engelis,
Markings on leaf similar to fungal signs.
It could be a fungal issue and if so the plant would have to be treated with a fungicide. Keeping it from getting a lot of excess rain might help. In your climate the humidity should not be the particular cause.
Check with a local horticulturist or nursery, if possible.

Some others may have more information here.
Rick

Thank you rcharles for your advise. I think your right because its wet season in our country. I already relocated them and applied some natural fungicide.