Chill-sensitive fruit truits and chlorosis

Amanda says...
Sorry - pics did not get re-posted when I corrected some info and resubmitted..
Here are the pics again
Shady side versus sunny side..

Pictures - Click to enlarge
Picture: 1	Picture: 2

jakfruit etiquette says...
Hi, have you considered that the plants inactivity protects it somewhat from cold and frost injury. Frost can be much worse in spring if it hits active new growth of the spring flush.

Amanda says...
Yea Jackfruit etiquette - this can be true in that the plants will dismantle the chlorophyll molecules in order to protect themselves, basically.
I believe this is happening somewhat - as a piece of tape put across a leaf and then peeled off several weeks later - will show *green* under the tape - but chlorotic where exposed to the sun.
Really interesting I think! And hence why they are green on the shady south side - and chlorotic on the sunny north side (as the winter sun is low in the northern sky then, here in our lower latitudes, of course)

I just want to gather the "e;intelligence"e; on these more rare plants - so that we can build on our knowledge about growing them in cooler climates.

Yes that is also possible David01 - but then that would apply for all of our evergreen trees.
That wouldn't explain, for eg: why the Kohola Longan seedling tree becomes chlorotic in winter - but the Chompoo marcot tree does not - even though they are planted 3m apart, treated the same etc.
I suspect that the Kohola is chill sensitive, therefore..this might mean that folks in cooler climates are better off planting Chompoo, for eg.

This is not a soil issue per se/strictly. Sure there are different things going on in winter, compared to summer - but it's not the problem as such.

That part - what is happening in the soil - is very complex and might be a much for this forum perhaps (don't want to scare folks off..I just want to collect the data/info)
For eg: our coastal sands are highly aerobic and thus oxidative soils.
They are also warmer than say yours...for eg. This also affects their redox potential and redox and pH are linked. So I understand all that part. I have been researching this for several years now..and have come to realise that we still have so much to learn! Even the difference between my irrigation season (with the limey bore water) compared to the "e;clean"e; rain water in winter - changes my soil chemsitry...sigh!
You might find these links interesting though - the lychee one a difference scenario - but along similar lines.

http://www.tropentag.de/2007/abstracts/full/311.pdf

http://www.publish.csiro.au/cp/AR99076

Amanda says...
This our marcotted Chompoo longan compared to our seedling Kohala for another eg? ...they are only 3m apart - the Kohala is 10yrs old and 5m tall - and it starts going chlorotic at this time of the year, every year.
The Chompoo is only 3yrs in and about 1.5m tall - it doesn't go chlorotic over winter.
We are having quite cold nights now (althoughby cold nights I mean from about 3am onwards...) and clear, dry and sunny days.

Pictures - Click to enlarge
Picture: 1	Picture: 2

Amanda says...
Yea that's kind of along the lines of what I am banging on about David01- but I am interested in woody plants here...(fruiting ones of course! :) ) as well - they have the ability to cold acclimate.
Anyway too much science-y stuff scares regular people off a topic, I have often found :/
I am still really interested in anyone else's experiences of the "e;winter yellows"e; in sub tropical fruit trees, out there?

Amanda says...
If only it were that simple David01 - I would be able to spray some zinc-chelate around and be done with it. But certainly, zinc deficient leaves are more photosensitive - but other research has turned has turned up Magnesium and/or Boron deficiency.
Then you have factor in each species...and even in between the different varieties and races (like with mangoes)
There is no one universal answer. To know this topic inside and out you need be a Professor of Plant Physiology - honestly! I won't pretend to have all the answers that's for cetain - but we can often find solutions to problems that we don't yet understand - and that is what I am looking for here.

It's actually a really interesting topic though, for people who just love learning about plants. We are quite lucky to have just one of those Professors nearby, over here...who has taught us alot about delayed greening in our native plants - and anthocyanin production (eg: new leaves that are red) as photoprotective mechanisms.
And those adaptations are also seen in tropical/sub tropical species - because the light intensity is so strong, of course, near the equator.
It's also very strong over here in WA too though - because it's much drier and therefore clearer ( = heaps less cloud cover)
But the plants don't get the chilling overnight like they do outside of their native zones 'up there'...so they are mostly not adapted to the situation (eg: google 'stomatal conductance and chilling sensitivity)

There are also some definite genetic reason why some tropcial species will never tolerate my climate in the next few generations for eg...it will a very, very long time before purple mangosteen will ever be grown in Perth, outside and in the ground.


In the meantime - I am trying to focus on other people's experiences of this problem, and if they have tried anything to alleviate it.

For eg: there are some foliar sprays that can be applied to assist with drought protection and/or frost resitance - perhaps others have tried foliar sprays of plant "e;e;sunblock"e;e; to get their plants through the cold-acclimation/hardening off process...
Maybe others feed their trees certain nutrients when that cold night/sunny day time period exists.
Others might have tried light shade cloth...
etc....

That kind of 'stuff' ...

Amanda says...
I found the whole paper David01...it's very interesting thanks...it even has this picture in it...which is what I have observed also.
Also interesting about the accumulation of iron in the leaves when they are zinc deficient too.

