already the orchard is looking much better than it did. We have the sun back into the orchard and it is looking like it is going to set another good crop this coming season, hopefully. I think that the problems in the avocado industry will be solved by the growers not by the scientists.

Summary

In summary, cutting the sides off my avocado trees was a huge risk. It's been proved overseas it's the right thing to do to control the huge trees. It's not for everybody but it suits my orchard.

I am going to manage the orchard with heavy pruning and I would consider just using a pole saw to prune the western side as distinct from a hedge cutter in the future. But hedge cutters will be used to maintain the size of the trees.

The most significant thing, I believe, is shifting the void - the area of air - from inside the tree to back to between the rows to where it belongs.


 

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