Pruning Chinese Pistache 'Keith Davey'

pasomike

I am a volunteer on the landscaping team for our community and very interested in how best to take care of our trees. Last fall we planted 30 Chinese Pistache 'Keith Davey’ (seedless male clones). Now, after the first growing season, we are looking for some pruning guidance on how best to train these trees.

We had no luck finding someone in our area that has experience with these trees. The only information with some detail that we could find was on the internet. It was for pruning pistache propagated from seed (see below) -- and nothing for the 'Keith Davey' variety.

-- from <http://hort.ufl.edu/trees/PISCHIA.pdf>
The tree needs special pruning and training in the early years to create branches in desirable places along the trunk. It often grows with few branches, or with branches clustered at one point on the trunk, if it was topped in the nursery. Pick one to be the trunk, another to be a branch and remove the rest. Allow the tree to grow taller and again top the unbranched trunk 18 to 24 inches above the first pruning cut to force branch development there. Build the tree in this fashion until a desirable structure with well spaced branches is achieved.

Now for our Questions!
Does the above information for pruning make sense for our trees? Since some of the trees have multiple leaders (3-5) already, how many leaders would be best to remove at this time? At what length should we prune off these leaders to force new branch growth? How do the dynamics of strong winds and the varied growth rates (see below) factor into the pruning decisions?

Background info.
Last October we planted thirty 15 gallon ‘Keith Davey’ Chinese Pistache (seedless male clones) to meet our needs for a drought resistant, shade tree with easy clean up. The trees came from the nursery topped at 7 feet. The trees had from 2 to 5 leading branches. These leaders were 1-2 feet long and clustered at the point (or very near it) where each tree was topped. None of the leaders were pruned off at planting time.

The trees are planted 4-6 ft. from the edge of a wide (10-12 ft.) pedestrian sidewalk with one and two-story condos on the other side. Because our location is very windy in the spring and early summer, the trees were double staked with the nursery’s trunk stake left tied to the trunk so the winds would not snap the trunk (we plan on removing the nursery stakes this winter). With the strong winds some of the leading branches were torn off…major bummer.

Varied Growth Rates after first year (see photos at bottom):
- Some rapid growing trees have leading branches 5-7 ft. tall with no other branching on them or the trunk.

- The medium growth trees have leading brances 3-4 ft. tall. Some trees have no other branches than the leaders. Other trees have small branches growing from the leaders.

- Slow growth trees with leading branches that only grew 6 inches or so, with no other branching or just a few small ones.


We appreciate any help you all can share and look forward to hearing from you soon!

- Mike



Rapid 3 leads


Medium 4 leads


Slow 4 leads with branches

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Eric Frei

It appears all had to have their main stems cut to encourage branching.

Very long leggy growth indeed.

It makes me wonder what on earth happens to these trees if they're not pruned? Certainly from pictures I found in Google they seem a domed canopy full tree and not spindly.

On all of them I would select one of the stems as the "main trunk" and then head back the others for more branching.

The leader that becomes the "main trunk" I'd go with that advice and head it back again maybe 2' above the previous cut.

The other leads I'd head back maybe to within 1' of the trunk.

Doing this whilst the trees are very young means most of the tissue cut is pretty much 100% cambium and if ever there was a time to do it ... it is now. You also mentioned wind and branches breaking so shorter stronger branches are preferred.

Also, make sure you are not adding to this spindly growth with lots of N fert!

I have red lined my ideas for the 3 scenarios.

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treeseer

I (hesitatingly) agree more with Ekka than Gilman, more subordination and less removal. Leaving only 1 lateral branch per node is a very slow way to build a crown, and the main thing is , it would not be as balanced. A lot of Gilman's pruning advice seems oriented to street trees so it is a bit harder than landscape trees need to be pruned.

It's an unusual species indeed if it sends up a 7'+ whip with no laterals. Are there pruning scars lower on the trunk?

