My Mandarin tree has pale color leaves..

johnthelandlord (Los Angeles California, Zone 10B)

7 years ago

Hello,

I have had this Mandarin tree for 23 years (not sure of it's age) and it had always had dark green lush leaves. The past two years or so, most of it's leaves have turned light green and some of the leaves on top have turned canoe shaped. I know it has some sort of deficiency and had tried increasing the fertilizer Miracle-Gro Shake 'n Feed® Citrus, Avocado, Mango Plant Food and also had cleared out a large plant and all the weeds around it. Nothing seems to help. It has always given excellent delicious fruit. Crop seems to be large this year. Any help would greatly be appreciated. It's located in Los Angeles. I have attached several pictures.

Featured Answer

Ike Stewart

7 years ago

last modified: 7 years ago

My guess from the photos is that it needs Nitrogen, it may also be deficient in something else, it looks like Magnesium deficiencies to me based on the leaves, though I would not expect to see that in the calciferous soils that are commonly found on the west coast. Soil pH effects nutrient uptake, so the first thing I would do is do a soil pH test, get home pH test kits for under $10 in most garden centers. This includes a small capsule of powder that you mix with a soil sample and water then compare colors on a chart. Do note if you have recently fertilized the soil it can throw off the readings if your soil sample is contaminated with any granuals of the fertilizer. (Don't trust he cheap electronic probe pH meters).

If your soil pH is above 7 I would suggest the first step being to fertilize with a fast acting Nitrogen source, my first choice would be Ammonium Sulfate, available at better garden centers, Amazon, etc. Just be ware it can cause fertilizer burn if used too strongly. Or Calcium Nitrate if soil pH is below 6.5, though I think the chances of this are VERY low for southern California. If you want to stay Organic use Blood Meal as a fast acting Nitrogen source, though it is a little slower acting than the other two mentioned above.

If you do need Magnesium, common unscented household Epsom salts are a great source of it, you can probably add a bit without much chance of overdosing, if you want to try just sprinkle half a cup of so evenly around the tree.

p.s. if your pH is above 7.5 or 8 you may also have Calcium induced Iron Chlorosis, the solution is to add iron using something like ironite, and lower your pH over time through the addition of Sulphur, this is a long slow process though.

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Comments (8)

charles kraft (SoCal 9B)
7 years ago
Memory from a long time ago - foliar iron works well on citrus. I'd try that.
johnthelandlord (Los Angeles California, Zone 10B) thanked charles kraft (SoCal 9B)
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CA Kate z9
7 years ago
It needs more fertilizer than you are giving it.

" A mature tree will require 1 to 1 1/2 pounds of actual nitrogen each year. This is equal to about 5 pounds of ammonium sulfate. Apply one third of this amount in February. Repeat twice more at 6 week intervals." Master Gardeners of Fresno County

This works for my citrus.
johnthelandlord (Los Angeles California, Zone 10B) thanked CA Kate z9
lgteacher
7 years ago
How long ago did you apply fertilizer? It takes some time to work. Be sure to apply fertilizer at the dripline, not around the trunk, or use a foliar spray of chelated iron, as mentioned above.
johnthelandlord (Los Angeles California, Zone 10B) thanked lgteacher
johnthelandlord (Los Angeles California, Zone 10B)
Original Author
7 years ago
Hi everyone, thank you for your suggestions. I had applied the fertilizer pretty much on a regular basis for the past 3 years or so per the instructions and around the dripline. What I don't understand is that why has the tree been absolutely fine with no fertilizer at all for almost 20 years? I would only guess that the large plant under it had gotten so large that it was sucking it away and that's why I took it out. I will get a soil PH test kit as Ike suggested to see what's going on with that.
Ike Stewart
7 years ago
What is this about you taking out a large plant, this is the first we are hearing of it. Perhaps in the course of removing a nearby large plant you injured the roots of the citrus tree. Citrus tends to have mostly shallow feeder roots that spread out some distance from the tree.
johnthelandlord (Los Angeles California, Zone 10B)
Original Author
7 years ago
To clarify, I took out the large plant after the pale leaf issue had already started a while back.
CA Kate z9
7 years ago
I had copied an article from a handbook for my last post, but normally use a balanced citrus fertilizer with all the proper nutrients, making sure that I give enough of the required nitrogen. I used a liquid one this year that seems to be working better than any: Urban Farms, which I buy online. I was thinking that something liquid might give your plant more immediate nutrients.