Positive agitest virus strip.
 

Hello all,

I am quite sad as one of my plants has tested positive for a virus. It tested positive for CymMV. It is a Phal violecea that I got from a local and trustworthy grower. He imported it from a nursery in Taiwan.

I have attached a picture of the plant.

Could it be a false positive? I tested it twice and got the same result. Strangely, the CymMV line turned red immediately and slightly before the control line. That said, the control line is very clearly there. Would the fact that I also ran out of the bags and droppers that came with the kit so I am using my own (new in box) influence the results?

On my first test I used a 1cm square. On the 2nd test I used a .5cm sample.

The plant looks awful. It's likely a true positive test.

Just tested another orchid (using different clippers of course) and got a negative test using the exact same method. Pretty sure now that means it is a positive test. Is using Lysol and Comet (powdered bleach) enough to disinfect the area?

I am pretty sad about this one. I am still going to keep the plant because I never throw away living plants. That said, it is banished from the greenhouse. It will have to live a life of solitude. :(

it is such a shame because it just recently bloomed with such nice flowers.

Is it likely it infected others? I never used any cutting tools on this one before but it was rather close to many other plants.

No, it is not likely it infected others unless sucking insects were in the greenhouse.

Such viruses are spread by vascular fluids.

Virused plants, as we have discussed in another thread, may not be a lost cause at all. I’ve read some opinions that all phalaenopsis are virused. Personally, I don’t know that to be true or false, but it really isn’t that unreasonable. I suspect you need to give that plant better care, causing it less cultural stress, which is probably what brought out the symptoms so strongly.

No question of that being a positive test... that line is very strong. Occasionally there will be a "barely there" line that could indicate a false positive though could also be due to sample not having enough virus for a strong test. (In those cases retest in a few months) But that one is unambiguous... keep separate from the other orchids, maintain good hygiene, and it's unlikely to infect anything else.

I did have a two spot spider mite problem over the summer.

False positives are incredibly rare (for all intents and purposes, it doesn't happen). I would clean up the surrounding area and spray heavily with Physan 20, a bleach-based cleaner, or whatever you prefer. I would also wait 2-3 months and retest the plants that sit next to it to be thorough.

If you never share tools between them, water never splashes, and the leaves don't brush past each other often, then it probably wouldn't spread. If you water by sprinklers overhead or a hose, or bottom water with a common basin, or if you use the same pair of shears between multiple plants, etc., then you should probably do further testing.

Spider mites have a small chance to infect other plants. If the infections continue periodically, then the small chance probably increases. I'm not sure about CymMV, but for example false (flat) mites are the primary vector of orchid fleck virus (OFV). Since you're keeping the plant around, maybe you'll have to be more proactive on the insecticides.

I never shared unsterile tools between plants. I usually torch any tools I use. I do have splashing water in the GH as I water with a hose. I do use saucers but they tend to overflow. I don’t think I ever got water from this plant on others though. It was a Taiwanese import. It did not seem ill when I first got it but who knows. It has been progressively getting more chlorotic for months.

I am not going to keep this one in the GH anymore though. It will stay in a bathroom somewhere in my house probably. I never throw away living plants but I’ll eventually get a 2nd one for the greenhouse.