What's happening to this Medinilla?
It is inside in a very luminous position but not exposed to direct sunlight, the vase is placed on a saucer containing expanded clay to create moisture. It is irrigated with demineralized water also used to vaporize the leaves once a week.
No parasites appear.
Medinilla magnifica problem
Looks to be it is burnt to me. If you wet the leaves then the sun hits it esp thru glass, leaves can get burnt. Are you sure the sun never hits it?
Is it on more leaves on all sides of the plant?
Sounds like you love this plant. I do too!
Ciao! Thank you for your answer!
I think it's one of the most beautiful plants in existence: I love it !!!!
The plant is on a shelf located on the wall opposite the window and higher up where the sun's rays can not reach it directly.
I had never seen a similar problem and I also thought it was Botrytis cinerea.
Sadly, I am no expert. I guess it could be similar to this leaf damage from Botrytis cinerea. https://www.greenhousecanada.com/inputs/crop-protection/march-april-2014-4022
Do you have a good nursery near you? Often they will opine on plant issues if you bring in the leaf in a plastic bag.
Good luck. I hope you can cure it. Come back if you get an answer and tell us.