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Bacterial brown spot

Discussion in 'Issues, Disease and Pests' started by orchidkarma, Jan 20, 2012.

  1. orchidkarma

    orchidkarma Member

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    I desperately need some advice on how to combat an outbreak of (what looks to be) bacterial brown spot in my cool vivarium (see photos). I have treated repeatedly with Physan 20, and it has halted the outbreak, but not completely solved the problem, 3 months ongoing now. I still see leaves here and there turning... I have lost about 10 plants or so (out of 300+), and many have been severely reduced in size because of leaves turning yellow and falling off, or me removing affected leaves to help stop the contamination. I really need some help how to take care of this once and for all! :bang:

    It started a few months ago when the fans in the viv had been turned off for a couple of days by mistake. Soon after this I notice the first symptoms... yellow leaves, brown sunken wet spots, and it was spreading pretty fast. I isolated those plants and cut off all the affected leaves with sterile tools. We do not have Physan 20 in Sweden, but I had a friend help me out and send me some. By the time it arrived I had seen symptoms on various plants all over the viv, since I water by misting system it was spreading all over, so no use quarantining plants.

    When the Physan arrived I took all the mounts and all the pots out of the viv (about 300 plants), removed all affected leaves, soaked them mounts/pots and all for 10 minutes in Physan (1 tbl/gallon, 1 gal = almost 4 liter) as recommended for treatment of Erwinia... figuring I wanted give it a good "cure" for starters. I also sprayed down the whole viv top to bottom (soaking the EpiWeb back wall) liberally with Physan. This seemed to halt the spreading markedly, but not completely. Killed off about 70% of all the moss though, but that's fine. Since then I have sprayed all plants and viv every 2 weeks with Physan (2 tsp/gallon as directed on the bottle).

    Physan is keeping things at bay somewhat, but is has not solved it! I still feel like it is a slooow loosing battle... what can I do?? Obviously I need to kill whatever pathogen this is, because otherwise everything is good, it is blooming like crazy! Are there better stuff (poisons, methods?) I can use - how do I fix this? HELP!!!!

    Vivarium measures 175 cm wide, 160 cm tall and 65 cm deep. EpiWeb walls with a Vivaria rain system. Temps 20-22 C day, 10-12 C night. RH 70-80 days, 80-90% nights. I have good air circulation in there and fresh air intake.

    afarm8.staticflickr.com_7007_6731055317_d40d79212d_b.jpg
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  2. Dale

    Dale New Member

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    Rotate your fungicides.
     
  3. Jon

    Jon Mmmm... bulbophyllum...

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    Let it dry out and sprinkle cinnamon all over the place. Physan can work well, but it can also damage plants. Be careful with it.
     
  4. Boytjie

    Boytjie Out hiking Supporting Member

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    Curious: would cinnamon also work in mist form? i.e., could you mix cinnamon powder in a spray bottle with water and apply it that way? (...Stupid question? I'll shut up now.)
     
  5. Uluwehi

    Uluwehi angraecoids, dendrobiums and more Supporting Member

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    How very frustrating! Have you used Chlorothalonil? Aside from chemicals, I think increased air circulation will go great lengths in helping prevent new infections.

    I've learnt more and more in my vivarium that increased air circulation really solves fungal and bacterial problems. In my vivarium it's often vexing to figure out where to place additional fans to make sure not one plant or group of plants is getting too much draft and to make sure the fan doesn't get wet and short-out. In my recent 50% depopulation of the vivarium I ended up experimenting with new fan positions. I now have a fan sitting at the base of one end of the vivarium angled diagonally upwards across the length of the space and it is making a huge difference. Leaves and roots are drying-off faster, roots are now reaching more for their mounts instead of growing into "outer space" and I don't have nearly as much algal build-up.
     
  6. Tom-DE

    Tom-DE Well-Known Member Supporting Member

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    I agree more air movement. Not sure this will be for everyone, but I use dehumidifier from time to time...

    Jacob, not sure what it is in my case, many of my Dendrobium have their roots grown out into the "outer space" but not so much with othere genera. What is the story of your 50% depopulation of the vivarium?
     
  7. Uluwehi

    Uluwehi angraecoids, dendrobiums and more Supporting Member

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    It's interesting to hear that you use a dehumifider from time to time!

    Actually I don't mind roots growing into space, however I have a number of angraecoids who have been so content to grow roots anywhere but on their mounts that they have no way of holding on (e.g. AĆ«rangis, Plectrelminthus, etc.).

