Yellowing leaves on citrus

Letsgokate

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I've done a search on the forum and couldn't find a post relating to this. I have yellow leaves on some of my citrus, started with the lemon, now on the mandarin also has some yellowing of the leaves. I did a search and had come up with that it was a magnesium deficiency, the soil here must be low. Anyway I have put epsom salts 250g mixed in a bucket of water several times on the lemon, no change and then in winter I used a citrus fertilizer with trace elements on all the citrus. At that time it was only the lemon that had yellow leaves. Start of spring I fertilized them all with Dynamic lifter, so alternating between the citrus fertilizer and dynamic lifter.

I was going to do the epsom salts again, but wanted to know if there was anything else I should do? I had read to apply a hand full of Magnesium Sulphate [Epsom Salts] per square metre under the tree out beyond the drip line. Does this mean no mixed with water?

And then the same thing with some Dolomite. and to pull the mulch back which I had done for the fertilizers.

I haven't used dolomite on them.

Appreciate any advice :)

I'll post some pics soon.

Meyer Lemon, first pic is of the worst of the leaves on the bottom of the tree

Myer Lemon.jpg


New leaves starting to yellow

Myer Lemon 01.jpg


Mandarin, not as bad.

Japenese Mandarin.jpg


Japenese Mandarin 01.jpg
 
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Mark

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Great images Kate!

It looks like an iron deficiency actually that's the first thing that comes to mind because it's one of the most common citrus problems and the yellowing with stand out veins is a give away.

Iron chelates should fix it and the product/mineral is easy to find at any gardening centre.
 
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Letsgokate

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Thanks Mark, knew this was the place to ask :). Iron deficiency was my next thing, It's actually why I used the citrus fertilizer with trace elements after reading one of your blog posts. :thumbsup: I'll pick some up tomorrow. Thanks again, I really appreciate as a newby been able to come onto the forum to ask for help and advice. :twothumbsup:
 

Mark

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No worries Kate I hope the iron chelates helps - it may take several weeks to see an improvement.

These types of questions with good images are really helpful for everyone and interesting to see if we can find a solution that works (fingers crossed).
 

Mark

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Would a general plant fertiliser cover for such a deficiency, like the typical complete plant foods by Searles, etc.?
They do Ash yes for sure in standard gardens, but in certain soils that are missing specific nutrients or are balanced too far one way (eg too alkaline) a balanced fertiliser with trace elements might not be quite enough so adding an element separately in larger quantities may work better.

Iron absorption is also helped by facilitating a healthy or "active" root system (especially concerning citrus as they do like to have a fibrous root system close to the surface) therefore good mulching really helps and preventing nutrient erosion through heavy rain by slowing water rush through orchards via moguls or drainage etc works.

Also, we should be careful when weeding or clearing around the base of citrus (and other trees) so as not to disturb the surface roots eg brushcutting or tilling as damage to these roots will affect nutrient absorption.

Having said all that, it's not uncommon for a healthy tree to have a few leaves that are showing signs of nutrient deficiency, pest attack, etc and whilst we should stay on top of these things I personally don't aim for perfect trees because one runs the risk of "killing with too much love" when it's quite normal for a citrus to have blemishes.
 

Ash

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Sound advice Mark. Thanks. Killing with love could go both ways - we'd have to be careful not to overdo nutrient supplementation also as all minerals are toxic in higher quantities. I wonder if citrus are like people: we absorb iron better with vitamin C...
 

Mark

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I wonder if citrus are like people: we absorb iron better with vitamin C...
Yes, good advice also Ash and a good reason to eat citrus I suppose...

That does pose an interesting question whether certain other minerals or vitamins help plants absorb iron?
 

Ash

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Quite a different biochemical pathway from human or animal gut absorption of iron, but from my reading plants absorb iron in the inorganic form, finding ferrous iron (Fe2+) easier to absorb than ferric iron (Fe3+). So for example, a supplement of iron sulfate (FeSO4) is one of the best, but the soil needs to be slightly acidic to maximise absorption (plants don't do this well in alkaline soils).

There is a fascinating scientific article on the method of iron absorption here: http://www.nature.com/scitable/knowledge/library/plant-soil-interactions-nutrient-uptake-105289112 (for those interested in the physiology of it).
 
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Ken W.

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Alkaline soils lock up iron causing the deficiency signs you describe which is more technically known as lime-induced chlorosis. Check your pH, otherwise the iron chelates will only be a temporary fix. Citrus prefer the pH to be 6.0-7.0 but will tolerate a little outside the range. If the soil in general is alkaline this can be remedied with the application of ag sulphur. With the variance of discolouration of the different trees it may be tolerance levels of the varieties - mainly the rootstock - or it may even be as simple as the mulches you have used as some mulches and non-chemical fertilisers - mushroom compost and poultry manure for example - can cause alkalising of the soil.
 
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ClissAT

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I agree with Ken re the pH being out of balance. It can happen if the soil gets too dry then watered & redries.
It can happen like that during winter if the trees aren't hooked up to an irrigation system.
I would guard against using too much sulphur as that can throw out lots of other micro nutrient balances.
Most of the goodies are already in the soil, it's just a matter of liberating them. Sometimes micro nutrients can be spent if the tree is a gross feeder & citrus are gross feeders.
Lucerne tea applied over chicken manure pellets that contain a full spectrum of goodies is a really good way to liberate more nutrients in the soil.
Another way is to mulch deeply right out past the drip line with lucerne hay & keep it well watered for a couple months until it gets a bit slimy underneath.
That's the biology getting to work.
Humic acid will aid nitrogen utilization & help build in more moisture holding capacity to help prevent wetting & drying occurrences which citrus hate.
 
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