Hop latent viroid (HLVd) remains one of the most studied infectious agents in cannabis production, and current research continues to broaden the diagnostic and breeding options available to licensed producers. New work being presented at CannMed 26 this April highlights a tolerance-based approach: rather than relying solely on testing and removal, researchers are characterising cultivars whose biology limits the impact of infection.
The Jamaican Lion Lead
The CannMed 26 talk by Ansley Burtch describes a genomic and transcriptomic analysis of the Jamaican Lion cultivar. Published findings indicate the viroid is largely localised in the roots of this cultivar, with reduced movement to floral tissues. The session abstract is here: Decoding Natural Hop Latent Viroid Tolerance. Early findings point to activation of root metabolism genes and the anthocyanin and betalain biosynthesis pathways during infection, consistent with a tolerance-type response rather than exclusion-type resistance.
The distinction matters for breeding. Exclusion (resistance) keeps the viroid out. Tolerance lets the viroid in but limits the symptom cascade. The medium-term research goal described by the authors is to identify markers that breeders can select for, alongside cannabinoid profile, terpene profile, and other commercial traits.
Why This Adds to the Toolkit
HLVd has been under active research for nearly a decade. The 2025 review in Plants by Punja and colleagues summarises the current understanding of transmission, longevity, and management practices: Transmission, Spread, Longevity and Management of Hop Latent Viroid. A separate Canadian study from the University of Guelph and McGill characterised prevalence and symptomology in greenhouse-grown cannabis here in Canada: Symptomology, prevalence, and impact of HLVd on greenhouse-grown cannabis in Canada.
The current best-practice framework combines three elements: routine diagnostic testing of mother plants and incoming material, disciplined sanitation, and (as research advances) cultivar-level decisions informed by tolerance work. Tolerance research adds an additional lever rather than replacing the others.
What Tolerance Does Not Mean
Tolerance is not immunity. A tolerant plant still carries the viroid and can shed it through cuttings and pruning surfaces. Two implications matter for licensed producers right now:
- Routine HLVd testing on mother plants and incoming clones remains essential. Tolerant cultivars, when they reach commercial channels, will benefit from the same diagnostic regime to confirm status and rule out co-infection.
- Sanitation practices (tool sterilization, glove changes between plants, disposable scalpels for tissue work) continue to support every cultivation programme.
Diagnostic Workflow Programmes Use in 2026
The current standard of care for licensed cannabis producers in Canada involves testing mother plants on a routine cadence, testing incoming clones before propagation, and confirming any symptomatic plant in flower within a single shift. Agdia’s AmplifyRP XRT platform has become a leading format for this work because it gives nucleic-acid-level specificity in under an hour without requiring a thermocycler. The HLVd AmplifyRP XRT is paired with the XRT positive control for in-house verification, and the workflow is approachable enough that scouts can run it themselves after a short training session.
Key practical features of the AmplifyRP XRT format that producers consistently cite:
- Single-temperature isothermal reaction, no thermocycler required.
- Validated for use on raw plant tissue with a simple sample preparation step.
- Result available in under an hour, supporting same-shift decisions.
- Visual readout on a lateral flow device, no specialised reader required.
Producers who want a deeper read on the diagnostic landscape will find the 2024 detection and infectivity paper useful: New Insights into Hop Latent Viroid Detection, Infectivity, Host Range, and Transmission.
Practical Reads for Cultivation and Breeding Teams
Three things are worth doing with this week’s CannMed news. First, treat the tolerance work as an emerging tool that complements existing diagnostic and sanitation practices. Second, audit your current testing cadence to make sure mother plants, clones, and any symptomatic flower are covered. Third, watch for marker work that emerges from the Jamaican Lion analysis, because tolerance markers entering selection programmes within the next few seasons will start to influence cultivar choice.
For breeding-side groups, the U.S. Department of Agriculture’s NIFA-CARE collaboration is the most active publicly funded effort on HLVd research priorities, including transmission by insect vectors, pollen, and seed: Biology and Management of Hop Latent Viroid (NIFA-CARE project page).
Practical Notes for In-House Labs
For licensed producers running their HLVd programmes in-house, the AmplifyRP XRT for HLVd has been validated on raw cannabis tissue with a simple sample preparation step. The reaction runs at a single isothermal temperature, returns a result in under an hour, and reads out visually on a lateral flow device. Producers using the XRT positive control on every batch generate the QA documentation that supports internal traceability and audits. These attributes (validated sample matrix, single-temperature workflow, visual readout, batch-level positive control) are the core reasons the format has been adopted by Canadian licensed producers as a routine option for mother room and clone-screening cadences.
Bottom Line
HLVd management in 2026 still combines routine diagnostic testing with disciplined sanitation, and the research direction is expanding to include tolerance-based cultivar selection. Producers who keep their HLVd diagnostic programmes tight will be in the best position to evaluate tolerant cultivars on their merits when they enter commercial channels.
Need to support an HLVd testing protocol with validated, ready-to-use kits? Browse the AmplifyRP XRT lineup at Immunomart. We supply licensed producers across Canada with same-day Vancouver dispatch.
