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Mango #1 Picture Gallery

Mango #2 Picture Gallery

Mango #3 Picture Gallery

I have had previous problems with Mango #1 and posted here a while ago, link here

I have 3 mango trees I am growing from seed that are approximately 6 months old now. They all have the same watering schedule of approximately 5-7 days per watering. They've only been in 68F (20C) - 74F (24C) their entire life in a grow tent with a 2000W grow light approximately 38-44 inches away from foliage. There are 2 auto-rotating fans in the tent. The soil composition has been 6 parts Miracle-Gro soil for Trees, Shrubs, and Bushes to 1 part coarse sand.

Mango #1 has displayed these grayish-orange spots for about 2 months already and have been getting worse over time. I've thought to this day that it is a fungal issue so I bought "Serenade Garden AGRSER32 Disease Control Effective Organic Fungicide" and been applying to foliage with a sprayer as directed by the bottle for about a month and a half. I haven't noticed much happening but at the same time I don't know what I should expect to see to know "the disease has been controlled" as I wouldn't expect the affected foliage spots to recover.

A month and a half ago, I gave 2 tablespoons of "BGI CitrusFood" fertilizer to all three of my mango trees. For some stupid reason I thought it would be a good idea to give an extra tablespoon to each of my mangoes 2 weeks after the first fertilization. I noticed a few weeks later that on mango #1 and #3 some of the tips started to blacken and it slowly grew. From some research online it looked like it was salt toxicity (or so I think). To try to solve the issue I tried to heavily water them when it came time to water them on their schedule to drain the soil so salt wouldn't sit. That wasn't working. I then tried to give a distilled water flush but that didn't seem to change the problem either as the problem kept progressing as the days went on.

A few days ago I decided I had enough and I transplanted only #1 and #3 into brand new soil which is 6 parts "Miracle-Gro Moisture Control Potting Mix", 6 parts "Kellogg Organic Plus Plating Soil for Trees, Shrubs, and Roses", and 1.5 parts desert sand.

As of a few days ago #2 has started to show one little black tip on a leaf and another leaf indicated by the red circle showing a larger blackening effect. I'm thinking of transplanting #2 into new soil as well as I don't want to increase the severity of what I believe is a salt toxicity problem in the soil.

Mango tree #3 had 5 leaves prior to the second fertilizing round in the old soil and 2 brand new leaves. (Sorry I don't have pictures for this) Typically when new foliage grows, it starts off as a deep purplish-red color and slowly progresses into a mature green foliage however these two new leaves didn't have any purple and grew into a similar sized foliage as the remaining two on the stem in the picture album. The tips started to curl and brown/blacken until the two new grown leaves fell off the stem. The entire leaf was a very light greenish yellow with all the veins of the leaf having a healthy green color. There were no abnormalities with the vein sizes. The leaves prior to the new foliage falling off was starting with the oldest leaves first if that helps. I believe it is the same "salt toxicity" problem in the soil but would really like some reassurance that I'm on the right path with saving #3 since it is in the most vulnerable position.

~Does #1 have a fungal disease besides the blackening tip problem or do I have it completely wrong and it is a nutritional problem instead?

~Are the blackening tip/curling leaves problem with all three of my mango trees a salt toxicity problem or is it another problem after all?

~Anything I can do to increase the chance of Mango #3's survival?

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Similar to other large-pit stone fruits like avocado, mango can get a lot of nutrition from the pit during the first 6 months to a year of its life. Eventually the roots have to take over and look to their soil surroundings. Note that in their blurb Miracle Gro advises that their Tree Shrub soil is "not for use in pots and containers"; look in the product specs. Their use instructions say to mix with equal parts of regular garden soil and plant in that mix. It was a good idea to mix in sand, however I think you still ended up with a poor mix for the mangoes. At this stage it is probably not too late to move to a mix of regular garden soil and sand/grit (3:1) and if possible allow the plants to breathe fresh air and drink only rainwater mixed with occasional weak feed in a sunny window. Right now it sounds as if it is overprotected and (please forgive the blunt metaphor) sitting in soiled nappies.

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    Do you happen to have any idea what is going on with Mango #1's leaves? I can't tell if it is a nutritional problem or a fungal problem and if so, what? – AmateurMangoGuy May 14 at 20:28

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