HLVd is difficult to detect, making molecular testing essential in preventing considerable financial losses for growers. Don't allow HLVd to catch you off-guard – consider partnering with a trustworthy laboratory to preemptively combat this


Below are the key take-aways about HLVd and the implications to consider applicable to your operation

  1. The "duds" disease, caused by the hop latent viroid (HLVd), has emerged as a significant threat to the cannabis industry in North America since its first detection in 2019 [4]
  2. HLVd infection can cause a 50%-70% reduction in the tetrahydrocannabinol (THC) content of the crops, significantly diminishing their commercial value [3]
  3. HLVd is one of the smallest known infectious agents, and despite not showing characteristic symptoms, induces physiological changes in plants that affect the metabolites involved in terpene production, with linalol, myrcene, α and β-pinene reduction ranging from 13 to 41% [5]
  4. Symptoms include stunted growth, smaller leaves, malformations, and reduced flower mass, resulting in up to a 50% reduction in cannabinoid and terpene production. [6]
  5. As of 2021, 90% of all cannabis-growing facilities in California tested positive for HLVd  [7]
  6. Primary method of control is by using uninfected materials [8]
  7. The best detection method is through qPCR testing of the plant's genetic material [9] 
  8. Remember the VITAL signs and symptoms of the HLVd 

Don't allow HLVd to catch you off-guard – consider partnering with a trustworthy laboratory to preemptively combat this silent assassin. Email, call or text Abraxas Labs to learn more and be ahead of the game in protecting your crop!

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Table of Contents

  1. HLVd Introduction
  2. Pneumonic To Remember
  3. How is (HLVd) spread controlled?
  4. Detection and Management of HLVd Infection
  5. How can Hop Latent Viroid be controlled?
  6. Final Thoughts

What is Hop latent viroid (HLVd)?

Are you a cannabis cultivator or processor dealing with the silent enemy, Hop Latent Viroid (HLVd)? It is a little-known viroid that quietly infiltrates cannabis plants and can significantly dent your yield and overall revenue. HLVd's sly, difficult-to-detect nature makes molecular testing essential in preventing considerable financial losses for growers. Although plants with HLVd may not show any symptoms, those that do will normally have a lower yield of cannabinoids, reduced terpene content and reduced overall yield. This can cause a significant financial loss for growers, which is why it's becoming increasingly important for cannabis operators to test for HLVd early on. Don't let HLVd sneak up on you! Make sure to entrust your samples to a reputable laboratory and detect HLVd before it causes any damage.

At Abraxas Labs, we've created an easy-to-remember acronym, VITAL, to help you remember the key facts about an HLVd infection:

  1. Viroid structure
  2. Impacts on yield and quality
  3. THC content reduction
  4. Acid and aroma alterations
  5. Latency and prevalence

Let's take a closer look at these areas:

  1. Viroid structure: HLVd is a small, RNA molecule. It is similar to viroids and is classified under the genus Cocadviroid [2]
  2. Impacts on yield and quality: HLVd significantly reduces hop yield and quality, leading to economic implications. Yield losses can range from 8% to 37.5%. In cannabis, HLVd infection can cause up to $4 billion in annual losses [7]

  3. THC content reduction: In cannabis plants, HLVd infection can cause a 50%-70% reduction in THC content, significantly reducing commercial value [1].

  4. Acid and aroma alterations: HLVd infection reduces α-bitter acid content and increases β-bitter acid content, leading to early hop cone maturation. Changes in α-bitter acid, β-bitter acid, oil content, and terpene profile can affect the aroma of your product. This is also true for terpene content (see discussion below)

  5. Latency and prevalence: HLVd doesn't typically show visible disease symptoms, hence the name "latent". Despite this, it is widespread, with a 90%-100% prevalence in European hop germplasms and an estimated 90% prevalence in California's cannabis-growing facilities.

How is (HLVd) spread controlled?

The primary method for controlling viroids, such as Hop Latent Viroid (HLVd) in cannabis, is by using viroid-free materials. The initial measure involves testing all incoming cannabis plants and products that could potentially carry HLVd. A 30-day quarantine is recommended for new plants, with testing for HLVd during the third week. While there isn't a chemical treatment for HLVd, techniques like meristem tip culture, thermotherapy, and cold treatment can significantly reduce viroid titer, with the meristem tip culture being shown as an effective approach to eliminating the virus. The most effective method combines cold treatment with meristem culture. Thermotherapy can rapidly decrease viroid titer, but it also leads to a significant increase in sequence variants in the HLVd population, resulting in increased chances of production of resistant strains. T

Young medical scientist working in modern lab, research with tubes and notebook

Detection and Management of HLVd Infection

The spread of the hop latent viroid (HLVd) primarily occurs via vegetative cuttings, contaminated tools, and mechanical means in hop yards or indoor cannabis-growing facilities. As there are no control measures for viroid-associated diseases, prevention relies on a multilayer management system. This includes timely identification and removal of infected plants, which is challenging due to the absence of visible symptoms.
Molecular detection methods like dot-blot hybridization, RT-PCR, and RT-qPCR are used for routine diagnosis. It's also crucial to sample multiple leaves and roots from different parts of the plant, as viroid distribution is uneven.

