I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
Very strange about your mango. I suggest you speak to your County Extension Office as the are up to date about specific problems that might be affecting those plants in your area.
For more on growing a mango in Florida see the following web site:
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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