Best Practice Testing….
I recently visited two local backyard growers to purchase Cymbidium orchid plants, and my experience turned into a valuable case study on virus testing. I’ll also share here what I consider best practices when using field test kits and explain why they are crucial.
First, please check out our quick guide on pests and viruses. And for a detailed explanation of Cymbidium orchid viruses, refer to these pages.
Be Careful When Buying from Backyard Hobbyists
When buying plants from unfamiliar local sources, I always bring field test kits. This precaution helps me avoid introducing a virus-infected plant into my collection. Although it can be costly at $10 per test for plants I might not buy, it’s worth every cent. Bringing home an infected plant can jeopardise your entire collection, leading to far greater expenses.
During my first visit, I encountered a grower selling a well-known primary hybrid, Cym. Rosefieldense, and a less common Cym. Peter Pan. Despite having these varieties, I wanted more for breeding purposes. Upon arrival, the plants appeared okay from a distance but had very yellow and patchy leaves up close, raising my suspicions. I could have left then and saved my test kits, but I decided to test both plants for the grower’s and my own peace of mind. Unfortunately, both tested positive for ORSV. The grower appreciated the information, and the knowledge of the test results. Obviously I didn’t buy the plants, but I’m concerned they might end up in someone else’s collection.
The second grower also had Cym. Rosefieldense and what I believed was Cym. insigne. Unfortunately, I didn’t have enough test kits with me this time. The Cym. insigne tested positive for ORSV. Despite this, I purchased two Cym. Rosefieldense plants—one tested negative, and the other, untested, was nearby. Both were separated from the main group, so I hoped the second plant might be healthy.
Best Practices for Virus Testing
Lately, I’ve received numerous inquiries about virus testing for Cymbidium orchid plants, and seen many posts on Facebook on the subject. Most questions revolve around whether to test and why. The answer is clear: Yes, you must test, and do so thoroughly.
Here’s why:
After bringing home the two Cym. Rosefieldense plants, I washed them thoroughly. The next day, the untested plant started showing slight patchiness on its leaves, raising my concerns. I tested a leaf from one bulb, and it came back clean, but I wasn’t convinced. I tested leaves from each bulb, and to my dismay, every other bulb tested positive for ORSV. Only one clean bulb was among seven infected ones. So does this mean we can just split the plant up and keep the healthy bulb? Sadly, no……
Since all bulbs are connected by the rhizome, the virus will likely spread to the ‘clean’ bulb, if it hasn’t already. Even if it tests negative now. It probably won’t in 3-6 months.
My Testing Recommendations
I recommend taking a sample leaf from each bulb if possible. Perform a batch test with four, five, or even six small leaf samples (each from a different bulb) in the test kit at once. It might seem like a lot, but there’s plenty of room once it’s all mashed down. This method ensures thorough coverage and a complete picture of the plant’s health. And it will prevent you from buying a sick plant.
Why Test Seemingly Healthy Plants?
A well-grown, seemingly healthy Cymbidium orchid plant will not show virus symptoms until the virus has seriously taken hold. By then, it could have transmitted the virus to other plants. The only way ORSV or CymMV might appear in a healthy plant is if it’s stressed, causing the virus to manifest in the leaves.
Therefore, testing seemingly healthy plants is crucial to protect your collection and others. It’s also vital to test as much of the plant as possible.
My stance is that if part of the plant is infected, the whole plant is compromised. It’s a sad reality, but it’s the safest approach.
My unusual lack of thoroughness serves as a valuable virus lesson for all orchid enthusiasts!
The Agitest Orchid Virus 2-in-1 Rapid Test (CymMV + ORSV) kits are available in Australia from Barrita Orchids.
Images in this article were supplied by Nado Lenkic & Joshua White.