I use Bonide copper soap on my cattleyas, and laelias and a couple of stanhopea and gongora with no ill effect.
Bonide Liquid Copper, Bonide Liquid Copper Fungicide Concentrate
This product is 10% copper octanoate.
It is said that copper is toxic to dendrobiums and bromeliads and stanhopea and gongora. I have kept the copper soap away from my few dendrobiums. It has not harmed my stanhopea or gongora and the other weekend I accidentally sprayed a tillandsia (spanish moss) with copper octanoate, I hosed off the spanish moss later and it has shown no ill effects.
I suspect that the Phyton product which is copper sulfate may be more phytotoxic than the Bonide copper octanoate.