interesting method to test for virus

[johnblagg]

found this in Taylors guides --- sickle pod {cassia occidentalis} when ruubbed with a orchid infected with CyMV and globe amaranth when rubbed with the leaf of a plant infected with ORSV will develop classic signs of viral infection.....might be helpfull to someone

[Izzie]

What source is this from?

[johnblagg]

Taylors guides ORCHIDS

[nancy]

There are a number of things that can be used as "indicator plants" to test for virus. In addition to cassia (Cassia occidentalis), some varieties of amaranth (Gomphrena globosa), and amaranthus (Chenopodium amaranticolor), as well as Devil's Trumpet/datura (Datura stramonium) will all show viral symptoms pretty quickly. I suspect that almost any plant could theoretically be used, but the above are fast-growing and will show the signs within two weeks.
I keep thinking that I will give some of these a try, but haven't yet. In any case, I would double check a positive result with CritterCreek or another testing method before tossing a really choice plant. In fact, I think I'd also double check a negative result if I were very suspicious of a plant that was worth a lot to me.
If anybody experiments with these, we would all like to hear the results, I'm sure.
Regards - Nancy

[RobS]

You definatly can't use any plant for that but there might be more then these. Some plants can simply be non hosts, resistant or symptomless. But indeed typically fast growing plants are used for this kind of testing.

Thanks for this will see if I can get some of these seeds.

[Izzie]

By "showing signs"- does that mean that the indicator plant has contracted the virus, and will also need to be destroyed?

[johnblagg]

i would say yes but most of these are annual plants I think.I know the globe amaranth and datura are.

[RobS]

Yes definatly they are indeed mostly fast growing annual plants and can only be used to test one orchid. After that they are infected with the virus to (if the orchid was infected).

[Izzie]

Well I just happen to have a lot of the Gomphrena in my garden...but I don't want to sacrifice them yet.

[RobS]

Save some seed and sow them in small pots if you think you have an infected plant. Keep the orchid in isolation untill the indicator is large enough (4 true leaves or so).