Virus or fungus ?

[ronalt]

Hi,

I've got this bulbophyllum lobbii. The old leaf has brown spots but the new leaves are clean. Could you tell what it is ? and what to do ?

Many thanks !

[ronalt]

Originally Posted by Dorothy

How about giving us a little info on your growing conditions .. That would help shed some light on the problem
BTW .. I love this little bulbo
( I have yet to acquire one though )

Well, I live in a flat (no greenhouse), right now I have pretty good conditions, around 50% relative humidity and 21°C and good light. This bulbo is cultivated in a mix of bark and sphagnum.

Last year I've bought quite a lot of plants from different places, some of which were pretty unhealthy. I fear a few could be infected with a virus but it is difficult to check. At the beginning of the winter I had a big problem with fungus (caused by high humidity with insufficient ventilation and heating). Now part of my plants have consequences of the fungus attack and it is event harder to decide if their aspect is related to a virus or to fungus. I also have suspicious cattleya leaves that I'll post later. Many thanks if you can help me.

[orchid-eric]

Could it be tobacco mosaic ? Thats my only guess be the way it looks. Good luck !

Eric

[ronalt]

Originally Posted by orchid-eric

Could it be tobacco mosaic ? Thats my only guess be the way it looks. Good luck !

Eric

That is what I fear... Is there a way to know for sure ?
If the new leaves get the same problem I think I'll throw out the plant but if they stay clean can I say that it is not a virus ?

[mojomick]

You could send a leaf to Critter Creek Labs and for a nominal fee they could find out if indeed it is a virus. In the meantime, I might keep it isolated from the rest of my collection. I also am concerned about your comment of getting unhealthy plants. Do you isolate your new plants for 2 to 3 weeks before adding to your collection? If not, it might be a good idea. If I have an unhealthy arrival, it doesn't get into the greenhouse until it is healthy or I send it back to the vendor. The leaf picture does look like a lot like a virus pictured in the books. Betty

[ronalt]

Originally Posted by mojomick

You could send a leaf to Critter Creek Labs and for a nominal fee they could find out if indeed it is a virus. In the meantime, I might keep it isolated from the rest of my collection. I also am concerned about your comment of getting unhealthy plants. Do you isolate your new plants for 2 to 3 weeks before adding to your collection? If not, it might be a good idea. If I have an unhealthy arrival, it doesn't get into the greenhouse until it is healthy or I send it back to the vendor. The leaf picture does look like a lot like a virus pictured in the books. Betty

Thanks for your answer Betty,

The test for virus certainly costs as much as the plant itself... I've isolated the plant along with other suspicious ones. I need to know if I can draw a conclusion about them by inspecting the development of the new leaves..I found very few information about that, maybe because most people don't even wait for new leaves to destroy the plant in that case.

You're right it is safer to isolate new plants for a few weeks after receiving them. Before having these various problems I was not so aware of orchid diseases, from now on I will do it for sure.

[BikerDoc5968]

How long have you had the plant and do you/others smoke? Tobacco mosaic is certainly possible. I wonder could this be sunburn?

[camille1585]

I agree with what's been said. From the looks of it, it's a textbook example of ringspot virus symptoms, probably odontoglossum ringspot virus (ORV) which is a very common virus in orchids. ORV is sometimes called the orchid strain of Tobacco Mosaic Virus, mentioned by Eric.

The problem is that viruses are so hard to diagnose. Plants can be clean but infected, and plants that look virused are actually virus free... I saw nice examples of this in my plant virology class in the last few weeks.

If this is a plant you care about you could also order an orchid virus test kit. These kits test for the 2 or 3 main orchid viruses. It's not that cheap(£8,50 per test) but may be worth it.
Orchid Virus Tests
Agdia in the USA also sells packs of 5 tests for $32

[mojomick]

Critter Creek only charges $5.00 for a leaf to be evaluated. If the plant is a cheap one I guess it's not worth it. But if your plant is one you treasure, or is expensive, then it doesn't seem like all that much to make sure you are not infecting your entire collection. I just sent them 5 leaves, just cause I was not really sure of what was happening. This doesn't really look like sunburn to me. Check out tobacco mosaic on the web and you might be able to find a picture. It looks a lot like those I've seen. Betty