Vladimir, I wonder if those leaves may not change even though the tree is healthy. I have a key lime that I adopted from my neighbor that has leaves like that and no matter what I have done, they have not improved. I even did a total bare root on it about a month ago. It is now budding and seems happy enough, but the leaves still look bad. I would keep doing what you are doing and check the new growth to see if they look healthy.

Picture 2 is a magnesium deficiency, apply Epsom salts either foliar or to the roots. Picture 3 is a manganese deficiency, you can apply a soluble manganese if you wish. If it was my tree I would do nothing. .

Here are pics Vladimir...

Vladimir, as you know I am not a big container guy, however, I have a tango mandarin growing in a pot that I use grass fertilizer on and it seems to be doing wonders for it. It is called turf supreme by simplot. I have also been experimenting with it on my in ground trees, mostly lemons because they're so hungry, and it has made the trees I've used it on a deep dark green color. It's heavy on the nitrogen but still a 4-1-2 make up which is pretty close to the 5-1-3 that citrus like. Here is a link to the technical sheet for the fertilizer. It only comes in 50 lb bags but I have a lot of grass so I use it on that and then dose my trees at the same time. Hope this helps.

http://techsheets.simplot.com/Best/74025_turfsup1668.pdf

Evan

My calamondin tree developed leaves like your page mandarin but it didn't heal those leaves. It sprouted a ton of new new growth and then dropped the worst of the leaves while the moderately damaged leaves are still on the tree. The new leaves look perfect and have grown in really fast but there are still empty spots on the tree.

John, in your above post, what you wrote is true to a point (Is = New & Old = Was). However, this does not hold up for the trace minerals that are mobile ......example Magnesium. In the case of Magnesium during a deficiency the old leaves transfer their magnesium to the new tender leaves in order that the new vegetation is not harmed. In the case of all mobile trace elements the old leaves tell you how the tree IS.

My Nagami kumquat has the same thing going on as your Page mandarin, Vladimir. I'm glad you posted. I really neglected fertilization this Winter on this one, and now the plant is paying for it.

Silica, you say you wouldn't worry about it? I'm fertilizing regularly now, and figure the new growth will be fine.

I've got kumquat seedlings, and 2 of 10 are starting to show manganese deficiency. I thought warm weather was supposed to help. I probably under fertilized them, tho.

You mentioned that you discontinued your vinegar regimen. Vinegar can work if your water isn't too bad but ph is far more important than the brand of nutrient you give them. I tried the vinegar thing as I had read it repeatedly on forums, but suffered mediocre growth, deficiencies, and generally declining health on my citrus until I bought a ph meter and found out the water running to my house was 9.4-9.6. It hit me like a brick how silly it was to worry about fertilizer and the extra 0.001% of a certain nutrient that one brand has over another when I was going blind on the most important factor of citrus nutrition.

I treat my water with diluted sulfuric acid in 20 gallon tubs and run a consistent 6.0 but will toss in a week of 5.5 or 6.5 just for fun every now and then to give all the nutrients a chance to hit their sweet spot on the ph chart. All my trees flushed immediately and I was in disbelief that a citrus tree could put on two feet of growth in the span of a couple weeks. At $40 for a lower end meter, it was by far the greatest return on investment dollars I've experienced in gardening.

Your water is probably nowhere near as bad as mine, but if you're getting deficiencies while fertilizing - ph is your problem. Give it a good spraydown or two with a micro foliar and be strict with your ph and it should clear up beautifully. Agricultural Sulphur will do the same thing without all the hassle but it's guesstimation at best and takes time to start working. Good luck and I hope that helps.

Vinegar is a weak organic acid, consisting approximately 7 - 10 percent acetic acid (CH 3 COOH), Being an organic acid it has a short life span. As robe951 wrote above sulfuric, or as I prefer, phosphoric acid, works much better. I purchase phosphoric acid in 15 gallon carboys, which last me quite a while. It is injected directly into the irrigation water using a Dosatron fertilizer injector.