Hop latent viroid (HLVd) has become a major biosecurity concern in commercial cannabis because it can move through contaminated plant sap and the tools, hands and workflows that contact infected material. For operators, the practical question is not only how to test plants, but how to reduce the chance that routine work carries contamination from one plant, room or production stage to another.

Start with the transmission pathway

HLVd management is a systems problem. Pruning tools, scissors, propagation equipment, work surfaces and other items that contact plant sap can become part of a mechanical transmission pathway. A useful biosecurity program therefore combines plant-health testing with controlled movement of people and tools, cleaning, disinfection and documentation.

Cleaning and disinfection are not the same step. Visible soil, organic matter, resin and crop debris should be removed before a disinfectant is expected to perform. Product concentration, contact time, water quality, surface compatibility and application method also matter.

What the third-party qPCR evaluation tested

A third-party evaluation prepared by Nathan T. Johnson, Ph.D. examined PRO-OXINE® Horticulture against HLVd using qPCR. The study exposed HLVd-containing cannabis plant material to PRO-OXINE at 250, 500, 1,000 and 2,000 ppm for 10 minutes. A 20% bleach treatment was included as a benchmark, along with controls. Conditions were tested in triplicate and the experiment was repeated.

The report states that the 250 ppm treatment produced a 5-log reduction in detectable HLVd RNA after the 10-minute exposure, comparable to the bleach benchmark in that test. The broader tested concentration range also substantially reduced detectable HLVd RNA.

What that result means — and what it does not

This is useful evidence for facility biosecurity planning, but it should be interpreted correctly. qPCR measures detectable nucleic-acid signal; it is not the same thing as a direct infectivity assay in a commercial crop. The report itself identifies additional work that would be valuable, including testing on different materials, assessing residual activity and conducting field trials in commercial facilities.

The study also does not replace a product label or regulatory authorization. Operators must follow the current product label, SDS and applicable federal, provincial/state and facility requirements for their location and intended use. In Canada, pest-control claims and uses must comply with Health Canada requirements and the registered label where applicable.

How to build HLVd controls into daily operations

• Separate clean and dirty workflows. Avoid moving tools and materials backward from higher-risk areas into propagation or mother stock without a defined sanitation step.
• Assign tools by room or zone where practical. Reducing shared equipment reduces opportunities for cross-contamination.
• Clean before disinfecting. Remove plant sap, resin, debris and other soils so the disinfectant reaches the surface.
• Standardize concentration and contact time. Use verified measuring methods and document the procedure.
• Train the team. A written SOP only works if staff understand when the protocol applies and how to execute it consistently.
• Verify the process. ATP or microbial environmental monitoring can help confirm cleaning consistency, while plant testing remains essential for HLVd surveillance.

Where PRO-OXINE fits

PRO-OXINE Horticulture is one tool that may fit into a broader sanitation program. It should not be treated as a substitute for testing, workflow controls, tool segregation or removal of infected plant material. The strongest program layers these controls together.

View PRO-OXINE Horticulture or read The Cannabis Biosecurity Playbook for Growhaus's broader facility approach.

Technical note: Always verify the current label, SDS, concentration, contact time and permitted use for your jurisdiction before application. Study findings described above are specific to the test conditions and should not be generalized beyond them without supporting evidence.