Dendrobium Phalaenopsis- sunken rings on the underside of old leaf

[snoozy]

Hi!
My first orchid- a dendrobium phalaenopsis type- is sick Sunken rings have appeared on the underside of an old leaf, at the base!
It has beautiful roots with green tips, and is putting out a new growth! Even bloomed for me this year...

Spots:
Attachments 1 and 2

Roots and new growth:
Attachments 3 and 4

It enjoys warm to hot temperature throughout the year.
Sits on a southern veranda, receives bright indirect sunlight!

Are all symptoms indicative of virus? Are there any other possibilities?

Thank you for your time!

[estación seca]

Welcome, snoozy!

I looked at your photos. I can't tell what that is. Virus infection can cause rings, but the ones I've seen in online photos don't look like that. I think it could also be fungus damage.

Is there a university near you with an agricultural department? They might be able to help.

Google Drive doesn't permit posting clickable links here. People can look at your photos by right-clicking one of your links, copying the link address, opening a new tab, pasting the copied link in the URL box, and going to the photo.

[snoozy]

Thank you for your reply estacion seca!

Unfortunately, I haven't found a place where you can get orchids tested in the area. I have been keeping an eye on the orchid ever since.

These are photos from 21st October. Notice the progress in just four days. The pace got me scared, so I cut them off. No new spots are visible YET. Fingers crossed!

[snoozy]

Probably shouldn't get my hopes up too high, but YAYYAYAY!

I am watching it like a HAWK. Will be updating if I see anything suspicious! Thank you so much for your input @jkofferdal!

[estación seca]

There are different fungus pathogens in different parts of the world. The ones I've seen here in North America don't look like this, but we have a very different climate from yours. Is there a Bangladesh orchid society, or a nearby society in India? Maybe somebody there knows more about local issues.

[snoozy]

I have contacted the orchid society of Bangladesh, asking for a way to get this orchid tested. Sadly, they don't test orchids, nor do they know of labs that do...

As for fungal problems, I fear they'll misdiagnose it. It's treated more like a non-serious hobby around here, orchid diseases go unnoticed. Maybe someday local orchids will see better days! Till then, well :P

Raising fighters

EDIT:
I'm looking for universities that would diagnose the problem. Meanwhile, applying fungicide and organic pesticide.

The plant stays far away from my other orchids (except for one that has always shared water with it, and hence is probably already infected). I'll keep posting pictures if I notice changes!

[estación seca]

I would pay attention to landscape plants in your neighborhood, and see whether any of them have similar lesions. You live in a warm and wet climate, so there are probably a lot of fungi that attack local plants.