What is wrong with my orchid? Orchid leaf is limp with large brown/black spots on a yellowish portion of leaf. Leaf is gradually turning brownish from green.
Odontoglossum Ringspot Virus (ORSV)
This Cymbidium has Odontoglossum Ringspot 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.) .
It is important to remember that there is no cure for an orchid infected with ORSV , even though efforts have been made to produce genetically engineered resistant plants. This is not easy to do, particularly when infected plants are asymptomatic. Because of that, one should always buy orchids from certified producers and avoid bringing plants with symptoms home. Special attention should be given to mother plants, which ought to be guaranteed virus-free.
If viruses are already present in the area, several measures need to be taken. Infected plants should be discarded and the suspicious ones should be isolated to prevent further dissemination of the viruses. Separating plants of different ages also helps prevent viral spread, since the older the plant is, the higher its chance of being infected. ORSV can be transmitted by handling during dividing, repotting, cutting or any other management practice.
There are some interesting You Tube videos on Orchid Viruses, for example: ‘How to test orchids for viruses’ and ‘Recognizing Orchid Virus Symptoms’.
The Southern Ontario Orchid Society could also be a useful source of information: https://www.soos.ca