Beallara "Tahoma Glacier" with brown spots on leaves

[Gregor]

The hybrid described in title is affected by a desease showed in the below posted pictures. The problem has started like a small circular brown spots on leaves. These brown spots have progressed increasing in size along the days. At the edge of these spots sometimes occurs a watery and transparent aspect especially when the spots are observed on the leaf underside.
I have treated the plant with copper oxychloride with the intent to slow down the disease progress.
Somebody can explain me the best way to deal with this problem and the disease cause? Thank you in advance

[twostride]

I just had a very similar problem with an oncidium of mine. Other members suggested simply cutting the affected leaves off (one inch into the healthy tissue). I did this and treated the cuts with cinnamon. 2 weeks later and there is no indication of continued infection, and my orchid is spiking nicely. Good luck!

[Gregor]

Thank you twostride for your advice. I wanna ask you if you think the disease caused by bacterial agent, fungi or viral?

[twostride]

Oh goodness. That's out of my league, but after a lot of internet research during my own situation, it seems like it is fungal.

[spetrizio]

does not look like virus, so fungal or bacterial.
I think fungal is much easier to fix. treat with some fungicide anyhow. In Italy I think you can find Previcur energy from Bayer.

Bacteria could be succesfully treated only with antibiotics but I think it is forbidden to use on plants. For Bacterial brown spot antibiotics are tetracycline, streptomycin+tetracycline but I suppose you will not do that.
For smaller infections treatment is to cut infected areas, treat them with 10% bleach solution or Physan 20(probably you will not find Physan20 in Europe) or copper based fungicide ( like Champion WG 50 or Nordox WG 75 or something simmilar). Be carefull with copper fungicide. do not treat dendrobiums and blooming plants.
Also treat with 10% bleach solution or Physan surronding plants. move infected plants far away from other plants.


some links:
Orchid Diseases

http://www.icogo.org/images/Dr._Huan...se_Control.pdf

[Gregor]

Thanks spetrizio, I have cut the affected leaves and, in addition, as previously said, i have treated the entire plants with a copper based product. Can you explain me the effects of copper fungicide on blooming orhids?