Black patch on Phal leaf. Is this disease?

[lilylove12]

Fairly new to growing orchids. I have a phal that was growing long leaves during the late summer. A few months ago I noticed some dark patches and spots on the leaf which I assumed to be sunburned so I moved it to lower light. (Growing it inside my home near window with shades). About a month ago I noticed a new set of dark patches. I assumed again sunburn so I moved it into even lower light. Today I noticed the patches seem more prominent especially on the bottom of the leaf. Not sure if it was there before but I didn’t see it. They don’t seem to be spreading super fast. However the leaves appear almost translucent. Is this rot or other disease? Should I cut off this portion of the leaf?

[aliceinwl]

Is the dark area mushy feeling? I don’t have a lot of experience, but it looks like some type of infection to me. I had something similar get started on one of my Phal leaves this fall. It kind of felt like a water balloon. I cut off the infected portion about a centimeter down from the rot.

In your case, I’d wait for a second opinion before you cut and if you are advised to cut, sterilize the blade between leaves. I’d also thoroughly wash my hands after touching the plant, especially the area with the lesion to avoid spreading it (if it is an infection).

[lilylove12]

Thanks aliceinwl. I will wait for second opinion. It doesn’t seem to be spreading very fast right now so hopefully it won’t take too long for others to respond. Did your orchid produce a spike after you cut the leaf? I was very hopeful with this orchid since it seemed to be thriving not too long ago.

[Dollythehun]

I agree with Alice, it doesn't look like sunburn to me. I'd wait for a truly expert opinion before you cut and dust. I'd also order some Inocucor from First Rays, just to have on hand. It's expensive but I recently saved a phal equestris using it.

So to recap: wait for another opinion and visit First Rays website.

[Ray]

That is definitely an infection and not sunburn.

Your options include throwing it away and replacing it, treating with a copper-based product like Phyton-27, or use of an organic treatment like Concentric Ag Garden Solution.

[Dollythehun]

And where would the OP find that, Ray?

[Orchid Whisperer]

That looks like a bacterial infection.

Take a sharp blade (single-edge razor blade, X-acto type knife, or other very sharp blade) cut off the leaf at least an inch into healthy green leaf tissue (healthy = no yellowing, Browning, blackening, or softening).

Keep the plant dry, no water, observe for at least a week. If no other leaves are affected, you can water again, carefully, just the roots.

I don't usually use peroxide or alcohol on my plants, but after the waiting period, you can take a paper towel, lightly damp with rubbing alcohol (or hydrogen peroxide) and wipe the surfaces of the mature leaves in case spores or bacteria have spread to other leaves. Proceed from younger unaffected leaves (maybe avoid really tender ones that are still growing), as the paper towel becomes soiled switch to a new paper towel and move down toward older leaves, end with what remains of the cut leaves.

[lilylove12]

Thanks Ray and Orchid Whisperer. I just cut off the portion this morning. Broke my heart. I’ll try giving it a waiting period. Should I expect it to spike this season after the cutting?

[Orchid Whisperer]

Re: spiking, hard to tell from 2 leaves. If most of the plant is in good shape, and your growing conditions are good (proper light, etc.), it could still make a spike.

BTW, depending on your water supply, adding calcium to your plant's fertilizer regimen may help ward off disease. Places like Florida, Great Lakes area, Great Plains often have enough calcium (and magnesium and sulfur, which are also helpful). I live in Northeast Georgia, much of our water is deficient in CA and Mg, so I mix a tablespoon each of gypsum (or Plaster of Paris) and Epsom salts in a gallon of water, let it stand overnight to dissolve. When you water, add a cup of that solution to your regular water. It won't really help the existing leaves, but it will strengthen new leaves.