Black spots on several orchid leaves
 

Is this a fungus? I had these black spots on one of my vanda leaves when I got it, and I assumed it was mechanical damage. Now, several months later, I’m not sure if I am noticing more of them or if they are spreading, like a bacteria or fungus. I have attached pictures of my vanda, cymbidium and cattalya.

Can someone identify what this is and treatments? Thank you.

The Cymbidium has spots like they often get. I wouldn't worry. The spots with light brown centers are probably scrapes. I can't see the others well on my phone. Go to the Web site of the St Augustine Orchid Society and look up fungal infections on Vandas to see if anything matches.

You know I was just on that site a few minutes ago. It is so difficult to tell. It looks like it might be Phyllosticta or Guignardia leaf spot but it’s hard to tell. The treatment for that is copper spray, and I have Mancozeb so I could treat it with that, if I was sure that was the actual problem. I don’t want to treat unnecessarily.

I’ve also noticed black spotting on the leaves in my oncidium. Pictures attached.

I wondered about those two but didn't have the plant in front of me. Oncidiums usually have a few spots like that.

To determine if they are spreading, you could draw a circle around them with a sharpie. Then you can see if a spot changed with respect to the line.

Ok I’ll try the sharpie method. It doesn’t seem like the oncidium is much to worry about. I will keep an eye on it and spray with copper if it seems like it’s spreading. Thank you.