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Central leader vs. open centre

Posted by David Maxwell 
Central leader vs. open centre
April 26, 2015 09:59PM
I note that the Brits consistently train their semi-dwarf and full-size apple trees to an open centre, while the gospel in North America is that they should be central leader. (High-density supported plantings are a completely different beast, with techniques specific to them.) Just reasoning from the concept that we want maximal light exposure to all parts of the tree, plus keeping the bearing area within reach of the ground, it seems to me that a "flattened" saucer shape should be preferrable to something in which growth above inevitably shades the parts below, while growing progressively farther out of reach. What is wrong with this reasoning?

I am coming at this from the perspective of someone who has managed to do pretty much everything wrong in the early years of establishing my orchard. While I was aiming at establishing a modified central leader shape, many of my older trees have taken matters into their own hands and bent their leaders over to gentle arcs headed back down towards the ground, ending up as very lop-sided open centres.

Just in passing, I have a hazy recollection from 50 years ago of an account of apple culture in some very far northern country in which the trees are trained to a continuous low carpet a couple of feet high, wherein they are protected from winter damage by the snow cover. But this may be a figment of a dotty old man's imagination...

Broomholm Orchard
Zone 5b in Nova Scotia
Re: Central leader vs. open centre
April 27, 2015 12:08AM
Great point David. I too have ended up with rather exotic shaping of my trees and find that a somewhat open center is a very appropriate way to have a lot of production without losing sunlight on the various limbs. Plus it's very fun to climb on these jumbo jungle gyms during pruning time--great acrobatic exercise.
Re: Central leader vs. open centre
April 27, 2015 03:49PM
Having an open center without question allows for maximum light penetration and highest fruiting within this scaffold area. The issue as I see it is that this space becomes your cropping limit. A true central leader tree, particularly on the more vigorous stock, allows many scaffolds, and thus a considerable higher cropping potential. Certainly there is greater shading within each scaffold than you would find compared with open center, but you get more of them. Many growers in Europe and in North America traditionally went for these forms for ease of management (like spray coverage efficiency). But for highest yield, per tree, a larger central leader with multiple scaffolds wins out, especially for cider production.

The other issue is tree strength. A branch obtains some strength from the overlapping sheets of cells when both trunk and branch lay down their secondary growth each year. When trunk is absent above a branch, as in open center management, the branch stability is compromised. This doesn't necessarily spell disaster, but it certainly increases the possibility. Cropload, snow, etc, can tear these branches like a peeling banana in my experience. So, if folks are experimenting with this method, a subdued central leader without additional scaffold branches should be allowed to grow to strengthen the sidebranches below.

The bent leader is usually the result of leader cropping. Most suggestions are for the leader to be stripped of fruit to disallow this. It does, however, subdue the vigor, keeping the tree lower without cutting that leader. If allowed to grow too large, it of course shades the tree, but we are not supposed to allow this to happen.

A point I like to offer to folks these days is that the tree is a pretty nice vehicle to effectively increase food and organic matter production in the landscape. It beats all other forms of vegetation simply due to its aerial space occupation. By letting a productions system like the tree explore a maximum area, we increase production. This includes the crop of course, but it also mines nutrients from air and soil and deposits them as litter and prunings, thus increasing topsoil, mulch, and btu's for the farm. A plant, be it an herbaceous species, or tree, is quite limited in these possibilities when it is forced to maintain a particular height.

So, with proper management, there are probably hundreds of systems, the open center included (look at what the Japanese were doing in the 1800s with their high density opencenter production if you want to see something really cool), that can be done in a satisfactory way. If an orchardist is willing to take the extra time to monitor for potential breakage, because they want ease of spraying and harvesting it makes sense in the same way farmers engage in the upfront costs and management particulars of high density trellis growing. But, for maximum production of organic matter, carbon sequestration, wildlife habitat, minimum ammendment input, and yield per tree in the ground, the larger sized central leader tree is the best option.

Walden Heights Nursery & Orchard
Zone 3 in Vermont
Re: Central leader vs. open centre
October 14, 2018 09:18PM
I am struggling to define my pruning style and can see the merits in both of the above..Some of my trees want to be a modified central leader, some seem to want to be delayed open center and others again just confound me with recurrent water shoot growth.

I have about 1500 tress in the ground, half them, 2 years settled, the second half only 1 year in the ground. They are all cider varieties, over 50 in total, all MM106 root stock.

The more mature tress I gave a heavy prune last winter, which got me ton of water shoots, that I thinned a little in the summer. I also had next to no fruit which is not an issue this year but it was less than the previous year and I did have a buyer lined up that I had to disappoint.

I think I will try more branch spreading this winter and less pruning.

We did have one tree that had a magnificent abundance of fruit, the rest though 90% empty, even though they are all treated the same, it's hard to fathom.

I did not pay close attention to the 30% pruning rule in my determined push to get the structure I wanted established early on and it bit me hard in the rear.

Its a modern planting style at 200 trees per acre on staggered rows.

The trees will see a lighter touch this winter to hopefully guide them towards long term shape and some fruit next fall.

My first post on the forum though I have read it for a couple of years, so thank you all for the resource.

