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Bacterial brown spot on Colmonara

This is a discussion on Bacterial brown spot on Colmonara within the Orchid Ailments / The Compost Pile forums, part of the Orchid Culture category; It appears that I have a case of bacterial brown spot on my Colmonara Massai ...

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  1. #1
    hcubed's Avatar
    hcubed is offline Senior Member
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    Default Bacterial brown spot on Colmonara

    It appears that I have a case of bacterial brown spot on my Colmonara Massai Splash. I can post pics later, but that looks about right according to my books.

    What do you folks do to treat this? I am looking for household remedies if possible, particularly ones not dependent on a particular product/brand name since I probably won't be able to find that without a fair amount of trouble here. (no idea where I would get Murphy's Oil Soap for example, but maybe someone knows what the important characteristics of that remedy are?).

    So far I have mixed a spray of water and baking soda and have been cutting off infected parts, though the cutting is really only making the plant look sad and the spots come back farther down the leaf. Aside from chopped leaves though, the plant doesn't appear to be suffering much.

    Also, just how contagious is this? High levels of quarantine needed? And where does it most likely come from?

    Thanks for all your help!

  2. #2
    Brutal_Dreamer's Avatar
    Brutal_Dreamer is offline Dreaming with my eyes open...
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    This is a hard one to answer. Maybe one of our chemist-minded folks can help. I would also request a photo of the bacterial brown spots on your orchid. This might help someone in the future with the same problem. It also could get you an answer from someone who knows how to treat the problem, but calls it something different.

    Cheers,
    BD

  3. #3
    Ron-NY is offline rothaholic
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    If it is bacterial you will want to cut the leaf back to clean tissue, you can dust the cut with powdered cinnamon. Bacterial rot is moist and smelly. You might be seeing leaf-spotting from fungi. Many fungi infect orchid leaves, but unlike the pathogens above, they are not usually lethal. Most growers, and their orchids, just live with them.

    Symptoms: The fungi involved, Cercospora species for the most part, cause varying degrees of brown to black spotting on the leaves (and sometimes the pseudobulbs).

    Fungicides are available that can be sprayed onto orchids regularly. Making sure the plant has adequate ventilation, and is being grown under optimum conditions, helps reduce leaf-spotting. Reduce misting the leaves with water.

    Baking soda mixed with horticultural oil could possibly work, I have heard.Also cinnamon has a naturally
    occurring fungicide.
    Last edited by Ron-NY; May 26th, 2009 at 01:42 PM.

  4. #4
    hcubed's Avatar
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    Here are the pics! Didn't have time this morning before work. :-)

    It is hard to photograph well, but I hope it helps. It doesn't look like all that much right now because parts have been cut off already, but it keeps spreading so I would like to figure out what to do before it gets too bad....at least none of the other plants have it.

    I had also thought about sun damage, but it seems unlikely to me. What do you all think then?




  5. #5
    Brutal_Dreamer's Avatar
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    I would spray with a fungicide. It looks like the leaf (in the first photo anyway) was wet too long. The spots in the second photo look entirely different to me - maybe a pest or sun-burn.

    Cheers,
    BD

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