Disturbing leaves on D unicum and D Delicatum

[Harris E.]

Hi Everyone

Just a couple of days ago I noticed some leaves yellowing on my D unicum. I wasn't too worried since it had been getting a lot of sun recently so I just moved it to a shadier spot in the greenhouse. I took another look today and the leaves really look bad - much worse than before. Please see the first two pictures I attached. It seems to be affecting all the leaves on the plant including the ones on the new growth. To top off the bummer, the same thing is beginning on my D. moniliforme which hangs above the unicum in my greenhouse. Has anyone seen this before?

Also I found a brown ring surrounding a brown lesion on my D Delicatum leaf (see third picture). Any chance this isn't a virus?

Yuck.

Harris

[Leafmite]

It doesn't look like a virus to me.

[astrid]

The delicatum leaf absolutely looks like a virus to me. I would simply toss a plant like that- that is extremely concerning pattern. (I am NOT an expert, but that target-shaped pattern is really remniscent of a ringspot type virus to my untrained eye)

The unicum looks more like a bacterial or fungal issue, but may also be a virus. I would get rid of these ASAP.

Here are some resources you can check out if you think you want to treat the plants:
Powerpoint summary of many pests, bacterial and fungal infections, and viruses of orchids

spreadsheet of pests and treatments of each

spreadsheet of bacterial/fungal infections of orchids and their treatments

Both those spreadsheets are in the powerpoint, but they are very difficult to read.

You should throw those away and buy healthy plants!! If you just got them, message your vendor so they can know something is wrong. There is a chance you could get a replacement plant or a refund if these are recent acquisitions. Dendrobium unicum is easily found online.

I'd rather just buy new ones than risk making my other plants sick. Good luck with whatever you choose to do!

[gnathaniel]

I'd guess the unicum is suffering from a fungal infection. The Delicatum leaf looks like it just got sunburned, try increasing air movement to keep the leaves cooler.