Thank you very much for the information and your warnings, Estacion Seca. I just thought that Banrot was effective for this type of fungus. I bought it years ago from the USA. Here in Europe, it is difficult to find some of the fungicides commonly used for leaf spots (Daconil, Cleary's 3336, Pageant, Heritage are recommended at
St. Augustine Orchid Society - North Florida Orchid Growing), and I have no references as to what their equivalents are here. Perhaps some European grower can help me. Thank you very much again.