Banana's love water and are heavy feeders,have you given any food? have you amended the soil lately?

Maybe it's a nitrogen or sulfur deficiency. Also, possibly, glyphosate injury from herbicide spray drift but you would have to get a lot on the foliage before symptoms appear.

If I were you, I would water with 2 tbs. of ammonium sulfate in 2 gallons of water and wait 2 weeks to see what happens.

Hello!

@christine - I have put Palm Tree fertilizer stakes into the ground about 1.5 years ago, nothing lately. I was afraid of burning them with too much. Thinking about watering with some plant food, like Miracle Grow, what do you reckon?

@aruzinsky - why should I water it with ammonium sulfate?

More photos!

No roundup, that fence is not shared with neighbors

Then, sorry, I don't know what is causing that strange yellow pattern.

Based on your comment I would say too little water is the cause or contributing to the cause. . Water it every day if your daytime temps are in the 80's or 90's.

maybe you are watering it with tap water? chloride/chloramine in water might be cause of this. it would kill all beneficial soil bacteria/fungi and then the bad ones take over causing diseases and weak plant. i would suggest treat soil with beneficial bacteria, then mulch on top, and then water it only with rain water. but this thread is old so most probably that banana died already. in hopes of new ones growing better:)

or maybe neighbors have swimming pool behind the fence...