Phal: Black spots with yellow on leaves

[TracyLee9]

Does anyone know if I need to be concerned about these black on yellow markings? Firstly, along the leaf crease in the middle and then towards the base on the edge. I bought this orchid form the nursery 2 weeks ago, but only noticed the markings now (and only because I had some drama on a subsequent new orchid that made me really inspect my existing orchids – see Transport disaster post if interested, eek!!). I reckon these markings were there when I bought it.

I’ve been reading up on other black spot posts and it sounds like maybe this is a bacteria/fungus, but I’m not sure, hence writing this post. If it is a bacteria, looks like I’ve caught it early…but now what? Cut it, spray it, wait first to see if it spreads? And how does it spread? Do I keep it separate from my other orchids? Can I transfer it from one orchid to another just by touching it and then touching other orchids?

[TracyLee9]

Uh-oh...just got home and it seems it is spreading...and as I was taking a closer look, I noticed a horrible smell. Yikes!! What do I do? I think I need to do it quickly!

[NYCorchidman]

Cut it off. Wash your hands. Keep the plant away from other plants.

[TracyLee9]

The whole leaf? Oh no, that sounds drastic. But if it will save the plant...

No need to spray then? (eg. the other leaves, othe plants across the room)?

[NYCorchidman]

No need to spray.
That looks like some kind of infection, whether it is bacterial or fungal.

Removing the leaf usually takes care of the problem when caught early on, which is right now!

[lepetitmartien]

If it stinks: bacteria.

If the leaf has issues, you can bet others may have the bacteria too (Acidovorax maybe). I'd disinfect the whole plant if there's any sign of another attack (or right away), with peroxyde, physan or on the softer side cinnamon decoction (not on roots for this last one!).

It spread by contact, with water splashing or evil human fingers, and will attack on injuries. Use a sterilized tool, cut cleanly and large (here, it's easier to cut the whole leaf) beyond the yellowing part. do not touch plants afterwards before trashing the cut part, and cleaning yours hands thoroughly (alcohol can help).

Apply cinnamon on the cut.

[TracyLee9]

Ok, so I've cut the leaf off with a sharp razor that I cleaned with alcohol first. I then put cinnamon on the wound. Some cinnamon did fall onto the roots (why is that bad?) so I blew it off. Then I noticed a couple of black spots on the edge of a second leaf, so I cut around that too. See new uploaded pic of the results. Does this look ok?

[TracyLee9]

It looks like I should try your disinfectant suggestion too. The other leaves have a couple of tiny spots on them now too. You can barely see them, but they definitely weren’t there before.

My husband went to the nursery for me, came back with a fungaside. Apparently that's all they had. Will that work? The leaflet says it works on black spot, rust and mildew (it's not specifically for orchids though). Or perhaps I can try your cinnamon decoction - how do I do that?

Really bummed that the nursery sold me an infected plant...I almost feel like taking it back! Next time I will pay more attention. So many lessons to learn...thanks for the advice!!

[lepetitmartien]

It's bacteria, so a fungicide won't do.

You can apply sulfur powder on the marks, drench is peroxyde 3%, physan…