Eric what would you do with the laterals that you reduce to 1' (I would leave more) when they flush out? Leave 1 or 2 and reduce to maintain subordination?

Important imo to make all cuts to full buds, nothing internodal. And most important of all to have planted the roots properly, or it matters not what you do with the branches. Can you please post a of the trunk flare, where the first root is?

Eric Frei

When they "sprout" I'd have maximum two (that grow upwards and outwards from the trunk) ... then if they grow spindly another 18" perhaps and cut again, when that sprouts maybe leave 3 shoots.

Yeah, maybe more like 18" out, just not sure how thick these branches and trunks are expected to get in that location. Idea is develop a branch structure. Then the second cut another 18" away .. and that should do it.

I've made an impression of the first pic so we get bit of an idea in our heads as to development.

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treeseer

ok I can follow that. re the central leader I would look for laterals forming before heading--best not to retard the tree more than is needed.

re heading, best done not only to a bud but a bud that is pointed in the preferred direction.

Jeff Darby

Hence the term formative prunning, I would also lossen off the strangle hold on the main stem, it's to restrictive, they have to have some movment to build good root formation otherwise when you do remove the stakes the first minor blow you have their going to fall over.

I would cut the tape and replace with a flexable tie point in three locations from the top of the stem, middle and the bottom,tight enought to support but loose enought for these young sapplings to get used to a little wind.

I can also see your mulch is touching the main stem,this is not good remove your mulch back to give about 100mm radius of clearance from the stem to the mulch.

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pasomike

Wow, thanks so much for the sage advice!!!

Okay now, let me see if I've got it right for the pruning...

First pruning:
Do not completely remove any of the leaders. Cut one of the leaders to about 2 ft above the topped trunk and make it the "main trunk". With the other leaders cut them off lower at around 18" above the topped trunk, making them "subordinate" leaders.

Second pruning:
When "subordinate" leaders grow out remove as needed, leaving a maximum of two along with the "main trunk". If "subordinate" leaders grow spindly, cut again at around 18". Do not prune the "main trunk".

Now for a few other Questions...

1. Would there be any other time that I might prune the "main trunk"...say if it grows real tall without branching?

2. Right now there are several trees with only 2 leaders. Do I make one the "main trunk" cutting at 2 ft. and make the other the "subordinate" at 18"?

3. I've got one tree with 5 leaders, all about 3-3.5 ft. tall (see photo). Should I remove at least one of them during the first pruning?

Thanks again for your help!

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pasomike

Here are two photos of the trunk flare of the trees. The first one is of the tree with three 7 ft. leaders. The second is the tree with the five leaders 3-3.5 feet tall. Both trees had great trunk caliper growth to about 1.25 inches.

- Mike

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treeseer

first pic shows a lot of roots and no stem girdling--good.

second pic there is still dirt on the flare.

Strongly recommend you retain a local expert to oversee your energetic management of these trees. Se if you can find one who follows what's said here. If there's an alternative approach let's hear it.

Eric Frei

My responses are in blue.

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pasomike

hmmmm...you mentioned "stem girdling" which doesn't sound good to me.

So, I went out and cleared the mulch back away from all the tree flares and took some photos. Seven of them looked much different than the rest.

I'm going to start a new post titled "Stem Girdling by Roots...or not?" and attach the photos.

-- Mike

Jeffrey Lovstrom

Here is the problem, those trees are nursery trees and all the laterals were cut off and the tree is tied to a stake!!!!!! Here in southern California, there are many pistache and as a certified arborist, I would not of accepted those trees. At least take those ties off and leave the outer stakes and dont prune nothing. By the way, check if Urban Tree Care works in your area, I think they do.
Jeff Lovstrom

Eric Frei

Jeff,

have you got some pics of what they're supposed to grow like without all this intervention?

These seem so weird, whip sticks. A comparison would help that's all.

If these particular ones weren't cut, ever, what do you think would happen?

