Did you ever wonder what an orchid virus did to your orchids? Well below are some photos of leaves from some orchids with virus. These may assist with recognising some of the symptoms orchid virus may cause. The most reliable symptom of virus is flower colour break (not shown).
There is no way to cure a virus. The orchid must be destroyed, preferably by burning, but wrapping in a strong plastic bag and sending to the dump is the normal method of disposal where burning is not permitted. DO NOT give the orchid away or dump the orchid without wrapping. This will only spread the virus.
Unfortunately, there is no reliable method to identify virused plants by looking at an Orchid. There are many extremely variable symptoms associated with a particular virus. These can be a useful guide to identify suspicious plants, but the only reliable method to identify virused plants is a laboratory test. These are available in most areas in Australia from Universities or the Department of Primary Industry. The cost per test varies, but is currently between $10 and $50 per plant. Your local orchid society or orchid nursery will be able to advise you of the best place to get your orchids tested.
In Brisbane, I used the University of Queensland who charged $11 ($10 plus $1 GST) per orchid for testing. Unfortunately, UQ has recently decided to discontinue this service.
I am advised that Newtown Research Laboratories does electron microscope virus testing for $16.50 for each sample. I have not tried them as yet personally, but their contact details are:-
Orchid Flec Virus
This Cymbidium has orchid flec virus. Note the symmetrical markings and the yellow rectangular spots with distinct edges. These are classic symptoms of this virus. Click on a photo for an enlarged view.
This Brassia Rex also has Orchid Flec Virus which shows quite different symptoms. This plant shows a strong necrotic ring pattern. Click on a photo for an enlarged view.
Odontoglossum Ring Spot Virus
This Cymbidium has Odontoglossum Ring Spot Virus. It is showing necrotic spots together with chlorosis (lack of chlorophyll causing yellowing). The new leaves also show chlorosis, a fairly reliable symptom of virus. (If new leaves are clean, this may indicate a fungus rather than a virus.) Click on a photo for an enlarged view.
This Den. Hilda Poxon has rhabdovirus. Note the necrotic spots on the leaves. The white residue on the leaves is fungicide and not a symptom of the virus.
In opposition to commonly believed folklore, the new leaves of this orchid were perfectly clean and showed no necrotic spots or any other symptom possibly indicating virus.
As I said before, there is no way to reliably visually identify a virus. Below is a Cattleya orchid suspected of having virus, but tested negative to virus. As you can see, this orchid shows the classic circular markings you would expect in a virused orchid. The cause of these marks is unknown, but a fungus is suspected.
I have noticed that virus symptoms tend to go right through the leaf, not just appear on one leaf surface. The symptoms below only appear clearly on the top surface of the leaf. This may be one factor to help distinguish virus from other marks on your orchids.
As I said before however, there is no know reliable method of visual identification of virus. Thus, when in doubt, get the orchid tested.
Author & Scans: Graham Corbin