All summer most of my bananas have grown well, but after a week of no rain in the Florida heat, I watered a little with my sprinkler. About 2 tenths of an inch worth of water. Next day one plant's leaves had yellow swaths on them, others just had yellow midribs. I watered using my well last winter and this didn't happen, but this has happened before. I had suspected that my well water was sometimes hurting my plants, sometimes not. It all makes no sense. It's frustrating. Other people plant bananas, water them, fertilize them then eat them. Why is there always some crazy issue here for me?
See first, my Paggi, which has not been growing too strong (Don't know why), but growing... It was all green before the watering and that is not sun on the leaves or some camera glitch, it happened overnight after watering...
This is one of my Goldfingers. It was growing like crazy all summer until I watered it with the hose. It's growth nearly stopped, then began again, slowly. Note the one leaf pointing upward... green midrib. the rest have the sickly yellow midribs which also happens overnight after watering.
Then there is this guy... My VC. it is probably not going to make it. It was growing pretty nice until a critter tore it up last winter... It has never been the same. My guess is it has the black stuff on the corm like the PC I had near it. (Which also was torn up and never the same.) I am testing a radical replanting on the PC to see if it fixes this before I move anything else. I dug it, cleaned the corm and soaked it a few minutes in a 1/4 cup bleach in 3 gal of water then rinsed and replanted elsewhere to see if that fixes it. It is still too early to know. I already tried a groundsoak with antifungals on the VC, but it has not seemed to help. It is still early, though. It seems to me that SOMEONE on here has seen this problem somewhere before and have an answer at least of what it is. Please help.
VC...
Here is the pic of the PC with the black stuff on the corm and root die off...The VC likely has the same issue.

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Varieties I supposedly bought: Manzano, Cavendish, Blue Java, Sweetheart, and Gros Michel.
What it seems I actually have: Brazilian, Cavendish, Namwah, Dwarf Red, Gros Michel, Pisang Ceylon, Veinte Cohol and SH 3640, and American Goldfinger. FHIA 1, Paggi and FHIA 17... Always room for one more.