Tip: if you are collecting samples to bring to Abraxas Labs for testing, make sure to collect plant material from upper and lower parts of the plant

Recent findings from a small-scale study suggest that roots may serve as an effective sampling site for disease diagnosis, although similar studies find that leaves are sufficient for diagnosis [10]. Sampling multiple locations of the plant will result in a more comprehensive assessment of infection. Control is improved by removing all plants in a yard and replanting with certified viroid-free material. Viroid-infected plants must be destroyed, and in the case of indoor-grown cannabis, incineration or bleach treatment can eliminate HLVd. The sanitation of equipment, tools, and the vicinity of infected plants is critical. Heating blades at 160°C for 10 minutes and treating tools with a 5% household bleach solution or Virkon S are effective sanitation methods. High standard cultural practices and personal hygiene are also important in managing the spread of the viroid.



How can Hop Latent Viroid Infection be controlled?

HLVd can be eliminated from cannabis or hemp plants via tissue culture, but it is a lengthy and laborious process. As with most plant pathogens, prevention is key. The use of proper sanitation practices will go a long way in preventing the spread of HLVd and other plant pathogens. Handle plants with fresh gloves every time, and sterilize tools regularly. Before entering the growing area, visitors and staff should use footbaths and wear hairnets, beard nets, gloves, and coveralls. Before taking cuttings, cultivators should test mother plants for viroid infection with qPCR assays. To avoid introducing infected plants to their growing environment, cultivators should also screen incoming clones with qPCR assays. Additionally, more research is currently underway regarding the possibility that some cannabis cultivars may be resistant to the viroid and therefore, are good candidates for breeding and cloning since they may help prevent the plants from ever becoming symptomatic.


Final Thoughts

It's undeniable: our understanding of the Hop Latent Viroid (HLVd) has evolved significantly. Presently, our best line of defense – meristem tissue culture – is costly and labor-intensive, emphasizing the urgent need for proactive, molecular screening and diagnosis by an expert laboratory.
As we continue to delve deeper into HLVd's impact on the cannabis industry, it's essential to keep a vigilant eye on your crop and employ preventative measures. Stay informed, proactive, and rest assured knowing that Abraxas Labs is with you every step of the way in the fight against this silent saboteur.



  1. https://stratcann.com/insight/the-hop-latent-viroids-warning-shot-to-the-canadian-cannabis-industry/
  2. Adkar-Purushothama, C.R.; Sano, T.; Perreault, J.-P. Hop Latent Viroid: A Hidden Threat to the Cannabis Industry. Viruses 2023, 15, 681. https://doi.org/10.3390/v15030681
  3. https://stratcann.com/2021/04/01/the-hop-latent-viroids-warning-shot-to-the-canadian-cannabis-industry/
  4. https://www.thcfarmer.com/threads/what-to-do-with-duds.64342/
  5. Matoušek, J.; Patzak, J.; Orctová, L.; Schubert, J.; Vrba, L.; Steger, G.; Riesner, D. The variability of hop latent viroid as induced upon heat treatment. Virology 2001, 287, 349–358.
  6. https://www.plantcelltechnology.com/blog/everything-you-should-know-about-hop-latent-viroid-hplvd/
  7. https://www.cannabisbusinesstimes.com/news/cannabis-hop-latent-viroid-infections-dark-heart-nursery-crop-loss/
  8. Grudzi ´nska, M.; Solarska, E. The Elimination of viruses and hop latent viroid from hop (Humulus lupulus L.) in Poland. Acta Hortic. 2005, 668, 149–152.
  9. Eastwell, K.C.; Nelson, M.E. Occurrence of viroids in commercial hop (Humulus lupulus L.) production areas of Washington State. Plant Health Prog. 2007, 8. 
  10. Fernandez i Marti A, Parungao M, Hollin J, Selimotic B, Farrar G, Seyler T, Anand A, Ahmad R. A Novel, Precise and High-Throughput Technology for Viroid Detection in Cannabis (MFDetectTM). Viruses. 2023; 15(7):1487. https://doi.org/10.3390/v15071487