Possible bacteria infection on Cattleya dowiana leaf.

[DavidCampen]

I recently noticed this large spot on a Cattleya dowiana ('Maku' x self) that I acquired 3 months ago. The plant tests negative for CymMV and ORSV by an Agdia Immunostrip test. I am guessing that it is a bacterial (Pseudomonas) infection.
Orchid Diseases

I will treat with Bonide Liquid Copper Fungicide (copper octanoate 10%), 8 ml per liter.

I see that the Bonide Copper Fungicide label says that it is "For Organic Gardening". I wonder if I could get copper acetoarsenate approved for "Organic Gardening".

Scale in photo is in centimeters.