And Zinc Efficiency and Inefficiency are genetically based....I wonder if the Kohala longan is an *in*efficient type and the Chompoo is an efficient type. Hmnnn!
Maybe that is getting ahead of things though...

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1469-8137.2000.00630.x

Pictures - Click to enlarge
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David01 says...
Hi Amanda,
If high bicarbonate inhibit Zn uptake then in that case Chlorosis should happen at any time (permanent), but not waiting until temp drops below 10C for tropical/subtropical plants (temporary). My opinion for Chlorosis is as below:
1. If Chlorosis occurs during ideal climate then the plant may have issue with incorrect fertilizer, incorrect PH level, lack of trace elements, poor soils or water etc . Then Chlorosis issue can be corrected accordingly by followed recommendation from experts. However, in practice it is not easy to find the cause or correct solution unless obtained leaf test results or after many trials
2. If Chlorosis occurs due to temp drops below limit during winter, plant tissue could be damaged and solution 1 will not fix problem immediately as plant needs to wait until next growth season to repair the damage tissues by itself and solution 1 may be applied to speed up tissue repair but not before then. And of course unhealthy plants (due to 1) will be more vulrenable to cold weather. Cheers.

Amanda says...
Yea David01 - that is a good point - and oddly enough I was just thinking about how they are fine in the warmer weather and how can't I even tell that the leaves might be on the low Zn side anyway (without an expensive leaf analysis) when they are not showing any deficiency at all....so annoying -because I also agree with JFEtiquette - there can be so many knock-on effects from adding the wrong things and/or at the wrong time...been there, done that too...
It's a bit of a rabbit hole isn't it? I can get my head around a bit of the individual chem ok but once the temperature and water changes kick in as well, then it starts to do my head in.
Have to be careful not to 'over think' it also.
I am going to go with adding a little zinc sulphate in Autumn though - just to see what happens....if anything.

David01 says...
Hi Amanda,

Are you Amanda19 10years ago? Welcome back.

Many studies tried to work out solutions to improve plants with zinc deficiency and plants growth in soils with low level of zinc, and some of them are adding Zinc, cut back high phosphorus fertilizer and secretion of root exudates, as various types of root cells sense microbes or compounds in the soil etc. However, I think these findings only work in the ideal climate. As I already tried to spray Zinc and iron Chelates on leaves and improved microbes in soils on Pumelo and other tropical fruit trees in winter when all young leaves get chlorosis but result was not better. However, when the weather improved, all the leaves back to normal in Dec instead of Sept. The reason took that long as plants need time to wake up and time to repair damaged tissues. By dig in too much in research documents sometimes make us confused and can lead to mistakes as jakfruit etiquette comments. For example, for chlorosis issue, one document says lack of Iron, others say Zinc, then PH, then soil, microbes, water etc. etc. you can find more than hundred suggest solutions for one simple chlorosis but only few solutions can be applied to correct the problem if and only if diagnosis is correct and this is the most important but tricky part and most of us fail to do so as lack of resources or experiences. Cheers

Amanda says...
David01 - do you get the chill-chlorosis on plants in your greenhouse as well?
Is your greenhouse heated?

I have had problems getting my fertilising regime sorted out here - as it wasn't until I got the bore water tested that I realised where the problem was.
Now I think I have it under control - so it's interested to see that - so far - the peanut butter fruit trees are not going chlorotic....even though we have had very cold nights and bright warm sunny days - and really dry weather...perfect conditions for that sunny-side chlorosis to happen.

(the bananas are starting to go though)

Anyway - I will see what they look like at the end of winter....but I was thinking that maybe they do better/stay greener when then they head into winter with a full 'larder' of zinc (and/or Mn, Fe) - especially given that Zn mobility in the plant is also linked to it's levels (ie when it's low then it doesn't get translocated to the new growth...)

But it could also be because the plants are much bigger and thus have a more established root system - or that I have been acidifying the soil over summer - and this has made the zinc more available at the criticla times of growth?

I can't say that I have ever had much luck with chelate sprays either to be honest - so it's interesting you have mentioned that also.

Amanda says...
Makes sense David01. And there are the sub tropicals that can be deciduous or semi deciduous in our cooler climates, like the Annonas. Our Tropic sun atemoya is buck naked by late winter and the montanas partially. The Malabar chestnut is also partially deciduous.
The leaves on these do go yellow before they drop - so perhaps leaf senescence, but due to stress (cold-induced stress) rather than ageing - and is part of the problem.
Amazingly the Jackfruit is not bothered in this way, in winter...but does get a little bit of tip die-back when it's very wet and cold.
There are so many differences between them all, aren't there.

Your experience and results with the heating is very helpful thanks.
You sure do have the fruit tree collecting bug don't you!? haha....it's very addictive.
One of the next stages, here, is to see what trees will be able to ripen any fruit in this climate.
Eg: the Tropic Sun atemoya is carrying young fruit now - it remains to be seen if they will ripen, now it's winter - or hang on until warmer weather?
I can grow Jackfruit, also - but will I ever get a ripe fruit, if any at all.
That's all part of the fun and the challenge though isn't it! :-)