May 2025 pest watch: orchid viruses

19 June 2025

Orchid viruses: what you should know

Viruses are a common issue in orchid crops, with Odontoglossum ringspot virus (ORSV) and Cymbidium mosaic virus (CymMV) the most widespread.

Symptoms

These viruses can cause a range of symptoms depending on the orchid species, including black streaks or spots, ring-shaped lesions, mosaic leaf patterns and abnormal flower development. Because these symptoms vary so much, they are often mistaken for fungal infections, mite damage, phytotoxicity (chemical burn) or nutrient issues.

Infection is incurable

Both CymMV and ORSV spread extremely easily. Even a light touch – brushing against an infected plant and then a healthy one – can transfer the virus. Infection can also occur through:

leaves rubbing against one another
contaminated tools, benches, gloves or clothing.

Once a plant is infected, there is no cure. The virus remains for life, making prevention critical.

Prevention

To reduce the risk of virus spread, growers should:

only purchase plants that have been virus-indexed and confirmed free of CymMV and ORSV
remove and destroy any plants showing symptoms
disinfect tools and surfaces regularly.

To disinfect tools and surfaces, a 10% bleach solution (made from household bleach with 5% sodium hypochlorite) is effective if you apply it for at least 10 seconds – as long as the tools are free from organic matter – the disinfectants won’t work if you haven’t cleaned off soil, sap or leaf debris first. This is a common weak link in otherwise good hygiene systems. Be aware that bleach can corrode metal over time. While quaternary ammonium-based disinfectants are sometimes used, they may not be completely effective.

Suspected infection? What next

If you’re concerned about possible virus infection, you can submit photos and leaf samples to Grow Help Australia. All production nurseries are eligible for six free virus tests until the end of 2025.

Nurseries certified under NIASA and BioSecure HACCP are already building virus vigilance into their everyday practices – from propagation hygiene to dispatch checks. These industry standards help reduce biosecurity risks and support consistent plant health outcomes.

For a quick on-farm check, Agdia immunostrip tests are also available – like a COVID rapid test, you can run the test and see results yourself.

Need support? Your local GIA extension officer can help review hygiene protocols, interpret symptoms or talk you through the testing process.

Contact your local extension officer:

QLD/Northern NSW: Barry Naylor barry.naylor@greenlifeindustry.com.au
NSW/Northern Vic: Colin Hunt colin.hunt@greenlifeindustry.com.au
Vic: Stuart Burns stuart.burns@greenlifeindustry.com.au
WA/NT: Steve Blyth steve.blyth@greenlifeindustry.com.au
TAS/SA: Celeste Cook celeste.cook@greenlifeindustry.com.au
National Biosecurity Manager, John McDonald john.mcdonald@greenlifeindustry.com.au