Black Rings on Dendrobium-Phalaenopsis Hybrid

[KristenJ]

Hi all,

I have a Dendrobium-Phalaenopsis hybrid that has been having weird problems off and on for almost 2 years. I've asked around on Orchid Board and at Orchid Shows and tried just about everything. First it had browning tips. The suggestion was fertilizer burn, so I started doing flushes and it seemed to be okay. Then I moved to a place with softened water. And it had weird spots at the tips of the leaves. The suggestions were bacteria/fungus, so I started treating with Physan 20. It went away during summer/fall, but started up again during this winter. (This is a very long story short.)

I described everything that has happened with this orchid at the last orchid show, and they suggested that I try giving it a winter rest. I did this, and all of the leaves on the oldest cane turned yellow. Then today, I noticed the weird black rings (shown in the picture).

Does anybody have any idea at all what this could be? I would appreciate any help with this one. Thank you!

[Leafmite]

I have softened water, too, which is the reason I have a bunch of containers outside right now to collect rain. Softened tap water really isn't at all good for plants.
I'm not really found of round markings as they make me think virus but, sometimes, they are caused by a fungus. Does the orchid grow vigorously or does it seem to be weak? Do the new canes grow as large as the older canes? Does it bloom as frequently as it did? Do the blooms have color-break?

[KristenJ]

A few months ago I started using filtered water and all of my plants (house plants, outdoor plants, orchids) have all just been doing a million times better. We weren't familiar with the water softening issues before moving here.

It will normally grow the first half of the new cane very quickly. But then it stops at about half the height of the old canes that were present when I bought it. It grows one cane per year. So I have 3 original (old) canes at full height and 2 canes at half that height. It has not re-spiked or bloomed since I bought it in bloom.

I was treating it with Physan 20 for brown spots on the leaf tips a few months ago. This worked for awhile but then the spots returned and the Physan has not worked. So then I tried the winter rest. Which after that is when the leaves turned yellow. After being yellow for a few days and not falling off, I noticed the rings.

[Leafmite]

I couldn't tell if that was an old leaf or just a trick of the camera's flash. Opps. Sometimes patterns do form on leaves when they are getting ready to fall off. That, in itself is not suspicious, at least to me. What does concern me is that the orchid isn't as vigorous as it was. Sometimes that means it might have a virus. However, since this has been happening since you bought it, it could also be that it needs more light, fertilizer, longer growing season, warmer temperatures, or that the roots are not happy. Some Dendrobiums sulk when they are re-potted, too.
If it is a phal-den, it would not really want a winter rest. It prefers year-round warmth, light and water.
As it isn't blooming, try giving it more light (slow introduction so as not to burn leaves) and see if that helps.
Good luck!

[KristenJ]

Thanks for all of your help! I will try more light and stop the winter rest.

[james mickelso]

Look up phalaenopsis ring spot virus. You'll see you pictures there along with a bunch of others.

[KristenJ]

I googled for "phalaenopsis ring spot virus". I saw one picture that was kind of similar but it was green/yellow rings on a green leaf. Nothing is an exact match, but some are similar. Could they appear different since mine is a hybrid? Do you think Physan 20 might help, or will I have to throw my orchid out?

[james mickelso]

Search that website again and click on "images of Phalaenopsis ring spot virus" and drop down to row 17. Exact match. There are no cures for virus'. Sorry.

[KristenJ]

I was worried that was the case. Thanks for your help.

[Orchid Whisperer]

I am not convinced it is virus. Yes, viruses can produce concentric rings, but so can fungi.

These rings seem to be on a yellowing leaf that is on its way out anyway. The black dots in the rings look like fungal bodies. Is it just on that one yellowing leaf? Not showing up on the green leaves? If so, I think it is fungal, but it is probably wise to keep it isolated and under observation for other signs of virus (such as color break in the flowers). You can always test the plant for virus if you think it is worth it.