phalaenopsis cell damage

[djm]

Hello everyone,
I am writing because I would like to have your point of view on what is happening to my orchid.

i have about 15 phalaenopsis, some have dehydration issues but everything under control. The are in a sort of little "attic"m with 2 windows on the ceiling to maximize available light; they have "sun-protection" curtains, that protect from direct light leaving all the brightness coming in. The ones with dehydration are out of the potting media, hanging under an open plastic bag, hanging with tray of water underneath. I brought them few steps downstairs as the air might become too dry sometimes up in the attic.

So, this is to have a mental picture of what is the environment.

I spend almost every day some time with my plants, and one day I saw one healthy plant showing the upper (newer) leaf with a yellow stripe in the middle. I thought that maybe a ray of direct sunlight reached her for some reason. I moved her a bit away from the others. In about 2 days, the leaf was completely yellow and dried out. I saw light damage before, and this was too fast...
I cutted it with sterile scissors, and kept an eye on her.

A couple of days afterwards, the biggest leaf right below the one that died started to show unusual sign of sickness. It started to turn yellow in the middle, then cells started to collapse, and some areas turning brown-ish. I will attach pictures. In few days, half of the leaf looked like it had an herpes: all "bubbly", half necrotic. by that time, the plant was isolated in a corner trying to give enough light but stay away from others. I pulled her out of the pot: no issues on the roots.
As I had one of the new plant with some white fungus, I sprayed the sick leaf (well the all plant..) with anti fungal, but noting. The "thing on the leaf kept going". Last night decided that, even if it hurts my hearth to do it, I'll cut the leaf because if it is an infection better lose a leaf than the plant. Felt like a surgeon: gloves, sterile cutter, cinnamon if needed for root inspection, dedicated tray to work on, bag for possible contaminated media to throw away...

......but I believe that the infection spread to the other leaf as well, as the are showing little sign of this "herpes".. I am feeling so bad, this plant was perfectly healthy, the flowers were time ago cutted to let her recover in the new environment, and now she has a new flower-bud coming out!!!

I do not know what to do. I do not know what it is. I have not seen anything like this ever, even online....

If any of you had similar experience please share it with me...

Thanks a lot,
DJ

[Discus]

Hi DJ, this looks a little bit like something I've seen called "mesophyll cell collapse" - it is usually triggered by cold. Do you have a maximum/minimum thermometer in that room? It can get very cold near a window at night, so perhaps make sure this isn't happening. I don't let my Phalaenopsis get below 10ºC. Even if it's not getting that cold, if there is water sitting on a leaf, evaporation can chill a leaf sufficiently to cause damage if it is close to "too cold"!

Bonne chance!

[djm]

hi Discus,
thanks for your quick reply.

The "attic" has the most stable temperature int the house. During the day, it doesn't usually get warmer than 25 degrees, while at night it never goes below 17-18 (even in winter).
The plants are about 1.5 meters below the windows, and when I am at home i open a window about 6 meters away to circulate some air.

I would actually love to have someone taking care of me as much as I do with my orchid!

[Discus]

Here's a longer article on mesophyll cell collapse (second half of the PDF) http://www.saskorchids.com/newsletters/200809.pdf

It can take some time for the damage to manifest, so the cause may have been some time in the past (like if you went away on holiday in winter, and switched the thermostat down, the damage may only now show up).

People with more phalaenopsis than me may have seen some other causes of this, but that's the only thing I can think of.

Another potential cause may be oedema from too much water at some stage, but this is unusual.

Even cold (tap) water in winter can cause damage; it's worth using slightly warm water, or at least "room temperature" when you water tropical orchids like phalaenopsis, particularly in winter.

---------- Post added at 11:24 AM ---------- Previous post was at 11:23 AM ----------

p.s. I was intrigued by the Cisco box in the last picture.

[djm]

thanks, the article you sent was very interesting.... but wow! "think back several months"...?? .. this could have been the time the plant was purchased, and in here it has been snowing until april. It could be that the plant was exposed to quite some cold, but only 1 or 2 minutes in total, time to go from the shop to the car, and from the car to the house.... Can it really get damaged for this short exposure?....

in this case, did I cut a leaf (well... half dead leaf) for nothing??!.. should I do something with the little very cute flower spike that is coming out, to help the plant to survive..?


PS: yeah, my Cisco equipment needed a gentle touch, that's why the orchids are in the same place

[Discus]

I think you can probably leave the spike on the plant. Keep a close eye on that disfigured area; if it spreads, or starts looking nasty (particularly weeping fluid), it may have been infected with bacteria or fungi, in which case you'll need to treat it.

As to whether the shop>car>house exposure to cold could be "enough" to cause damage, it really depends on things like just how cold it was outside. I'm sure if you took an unprotected phalaenopsis outside in Moscow (-40) in mid winter for a couple of minutes, it would die/suffer greatly!

Good luck with the ciscos, they can be tricky little beasts.

[james mickelso]

Don't overlook fusarium wilt. Look it up on the net.

[djm]

Thanks for your reply James .

Fusarium oxysporum seems to be related mostly to fruit plant, at least based on wiki.

I cutted the big (...sigh.. ) infected leaf, and treated the plant with antifungal.
Now I am waiting to see what the remaining two will do...

I'd like to find what is that "sucked up" this plant, in case it spreads to others..

[james mickelso]

Fusarium wilt attacks phals and other orchids. Very bad stuff.

[Brooke]

I thought the fusarium bacteria only occurred in the soil? Do you have the Phal planted in "dirt"?

Brooke