Charles, If you stimulate a big top growth, that will send a massive dose of auxin downward, telling the roots to hurry up and catch up. So I'd not worry about creating an unbalanced situation for more than a very short period of time.

Dr. Manners,
I’m trying to clarify some things to myself. Until last year I treat citrus like deciduous fruit trees and I realize that I’m doing a big mistake, thanks to this great forum with great people.
When the new flush start this is because the cytokinin level is higher in the plant then the auxin level.
When the new flush stops to grow this is because the cytokinin and auxin arrive to the same level, auxin because was produced by the new flushing.
During time when the leaves become ‘mature’ the auxin level is higher then cytokinin because of new leaves and twigs which are producing auxin.
In the mean time as far as I understand the auxin is responsible of root grow also, so the higher auxin level will simulating the new root grow.

So, that’s mean when the new flush will stops to grow, then the root grow will start?

Please, correct me if I’m wrong and apologize if are stupid questions.


Anybody is welcome to answer!

Karoly, In general, yes, what you're saying is true -- root flushes tend to alternate with top flushes. Where I'd tend to disagree is the concept that a top flush stops as the auxin and cytokinin levels equal out -- that's not necessarily the case. Once a flush begins, the tip of each branch is a new apex, exerting its apical dominance on all buds below it, but it is not being inhibited by anything. Rather, it has a certain number of new leaves/nodes preprogrammed to be produced (in citrus, usually 4-10), at the end of which it stops. But I don't believe that stopping is an auxin nor a cytokinin effect. As the new buds mature and harden up, they produce the primordia for the next flush, so the number of leaves/nodes is predetermined.

Citrus is unusual, compared to most other trees, in that it fails to make a terminal bud; the new twig just ends with nothing. So the next flush comes entirely from axillary buds.

Dr. Manners,
Thank you very much for explanation.

I have just transplanted an orange tree from one pot to another pot(upsize).I noticed in the last two weeks that it was putting out new buds...Its towards the end of winter here in NZ.....My gut feeling was that it was bad to transplant when it was putting out new buds...as i am aware citrus tend to go top growth/roots/top growth/roots.....I am fairly sure i did this before and the top growth stopped dead in its tracks....maybe to put out roots as it sensed a disturbance in its root system....I have loosened the outside roots and put into fresh potting mix.....Is it a bad idea to transplant when top growth is going on or better to transplant when no top growth going on...so you know its in root growth phase? your thoughts experts?

I've transplanted successfully when the tree was putting on new growth. I don't think it is as important when one transplants, as it is how carefully one carries out the transplanting process. Over the years, I probably have transplanted a citrus tree, during every month of the year, and in most every cycle of growth (even while in bloom). Again, it is nice having you back on this forum. We missed you when you were away y. Take care. - Millet (536-)

as to "forcing" a tree to flush new growth when it should be putting on new growth.. Just curious if bending the branches lightly( like when trying to get a T-bud to grow) would work in a pinch??
I have done this a few times to get a branch to catch up to other branches but never because the entire tree was not flushing new growth and never any fruit on the tree at the time..
It can be a very delicate process as I broke quite a few branches before I figured out how far to bend is too far..
Just curious...
Gina *BabyBlue*

Gina, I also noticed that bending branches down led to a new flush of growth on those branches. I have a small potted Dunstan citrumelo that had finished a nice flush of growth. I decided to clip some weight near the ends of two of it's branches to pull them down a bit to get them spaced out better. Those two, and only those two, branches then put on another strong flush of growth. Anyone know what bending is doing signal wise to the plant?

Sorry, I have troubles to get what remaining/empty calyxes are ...

Can you explain please ?

http://www3.hcs.ohio-state.edu/wiki/index.php/Calyx

aha, so what holds the fruit ...