Ger Bartle
Kinsale
Ireland
Re: Central leader vs. open centre
January 27, 2022 02:14AM
I appreciate the notes in this ol' thread. I have about 30 seedlings that will be in their 4th leaf this season. This is my first time around pruning a seedling from the early stages and I'm feeling the pressure to make so decisions that will effect things for a long time to come.

The principal question being, central leader vs open center/multiple leaders. I'm imagining some very large trees down the line, but they are in areas where I will driving past with a tractor regularly so I cant do too much spreading down low.

Center Valley Orchards
Washington State - Olympic Peninsula
Re: Central leader vs. open centre
March 27, 2022 08:37AM
Thanks for bumping this up again, Shay. We’re also in our fourth year here with mostly standard roots. Still no apples and I’ve been waffling on this dilemma as well. I started out feeling convinced from Michael’s books that a modified open center was the way to go for these guys- let them get up off of the ground, then spread them out so they get lots of sun. But while some trees seem to like this treatment, others keep sending that central leader right up, so I’ve started trying to listen to them and let each variety do what it wants. Anyone else see the potential mess down the road yet?

The waffling continues as I weigh in Todd’s point about production, and think about the benefits of getting those apples up off the scab laden orchard floor. Also, while it may be fun to climb in those jungle gym trees, I’m helping the neighbor prune his 15-20’ tall open center orchard right now, and I’m continually frustrated at how many ladder sets it takes to circle one of those gangly monsters. Also, asking all those trees to spread their arms for the past 25 years has them all growing into each other so badly he’s contemplating cutting down every other one. They’re spaced a little on the tight side, (20’x20’) but I’m sure he wouldn’t be having this bad of a problem if he’d just let them grow straight up. Admittedly, the last time I picked in an orchard of old school standard central leader types was almost 20 years ago, but I remember it being way easier to get around those guys than this. I certainly never cared then that no light got to the apples in the center of the tree, because then I would have had to go in there to get them!

Anyways, most of our trees are just above ten feet tall right now, and have the basic structure to begin the modified open center approach. I’ve decided to do almost no pruning this year while I think about it and see what the trees do, but I’m leaning towards letting the central leader voice take the lead. I realize that this might be my last best chance to waffle on this, so I’m happy to listen to any other voices out there as well, especially from anyone who actually has a central leader/large tree orchard (Todd?) and can give me some of their perspective- the ups and the downs, as it were.
Re: Central leader vs. open centre
March 27, 2022 04:21PM
We should get a clarification from Shay about the "seedling" term. I will assume this in the horticultural sense that it was generated from seed. This brings up a salient point in pruning- that it can set back production and that it can produce rebound wood. Gerard above asked back in 2018 about pruning his brand new trees. My suggestion is to keep your fingers away from the trees until they are bearing unless you can make a good case otherwise. In the case of a seedling, as we may do if we are trying to come up with new varieties, any pruning will add a lot of years to that first crop date. Pruning can of course dial in a fine shape with early cuts, but there is a price to pay.

Prairie, your frustration is one I, Michael (whose trees were generally about the size of mine- in that 10-15 foot range) and other big tree growers have shared. I think any prospective grower needs to have a moment of reflection before they plant that first tree. The tree size is comingled with the entire layout and management style. When I set up an orchard for a client it is a lot more like a business manager/psychologist than a horticulturist. For example a younger family who is patient and is doing a lot of processing, a lot more standards wind up in the landscape- maybe with a few bud 9's for an early bite. Someone going the commercial route gets the advice to include more precocious stock for part of that layout. The pruning style and tree form will forever be linked to the variety of stocks and each's limitations. Reducing the overall size of a standard, through modified leaders, etc. is certainly possible. There is no question however that attempting to violate a full vigor stock to picking height is (almost) a fool's errand. What needs to be decided (and this is more for those who are ABOUT to be planting) is how quick do you really want fruit, how long do you want the tree to live, are you willing to spend time in the tree pruning and harvesting, and how much babysitting do you want to do. Also, most of the problems in our orchards are from incorrect tree spacing- pruning in my opinion should not be a method for keeping trees in bounds- that should have been addressed on planting day. Another consideration is cultivar choice, at planting time or as a topwork. A summer pearmain is going to have a fraction of the vigor that a howgate wonder will. My farm is set up to split the crop- easily picked fruit for fresh sales, the balance for processing (mostly hard cider mix). I love the big trees, and this works fine for me management wise. I also grafted plenty of those trees 25 years ago, so that is easy for me to say. I will add (for Prairie) try to climb more when working in the tree, using the ladder as little as possible. It is quicker and WAY safer. I pruned hundreds of trees this season and have not used a latter yet. As mentioned in other threads, I like to maintain the tree to be a sort of ladder, and prune it to accommodate this. To return to the thread point, gutting a sassy tree in order to turn it into something else is going to be a rough ride. Those open centers and highly modified forms always lend at least to a semi-dwarf (m7 or smaller). And of course commercially that sort of modification has drifted to antiquity, in favor of $30,000/acre high density trellis systems like central axe, etc. So, expect the big girls to be bold, large and slow to bear. You will be able to sculpt and modify, but only to a point. Also expect them to give 10 bushels or more and live 150 years, evade drought and devoid of trellis systems. Its a personality thing in the end, the way you want to make fruit.



Edited 1 time(s). Last edit at 03/27/2022 04:30PM by Todd Parlo.
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