Roslyn

Hi everyone,
I am growing several banana plants in a greenhouse and lately they have been developing big brown spots on the leaves, like this:

They are mostly pretty tall and from that particular picture, it looks like maybe the leaf has rubbed against one of the metal bars close to the ceiling of the greenhouse. Does anybody know if rubbing against a metal bar cause a brown spot that looks like that?

I don't think all of the brown spots can be explained away by rubbing against stuff though. I also have two young banana plants, maybe a foot or so tall, and they have brown spots on their leaves too:

One of the young plants even has brown spots on its cigar leaf:

There is nothing close to those plants that could have been rubbing against them. I have looked at some of the brown spots under a microscope, and I can't find any bugs or anything. Any ideas of what could be causing my problems? Thanks in advance. I am worried about my plants.
-Roslyn

Dean W.

Maybe to much fertilizer (salt burns) just a guess.

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Roslyn

Do you know if there is a picture on here somewhere of what fertilizer burns look like on banana? I guess it could be possible for the young plants, because we did mix in a little slow release fertilizer into their potting soil when they were transplanted to bigger pots, but I don't think the big ones have been fertilized in a few months. Hmm...

Dean W.

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Burned leaves?
cause of burnt emerging leaves in DC?
Where are you located? The light intensity may be changing and causing some abnormalities. Sometimes plants burn or discolor behind glass or polycarbonate. Mine have been affected though seem to be coming back to normal after changes in the weather.

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venturabananas

Roslyn, I wouldn't worry too much about it. It isn't caused by disease. Seems like there are several potential causes of the kinds of burns you're seeing. You can get symptoms like you're seeing from too much dry heat, too much wet cold, too much fertilizer, too few micronutrients, premature emergence of the leaf, etc. None of these will kill your plant in the short term, though you wouldn't want to expose your plant to any of them in the long term.

If I had to guess, the burns on your cigar leaf are probably caused by too much fertilizer. Essentially what happens in that scenario is that the cigar leaf emerges in a premature state, in the sense that the cell walls don't have sufficient calcium and maybe other micronutrients to deal with the elements (sun, cool, heat, whatever). The same thing happens sometimes if you chop a pseudostem way back and so the cigar leaf emerges well below where it would have had the stem been intact.

The burns on the older leaves could be from just about anything. From what you say, it probably isn't from too much fertilizer. Perhaps they were in contact with something hot or cold.

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MiamiNice57

Hmm the small purple spots look just like what my Juvenal ornamentals look like until they reach 20”

The bigger brown burned looking spots do seem like over fertilization “boron” and iron” can cause these spots.

Take a look at the slow realease fertilizer and note the minors.

Give it some water and time.
Hope this helps.

Keep us posted.

MiamiNice57

Honestly it looks just like a variety of ornamental I currently have to n my from yard.
It looks perfectly fine.

As for the new growth you may have bumped it at some point & not noticed it at all.
It doesn’t take much to hurt the leaves at that tender age.

If it is the ornamental type banana plant once it grows to about 2 feet it will lose all those beautiful spots & go a lush green

cincinnana

wow...this post is so old.
I hope the plant sorted itself out by now

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hseeng

Old post but I may have the same issue. looking for advise also

In February I gave this plant/pot a good water then applied about 1/2 cup (2-4 oz) of 10-10-10 granular fertilizer on top of the soil around the outside of the pot away from the trunk and any pups. At the time the pups where really non-existent. (about 1" high and haven't gown in 9 months). Week later the main plans leaves drooped. 2-3 weeks later all of the main plants leaves yellowed and slowed died off over 4-6 weeks. Mother plant stopped growing. 4 weeks after the heavy fertilization the pups took off and grown 3 pups that are 20 24" tall in 10 weeks. Main pant is still suffering. It also had spider mites (or still does)

I separated 1 pup 3 weeks ago
The 2nd pup looked great until now. As you can see in this photo something is impacting the leaves.

I think this is fertilizer burn of some sort.

Thoughts

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Newmarket, Ontario, Canada, Earth

cincinnana

The plant will do that for the exact reasons you mentioned.
Once outdoors it will sort itself out after a few waterings and new leaves.

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