Black Spots on leaves, please help!
 

Hello,

I am relatively new to orchid growing, and have been growing for about a year. Two weeks ago a noticed a horrible black spot on my cattleya, that grew bigger daily, I cut the leaf, after a few days, I noticed it was in the base if the plant and I decided to destroy the plant. Since then I have found black spots, not exactly the same as that which was on my cattleya, but black spots none the less on several... Actually nearly all of my plants. I have trimmed back the affected leaves and treated them with a cinnamon paste, and I have also treated the plants with physalis 20. It seems to have worked or stopped the progression in my habenaria and lady Isabel. But to treat some of the others I would have to cut all of their leaves off, is that necessary? I am including pictures of my bulbophyllum doggy doo, miltonia, and paph moon stone leaves. I'm hoping for some advise other than destroying the plants.

Thank you,

Sara

Here's the paph.

Here's the bulbo.

I would suspect bug bites. They eclipse into fungi and/or viruses so check your medium for buglets, check for tiny webs between and around plants. If that's the case, I'd give them a systemic insecticide like Bayers 3-in-1 for Roses. Actually...I'd do it anyway. I hope this helps.

Hi Janet. I never thought it might be bugs, but I will treat them for that as well. Thank you for the tip!

Their leaf tips are turning brown in some cases as well, would bugs cause this?

Sara

St. Augustine Orchid Society - North Florida Orchid Growing. Go there and look for your problem.

Thanks James. It looks a little like bacterial brown spot to me. So treatment with by cutting the leaves, cinnamon and physan should work if it has not gotten to the center of the plant..... it has just moved so quickly between my plants! I have placed a fan in the room with them and reduced the temp in my house. I don't know if that is going to help or not.

Once you've decided what the problem is, and if it turns out to be an insect pest, or even a fungal or bacterial infection, then Neem Oil might be a first line choice of treatment and prevention. Neem Oil is said to be effective against several different insects as well as some fungal and bacterial infections.

Organic Fungicide Bactericide Neem Oil

AOS Neem Oil

I would, as soon as possible, get some systemic fungicide as well as a topical fungicide and use them together.