Hop Latent Viroid in cannabis – Molecular diagnostic

Pathogen infections are devastating. Especially when the symptoms do not emerge in the early stage. That is how Hop Latent Viroid (HLVd) infected cannabis cultivations in America, Canada, and other cannabis producer’s countries.

Hop Latent Viroid (HLVd) is recently identified as a plant-specific pathogenic RNA. It is presumed by many growers and industries to be the major cause of “dudding” during the explant growth or clone propagation. RNA virus type is easier to be translated after hijacking the host’s cells and rapidly replicate themselves in a short amount of time.

That’s why growers need to understand the nature of this plant disease by knowing the symptoms and steps to avoid its transmission.


Since there are various emerging types of pathogens affecting the cannabis industry, it is seemingly difficult to undergo a preliminary assessment to detect the causal agent involved, followed by selecting the most applicable pest management practices.

However, some facts that should be kept in mind is the understanding of the pathogen’s transmission process.

  • Damping-off caused by fusarium genus commonly spreads through plant’s media such as soil or water, then it can affecting the internal part of the plant and creating brown color particularly in stem
  • Root rot caused by water mould fungi spreads through the water stream and cause an obvious root necrotic which affect the nutrient uptake and creating wilt on leaves
  • Powdery mildew and bud rot caused by air-borne fungi spreads through the air and left powdery patches in localized tissue that cause leaves to turn brown and drop prematurely

But, it is different with virus and viroid disease. This pathogen spreads via infected mother plants or contaminated tools that are used in operation. Some clones/cultivars can be symptomatic when infected by this virus while some others only show symptoms under certain environmental conditions. Due to the report recorded, the most visible symptom related to horizontal plant growth, brittle stems and stunting. At an early stage, the symptoms will exhibit the alternating patterns of yellow and green (mosaic), curling and distortion colour of young leaves. After the generative phase occurred, flowers appear as small and malformed inflorescences. This is commonly called a “dud” plant.

Virus symptoms somewhat resemble nutrient deficiencies such as magnesium, iron, or nitrogen that cause yellowing leaves. In addition, other abiotic stresses also show color distortion and curling leaves. Therefore, sanitary management only can not guarantee the fitness of the stock (mother) plants.


Until the recent exploration, researchers still figure out the control agents and active ingredients for pesticides to prevent the development of the symptoms. Since the active compound is still unavailable, the approach to reduce the pathogen’s survival rates must be done. This action can be implemented through sanitary measures, such as removal and destruction of all plant materials and debris that could contain inoculum of pathogens. The hygiene of tools and equipment especially during pruning or handling also need to do in more strictest protocols.

The first action to prevent the inoculum introduction is also the essential part of all stages, which is molecular testing. This diagnostic method is aimed to ensure that the stock plant is pathogen-free. This step should be done prior to the vegetative cutting stage. This method is also followed by the clearance of contaminated substrate and avoid planting in fields with a prior disease outbreak.


MyFloraDNA understands that this pathogen can take up so many efforts, and sanitary measures alone can not give an optimum result. Thus, we have developed “Pest Resistance Analysis” qPCR assays that can be used to screen cannabis plants for the presence of this pathogen.

The DNA extracted from infected plant leaves will be used as a resource to detect the molecules. Part of the leaves that should be taken is the cotyledon. First leaves appeared after germination. The sensitivity of our advanced technology will help growers to receive accurate results within 3 days and take immediate action before growing the plants further.

This service has proven its efficiency to help growers reducing the transmission of inoculum and save more resources. We aimed to give a long sustainable benefit for our client by combining environmental handling and molecular tools.

We encourage every grower, breeder, and nursery to start planning their Cannabis business and reach MyFloraDNA to create a great collaboration along the process.