Mesophyll Cell Collapse - Orchid Board

Shirley · #1 11-08-2008, 11:00 PM

For a couple of years I've been having problems with my phals. Many of the leaves are very pitted and discoloured so they are very unattractive. The plants have been tested for virus and are clear so I'm thinking it's cell collapse. Does anyone have suggestions for me, treatments, etc.? My minimum temperature at night is now 60 deg. (used to be 55) and I'm careful that the leaves are dry before nightfall. Should I be removing the leaves that are marked -- that is, does it spread from one leaf to another? Do I just have to wait for it to grow out? Thanks for any help.

Becca · #2 11-08-2008, 11:24 PM

Hi Shirely! Would it be possible to post a few pictures of the pitting? I would hate to recommend to take a leaf off if it doesn't need to come off and pictures would really help with a decision like that. If it is spreading, it sounds like it is bacterial.

calvin_orchidL · #3 11-08-2008, 11:55 PM

Hi Shirley

Do they look like the images on this site? I had something similar sweep through most of my phal collection...I went through an extensive search of different forums and articles when I first saw these symptoms, and I've talked about what I've found here and here (hopefully I don't get in trouble for linking to another forum :S)

Although it's still inconclusive WHAT this is, I can guarantee you that it spreads aggressively. All the phals in the common area got this disease and I have disposed of them. The ones in my second growing area were spared. Once a phal gets it, it's rather difficult to cure.

Carl Austin · #4 11-09-2008, 02:49 AM

If the disease Shirley complains of is the same one that Calvin provides pictures of, it caused me to throw out 1100 Phalaenopsis 10 or 12 years ago. A friend of mine threw out even more.

There seems to be a diagnosis of "microfungus" prevalent and even a suggestion that treatment with a systemic fungicide will stop the spread of the disease but it won't cure the already stricken plants. That was not my experience. I used both Benomyl and Funginex but nothing stopped the spread which by the way, was very rapid.

Is there such a thing as a "microfungus"? The name sounds like it was invented by someone because there was no real diagnosis. Has anyone ever heard the term with reference to any other situation?

Carl

Undergrounder · #5 11-09-2008, 05:58 AM

wow that sounds horrible...

my guess is they said 'microfungus' just to distinguish it from normal visible fungi, being 'macrofungi'. So in other words another name for a fungal infection

calvin_orchidL · #6 11-09-2008, 11:20 AM

Carl - that's terrible to hear...and I thought I had it bad getting rid of 20 plants. You are right - the spread is incredibly rapid.

I think microfungus is a catch-all term to describe the infection, but I have a feeling that it may be an opportunistic infection that takes hold because something else is wrong. As I mentioned in one of my posts, I did get one phal tested for virus and it was positive with cymbidium mosaic. Perhaps it is the viral infection that makes the plants susceptible (although Shirley's plant is disease free).

camille1585 · #7 11-09-2008, 11:44 AM

That sounds like a terrible devastating disease! I have never heard of the term microfungus before, even in scientific literature, so I think it's just a way of putting a name to the disease. I pray I never see anything like that on my phals. I know that in France it is possible to have regional plant protection services help you out with such things. You send samples to their lab (for a fee) and they will identify the pathogen. I think they intervene in the case of serious problems only (since they mainly work with professionals), but this would probably qualify as being serious! I don't know if it is possible to do that on your side of the pond. It might be worth looking into.

Ross · #8 11-09-2008, 01:45 PM

While I also feel it is very devestating and unfortunate, I can't help but wonder where it came from? Does this stuf just blow around in the air? Does it get into the pores of the leaves? Does it come in with previously infected new aquisitions? We need to determine what happened. I'd hate to think my collection is at risk, even though it is apparently disease free right now.

Shirley · #9 11-09-2008, 05:42 PM

Attached are photos of three of my phals. This does look quite a lot like what Calvin describes but doesn't seem as invasive (doesn't progress as quickly) and hasn't affected the blooms. New leaves coming in look good, making me think I have it licked, but a few months down the road the markings seem to start again. You can see this in the third photo. I've used fungicide and Benomyl though not on a continuing basis and I've also used alcohol and listerine on the pitting. I'm not aware of having brought in any unhealthy plants. It seems to have developed in my plant room. At first I was told that it was just cold damage which is why I upped my minimum temperature to 60 deg. I'm about ready to try anything so I hope some of our experts will have suggestions. Help! Help!

Carl Austin · #10 11-09-2008, 10:27 PM

Looking at the photographs as well as the fact that the new growth is not immediately affected, leads me to believe that your plant has the same disease that caused me to throw out so many plants.

I recommend you throw it away ASAP before gets in the rest of your collection.

I'm sorry but that is the best advice I can give you.

Carl