    Oh the story isn't sad or anything, it's just a combination of the fact that I ended up building a greenhouse outdoors, and didn't want to spend so much on electricity each month, so I turned off one of my 400w lamps and reduced the vivarium's orchids by 50%, moving the hardier, larger more intermediate growers out to the new structure outdoors. Hence "depopulation" :) Don't get me wrong, I love vivarium growing, I just don't like using so much electricity (green reasons) and I don't really have money to burn!
     
  8. Ray

    Ray Orchid Iconoclast Supporting Member

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    Nope. You CAN make a cinnamon infusion, though:

    Put about a tablespoon (15 ml) of cinnamon powder into a pint (~500 ml) bottle of isopropyl rubbing alcohol. Let it stand for 24 hours, and filter out the sediment (Melitta filters work great).

    or

    Put 2x that much cinnamon in that volume of hot water, and let it stand for several days.

    In both cases you end up with a cinnamaldehyde solution, which is a pretty good contact fungicide.
     
  9. Tom-DE

    Tom-DE Well-Known Member Supporting Member

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    "It's interesting to hear that you use a dehumifider from time to time!"

    I have been using dehumidifier for years. My basement growing area has good natural humidity year round. Sometimes, it is a bit high, especially in the summer. Right now, my growing areas still have 70+% humidity, which it is unusual for this time of the year(a bit wet and warmer this winter). The cool and damp situation always gives my plants problems.

    "Actually I don't mind roots growing into space, however I have a number of angraecoids who have been so content to grow roots anywhere but on their mounts that they have no way of holding on (e.g. AĆ«rangis, Plectrelminthus, etc.)."

    Same here, but not as bad as some of my mounted Dendrobiums. I think some of the Angraecoids might grow like that naturally in the wild.

    "Oh the story isn't sad or anything, it's just a combination of the fact that I ended up building a greenhouse outdoors..."

    Good to hear that.
     
  10. orchidkarma

    orchidkarma Member

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    Thanks a lot for your answers!!! What about the diagnosis? ...am I right about thinking bacterial brown spot?? Bacterial, fungal?

    Jacob, no I have not used Chlorothalonil, we have such limited options here in Sweden... but since it is not systemic I think I need to look for one that is first? Today I have four 120cm 1850rpm fans running all the time, plus the cool air intake that runa intermittent when needed, and I can see leaves gently bobbing in the breeze all over the viv... However, just thought I would add to this discussion that where I see most problems are actually in the breezier sections...

    That said, I have purchased one more fan, but just have not figured out where to place it. I have been working on an idea to do like you have, Jacob, at the base of one end of the vivarium angled diagonally upwards across the length of the space. Just need to workout how to protect it from the water though... have an idea of using a cutoff pvc pipe...

    Thanks Dale, yes, I need to rotate my fungicides... trouble is, they are terribly hard to get here...

    Thanks a lot Ray for the cinnamon infusion recipe. I would love to use that for "every day" topical (rather than hard core poisons) after I have come to grips with this BIG problem... at this stage I want something more powerful.

    My concern is two really...

    1. I think I need to use something systemic.
    - I feel that many of the cool growers, mostly pleurothallids that I grow are sensitive to Physan 20... maybe it is even adding to the plant loss?? (Jon, I am with you there... need to be careful...)
    - Physan 20 does not "stick" for very long... and I have been going at it for a while now already...

    2. In choosing a systemic fungicide and bactericide (probably should treat both since I am unsure what I am battling)... what do you recommend using for sensitive pleurothallids etc?
    - What about Phyton-27?
    - or how about Cleary's 3336 WP?
    - Anything better??????

    Any tips where to get them in Europe?
     
  11. Uluwehi

    Uluwehi angraecoids, dendrobiums and more Supporting Member

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    Oh my :( I wish I could help more
     
  12. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Karma, I sent you a pm and an email (wasn't sure the pm was going through). Did you get them?
     
  13. orchidkarma

    orchidkarma Member

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    Got it!! Just wrote you back, thanks Marni!!
     
  14. dounoharm

    dounoharm almost there

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    phyton 27 may kill your problem, but it will wreak havoc on your dendobiums and some others....you can take everything out and wash down the whole system with it tho, and it will help.....i wash my gh down with it twice a year on general purposes.....gl
     
  15. orchidkarma

    orchidkarma Member

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    Thanks. I have come to the same conclusion about Physan 20 myself. I use it to clean the hard surfaces in the viv/growing room mm. Good for getting rid of algae and moss too. I have since gotten a handle on this, rebuilt the viv a while back, you can read about it here.