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Algae on leaves

Discussion in 'Issues, Disease and Pests' started by Uluwehi, Jan 19, 2011.

  1. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I haven't used it for watering or as a preventative. I use it if I want to clean the leaves of a plant or plants or if I have a fungus or some kind of crude that frequently grows on certain of the mounting woods I use. I also use it when i have a new growth that damps off.

    I did just go out and check the nigro-hirsute dendrobium I sprayed a while back. The leaves didn't seem to like it. They are a bit mottled and yellow. A good reason to not do the whole collection.
     
  2. mrbreeze

    mrbreeze Anglican Supporting Member

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    "how often do you spray with the full 3% concentration?"

    I often spray after I soak my mounts during the warm season. And then occasionally for no particular reason. And if I notice something that looks suspicious I will spray it, including on orchids. My mental research over the past few minutes has indicated that an approach somewhere between random and periodic should work for many situations. Of course everyone's conditions are different so it is hard to generalize.

    And for god's sake don't put me on speed dial. I hate phones and squirrels and mosquitoes with almost equal vigor.
     
  3. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    Besides the fact that I am crushed that MrB doesn't want to be on speed dial, I should mention that the concentrations of H2O2 above 3% are not for live plants but for sterilization of tools in the lab or of seed.
     
  4. Reyna

    Reyna Orchid Obsessed Supporting Member

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    This is a fascinating post. I have used a dilluted solution of Physan, and hadn't ever heard of using H2O2. That is a great idea. :) Thanks!
     
  5. Uluwehi

    Uluwehi angraecoids, dendrobiums and more Supporting Member

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    Only two months after committing my first H2O2 assisted algaecide, I found that I needed to repeat the treatment. Of course the algae wasn't as bad, but I didn't want to wait for as much build-up this time 'round.

    Two weeks ago I sprayed all the plants in my indoor chamber, however this time I forgot to do a water rinse after spraying the H202. While it didn't kill anything, there was some damage. Virtually all active root tips were disappeared overnight and a handful of angraecoid species got some cell damage in places where the H202 pooled on sensitive foliage. Angraecum dendrobiopsis was particularly affected. I'll get some pictures to show what it looked like.

    So the moral of the story is, H202 can be very helpful, just don't let the H202 dry on the plants without having rinsed it off with plenty of clean water beforehand.
     
  6. orchidkarma

    orchidkarma Member

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    Interesting report Jacob, thank you. I have just heard of commercial growers here in Europe using a diluted mix of 3% H2O2 as a fungicide. They recommend 1 liter to 300 liters of water (so about 3ml per liter). I think I am going to test that.
     
  7. Uluwehi

    Uluwehi angraecoids, dendrobiums and more Supporting Member

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    Just thought I'd add to my original post. I'm finding that I get less algal growth on leaves if I can get them to dry off faster after watering via increased air circulation.

    I always wash the H202 off right away after I've removed the algae. Using a paint brush is a great way to get the algae off of tender angraecoids after allowing the H202 to fizzle for about 30-60 seconds.
     
  8. MiKa

    MiKa Active Member Supporting Member

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    Very interesting thread. I have been thinking a long time on trying to add UV-light in the greenhouse. Since the glass blocks the UV rays off.
    I know that the plants dont use the UV for photosynthesis, but in nature the plants are exposed to UV on a daily basis. Not only does the UV kill algae, I belive UV plays other roles that are not known.
    I'm planning on experimenting with this in the near future.
    Any thoughts? (I belive I will start a new thread on this)
     
  9. Uluwehi

    Uluwehi angraecoids, dendrobiums and more Supporting Member

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    Very intriguing! I'll be quite interested to see what you learn from your experimentation with supplemental UV light.
     
  10. DPfarr

    DPfarr Well-Known Member

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    The only detriment I've run into with H2O2 is with my terrarium Lepanthes and related soft leaved species. I cant be 100% certain it was the cause of the burn but I havent tried it since.

    H202 also helps with root growth and bifurcation.
     
  11. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    A friend was helping me groom plants getting ready for POE this spring. She was cleaning up algae with 3% H2O2. I noticed later that my specimen of Trichocentrum longicalcaratum no longer had algae, but it also no longer had any red color in the flowers. The flowers were fine, but the blood red was not brown. I've used it on things such as L calodictyon and L saltatrix without problems. I don't know if it makes a difference, but I don't use it in warm conditions.
     
  12. Uluwehi

    Uluwehi angraecoids, dendrobiums and more Supporting Member

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    If not washed off, H202 will defoliate some thin-leaved Dendrobium species. In my experience D. trichostomum and the nigrohirsute group are especially tender.