Renantheras virus/sunken dark spots - help!

[mpiggy]

Purchased this Renantheras about 2 months ago while it was going out of bloom (see picture).

It is kept in a warm room w/direct sun in a south facing room in Maryland. I had repotted it in a vase half way filled with water to encourage humidity around the roots. The plant itself is planted in a pot filled with lava rock that sits in the mouth of a 1/3 filled vase. The vase water does not touch the roots or the pot. However, I can see humidity droplets inside the glass of the vase. I water every other day with very weak fertilization. This technique has worked well a vanda.

I returned home after a 4 day work trip this afternoon and was alarmed when I saw the leaves (see pictures). The room temperature may have dipped down to 50 degrees. I know I need to intervene immediately - but not sure what I should do.

1) I plan to remove the diseased leaves and spray with physan.

2) Should I also repot in coarse orchid mix? And try to grow it more similar to my thriving phalenopsis?

3) What roots should I be focusing on? Those in the pot or those growing a foot above the plant base?

This is my first Renantheras. I have about 10 phalenopsis and 5 catleyas that grow/bloom fine for me. I keep a vanda is a similar vase set-up. This is my first major case of a virus and I'm alarmed!!

Please advise.

Thanks!!

[RNCollins]

[CPKidofAugusta]

First, Renanthera is the singular. Renantheras is plural.

Pedantry out of the way, if it's true that it got near 50 degrees I would check out mesophyll cell collapse: Mesophyll Cell Collapse

[Leafmite]

I had to look this one up. Some of them seem to be warm to hot-growing orchids. It looks like everyone is right. Just be careful that a fungus or bacterial infection doesn't set it and it should be okay.

[gngrhill]

Looks kinda like sunburn to me. I have had multiple plants do similar and it has been sunburn and new leaves are fine

[lepetitmartien]

A sunburn on Renanthera…

For me it's spidermites and/or fungus. I'm more balancing on fungus.

I'm not sure the mode of culture is adequate, though here I'll let people more akin with Renanthera to care on this issue.

[OliverSparrow]

Impossible to tell from the photos. The mesophyll cells have died, but why is anyone's guess. Some possibilities:

* Sugar ants look harmless, but they bite leaves and such sap. The result can be simialr, although it's generally more "dotty".

* Thermal shock. Cold often causes monopodials to drop all their leaves, seemingly intact. Heat, though, notably with direct sunlight, can cause similar lesions.

* Interstitial bacterial. These result from mucky compost and or root damage by millipedes, sow bugs, slugs etc. Remove from the weird pot, soak in physan for a couple of hours, mount it like the deity intended on a lump of cork. The larger Renantheras (-ae?) are brachiating epiphytes, meaning that they use branches to stay aloft, but not out of any affection for wood..

[Vanda lover]

If the plant was too close to the window when the sun was full, it could get that kind of damage. I burned my asco leaves that way.

[HighSeas]

I grow Renantheras and you CAN burn those plants who have not been acclimated to strong direct light. It's hard to tell in the pictures but does look like a burn.

Either way...I'd soak him in physan or even better, Thiomyl for 15-20 minutes. Thiomyl is systemic. Follow up with the same soak in 7-10 days. I'm not sure I'd leave him in that vase either.

Good luck! Please let us know how he's doing!

[tryingtoflower]

I have one that has similar damage and mine is definetly sun damage.