The plant itself looks very healthy imo.
This leaf has already been breaking off slowly over the last week(s) or so. It's one of, if not the lowest one, and I belive the stem is just growing so fast and thick that it might have been just ripped apart, so I don't worry about it.
Today, I noticed some powder residue sitting on the upper area, mainly the stem.
I highly suspect a fungal infection, most probably powdery mealdew.
And I mostly believe that it is just a stress symptom of the plant. I trimmed off quite a few roots and also forgot to water it a few times over the last weeks, because it's just SO thirsty due to all the sun it's getting now in the spring.
It sits in a hydroponic medium (semi hydro with LECA) and has been extremely healthy over the last few months. Still, this, and the high humidity fluctuations (one week 20%, the other one 80%!) were super stressful for it, so I don't wonder myself about this.
It also looks quite a bit dehydrated and nutrient burnt right now, but that will look better tomorrow.
Question is: Will there follow any leaves that will break off?
I think the mealdew problem is fixed quickly, maybe by itself if the plant recovers from the shock.
Should I worry?
Bananas do and will loose their bottom leaves as they grow, so no surprises there.
As you probably know the black flaky stuff on the outside is normal sap, not mildew. As far as u can see there is only mildew present where the frond meats the trunk.
As there is only a small amount of mildew and no signs of rot I don't think the mildew caused the leaf falling off (rather just natural growth). If it gets more chronic mildew it may cause issues in the future. We grow our bannanas outside and powdery mildew between old fronds is a given, and not a concern, however indoor plants are a lot more prone to disease so it may be a worry.
P.s. its not powdery mildew (mildew is white/grey). Its probably just some kinda mold that settled in the crack left by the leaf falling off. I would only be concerned if it is present between young fronds or starts rotting the trunk.
Thanks! That was very helpful!
Glad to be helpful :)