Interior foliage on shimpaku turning yellow

GenBurnside

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I've had this shohin shimpaku for about 6 months now, and I noticed the interior foliage starting to turn yellow. I haven't really done any defoliation to it, so could this be caused by low sunlight?

Any help or ideas would be appreciated!

shimpaku.jpg
 

Adair M

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You said that you "really haven't done any defoliation to it".

So, what HAVE you done?

Have you been keeping it pinched back?
 

sorce

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Yeah....
He knows it ain't been pinched.

Almitey then.

Sorce
 

GenBurnside

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Nope, I haven't been pinching. I read this a couple months back, which led me to mostly leave it alone for now: https://crataegus.com/2012/08/26/how-to-pinch-junipers/

I did trim half a dozen shoots with no branching or budding about 2 weeks ago, but that's all.

Is there a good rule of thumb on how much to pinch/trim back and how often?
 

Adair M

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Nope, I haven't been pinching. I read this a couple months back, which led me to just leave it alone for now: https://crataegus.com/2012/08/26/how-to-pinch-junipers/

Is there a good rule of thumb on how much to pinch/trim back and how often?
Good.

When I view the picture on my iPhone, and I enlarge the picture, I can see that some of the yellowing foliage was pinched. It may have been pinched prior to your ownership.
 

sorce

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Not Brown tips?

Yeller foliage?

Sorce
 

GrimLore

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Is there a good rule of thumb on how much to pinch/trim back and how often?
For now trim with shears all the brown foliage right down to the branch, keep it in the sun, water but don't let it stay real wet(easy in full sun)... While you are in there check for mites or other critters...

Grimmy
 

Adair M

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Not Brown tips?

Yeller foliage?

Sorce
Yes.

Let's work this out.... Pinch off the tip, that little piece of juniper "leaf" stops growing. The tip turns brown. The rest of the "Leaf" or needle, stays green for a while. For a while. Then what happens is other parts of the tree grows. Where there are growing tips, those tips produce the hormone auxin. Remember, auxin the the signal that tells the roots to grow because there's active tip growth.

Well, guess what? The pinched tips aren't growing. Therefore, no auxin. There's no hormone signal to tell the tree there's any reason to send sugars there, because there are other places on the tree that are signaling there's active growth, so the tree sends its energy to the actively growing areas, as signaled by the glow of auxin.

So, what happens to the pinched foliage? It doesn't get fed. It yellows, and dies.

I just took a look at my junipers. Not a single bit of yellow anywhere. I don't pinch.

I see you're in Decatur. Are you an Atlanta Bonsai Society Member?

And yes, Dav4 is correct, too. Excess soil moisture can also cause yellowing. Don't do anything now, but next early spring, you should do a "half bare root repot" to transition it to good bonsai soil. I teach classes at Plant City Bonsai. Call Steve to get on his email list.
 

sorce

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Thanks for that quality explanation to a half cocked almost drunk question.

The last 2 days....I drove behind 2 different teslas on the way to work.

Random!

Sorce
 

GrimLore

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Old interior foliage does this around this time of year. Probably nothing to worry about from what I see.
For now trim with shears all the brown foliage right down to the branch, keep it in the sun, water but don't let it stay real wet(easy in full sun)... While you are in there check for mites or other critters...

Grimmy
Enough said or does this really need to be complicated :rolleyes:

Grimmy
 

GenBurnside

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Adair, I actually met you (very briefly) at Plant City Bonsai last spring. I was in Dave's beginner class while you were teaching a JBP repotting one. I'm not a member of the ABS, but am thinking about joining this year.

I swear I used shears to trim back a few shoots last month, but it's possible that I used my fingers. Having a 6-week old little girl has really done a number on my memory!

I'll do a better job at checking the soil moisture too... I killed my JBP last July from UNDER watering, so I might be drowning this little guy.
 

watchndsky

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I dont understand what the difference between cutting and pinching can someone explajn. Both remove the shoot? How does uskng a scissor or shear not produce the same auxins
 

Adair M

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I dont understand what the difference between cutting and pinching can someone explajn. Both remove the shoot? How does uskng a scissor or shear not produce the same auxins
It's not the tool. Improper "pinching" or "cutting" yields the same bad result.

The term "pinching" means removing the growing tip of juniper foliage. Never, ever, just remove the tip. The part left between the new truncated end and where it is attached to the branch will never grow again. It will stay green for a while, but it will eventually die off.

If you need to shorten juniper foliage, remove whatever needs to be removed at the point where it branches off from its supporting branch. Don't leave stubs.

I'm not discussing jins in this description. Just talking about the green foliage part.

It doesn't matter if you use fingers, scissors, or light Sabres, remove it at the joint.

Now, someone will say that they have seen Kimura pinching a couple of his junipers in his garden. Even say they've seen Ryan Neil pinching junipers. First off, Ryan isn't "pinching". He's using his fingers, yes, to clean out the old weak, and yellowed interior growth of the tree he's working on. But he's removing the entire twig. That's not "pinching". And Kimura? The video shows him strolling thru his benches as he's being interviewed, and as he walks along he casually sees a bit of foliage that's grown taller than the Sihlouette of the pad, and he reaches up and pinches it off with his fingers. So... "Pinching" is ok, right? Kimura does it! But what you can't see is exactly where he's detaching the foliage. He plucks the foliage off at the base. He leaves no stub. Sure, he's pulling it off with his fingers. But it's more of a "finger prune".

It's NOT the tool. It's WHERE it's cut.
 

leatherback

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I dont understand what the difference between cutting and pinching can someone explajn. Both remove the shoot? How does uskng a scissor or shear not produce the same auxins
There is a fairly long debate on this subjject in another thread. It boils down to the tool you use, the point at which you want to trim back and whether you want to remove one branch from a tuft, or aim at removing all the growing tips from the whole tuft. In any case.. Look it up on the forum, there is a long thread on it.
 
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