From the pictures seems they just grow 10' long sticks?

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Jeffrey Lovstrom

You can go to Google Images and see alot of them. They are really nice trees. The trees from the nursery are not good specimens. They remove all the lower branches and tape them tight to a stake.
Jeff

Kathy Hobbs

I just planted one of these trees today and thought it looked really "leggy."
I wnet out and pruned it just like it says to do on here so now---we'll see what happens.
Any other trees I've planted just sort of sit there building a root system I guess for about 3 years before they finally take off. We'll see what this one does. :-)
Some people say their trees start growing on the top the first year they plant them but I've never had one that did.
Even the Royal Empress tree I planted took about 2 years to take off.
I think people might tend to exaggerate when they brag about their trees growing a foot or two the first year.

Kathy

bjdevil99

This thread was really helpful, and led me to pruning one of my three C. Pistaches well. However, I have two trees with questions - both related to leader development and general shape.

Tree #1 - This one has a several branches going skyward. I plan on trimming them back a bit, but I can't pick the right leader. There is a stem that is continuing straight up, but there are 2 branches growing (to the left in the picture) growing much more quickly. Do I a) cut the two more dominant branches way back and hope the smaller leader grows faster, or b) pick one of the two dominant growers and cut off the other branches?

Tree #2 - The real problem tree. I cut off the two lower branches already (where the white marks are in the picture), but the real problem is up at the top: There is no leader. Instead there are 5+ branches, with all of them growing off in various directions and at least 30 degrees off of the Z-axis (i.e. straight up and down), like a giant crown of branches. (In the picture there is an optical illusion - the smaller one that looks like it's straight up and down is actually growing away from the camera).

The red marks in the tree were suggestions from a friend, but that still doesn't leave a good leader. (Maybe the one that's not marked red to be cut?)

What do I do with this tree? Make the cuts at the red spots and live with a tree with no leader? Cut off all except two and live with a forked tree? Cut off the top of the tree and start over to get a proper leader (the green mark), setting the tree back a year or two?

Thanks! Bryan

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Eric Frei

Some more info from University of Florida

ENH641/ST482: Pistacia chinensis: Chinese Pistache

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mc510

Hi everyone. Last year I planted 3 Chinese Pistache along the sidewalk and now that winter's here I'm thinking I should maybe start to prune them a bit for training purposes. I saw the great advice that folks here gave pasomike; my question is a little different though.

All three trees appear to have their central leader cut in the nursery, and they've developed a big cluster of side branches along the top 6" or so of the trunk. In order to get attractive upright growth, I gather that I need to promote evenly spaced scaffold branches, which is definitely not what I have now. So what do I do at this point? Should I remove some/most of the "surplus" scaffold branches? Should I select a new leader, head everything else back to be shorter than the leader, and then plan to remove the "surplus" scaffold branches some years later?

I'll attach two views of one of the trees; the other two are pretty similar.

Thanks in advance, and Happy New Year to everyone.

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Eric Frei

This is a tough one, sort of between a rock and a hard place.

Neither of those branches are ideal to form a central leader.

Lets see what others say, I'm inclined to say do nothing yet.

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Gandy_fam

Hello - I have a two-year old chinese pistachio, which I think needs pruning this winter. I attached some shots. I think I need to take off the lower branches, even up the top main branches and tidy up a bit -but how much is the question? Gratyeful for any any advice - we're in Melbourne Australia.

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Eric Frei

Yeah, I'd take the two bottom ones off as well.

As for the rest I cannot say, pics could be a bit larger, aim for 900px wide and under 300kb file size.

I think you need to subordinate the smaller/shorter of the two main leaders which both arise from the trunk, let one assume apical dominance.

These trees sure need some care, grow spindly like.

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Gandy_fam

Thanks Eric - reposting pics a little larger. Understand I need to create a dominant leader - so take the second trunk off further that the main one - yes? Should I clean up all the little side growth at this point?





Marian