A Guide To Understanding HPLVd/HPLV In Cannabis

Hop latent viroid (HPLVD) is a devastating pathogen that poses a serious threat to cannabis crops. First discovered in hop plants, HPLVD likely jumped to cannabis as it is the only other member of the cannabaceae plant family affected.

HPLVD can lead to substantial crop losses up to 30% and reductions in THC content from 50-70%. The viroid can remain latent for long periods, allowing significant damage before detection.

Once established, HPLVD spreads readily through contact, cloning, tools, and insects. The ease of transmission combined with a lengthy latent period enables HPLVD to infiltrate crops undetected.

While research is underway for long-term solutions like resistant cultivars, the best defense is vigilance. Growers should source clean clones, quarantine new plants, continuously test, and sanitize facilities.

Early detection through testing and preventative measures are critical to limit the devastation HPLVD can inflict through decreased cannabinoid content and crop losses. More research and collaboration is needed to combat this emerging threat to cannabis agriculture.

Hop Latent Viroid (HPLVD) as a microscopic threat to indoor marijuana crops
Hop Latent Viroid (HPLVD) as a microscopic threat to indoor marijuana crops

Symptoms and Effects of HPLVD

HPLVD infection causes several characteristic symptoms in cannabis plants:

  • Irregular branching
  • Decreased trichome production
  • Chlorosis – yellowing of leaves
  • Stunted growth

However, HPLVD can remain latent or dormant in cannabis plants for extended periods before symptoms emerge. This lengthy asymptomatic incubation enables the viroid to spread undetected as infected plants appear healthy.By the time symptoms manifest, HPLVD may have already inflicted significant damage. Impacts include:

  • 50-70% reduction in THC content
  • 20-30% yield losses

Key cannabinoids like THC and CBD accumulate in glandular trichomes on flowers and leaves. Decreased trichome production directly lowers cannabinoid levels. Photosynthetic impairment from chlorosis also reduces cannabinoid production.

Stunted plants with fewer branches produce smaller yields. Lower flower density further decreases yields.

Together, these effects can devastate cannabis crops. Facilities may only detect an HPLVD outbreak once plants show advanced symptoms.

Routine testing of asymptomatic plants is critical for early detection before the viroid becomes widespread. However, HPLVD’s lengthy incubation period enables the pathogen to embed itself before detection.

Once infected, facilities face major losses from:

  • Degraded flower quality
  • Reduced cannabinoid content
  • Lower yields

These impacts persist even in non-symptomatic plants. Strict preventative measures and vigilant testing are essential as symptoms alone cannot indicate if HPLVD is present.

While breeding for genetic resistance may someday control HPLVD, currently no cannabis cultivars are immune. Growers must act preemptively to exclude the viroid and contain any outbreaks before irreparable damage occurs.

Early detection and prevention are crucial against this stealthy pathogen. HPLVD’s asymptomatic spread enables it to inflict significant losses before detection. Ongoing research and collaboration is vital to counteract the emergence of this damaging crop disease.

Transmission of HPLVD

HPLVD likely jumped from hops to cannabis as they are the only two members of the Cannabaceae plant family affected by this viroid. Hops have long been infected with HPLVD, which probably evolved the ability to infect cannabis more recently.

Once introduced to cannabis, HPLVD spreads readily through:

  • Mechanical contact between plants
  • Using contaminated tools like pruners
  • Cloning infected cuttings
  • Sharing plant containers and hydroponic systems
  • Insects moving between plants
  • Potentially via seeds

HPLVD transmission occurs through direct contact with infected plant sap or tissue. Any mechanical action that disseminates sap, like pruning or cloning, spreads the viroid. Even minimal contact on tools or gloves enables transmission.

Shared containers and recirculating hydroponic systems rapidly disperse HPLVD. Insect feeding that breaches plant tissues also spreads the viroid.

While unproven, seed transmission could enable long distance spread. HPLVD’s aggressive transmission makes containing outbreaks challenging.

Strict sanitation and isolation protocols are essential, including:

  • Sterilizing tools and gloves between plants
  • Dedicated tools and gloves for infected areas
  • Separate plant containers and hydroponic systems
  • Insect control
  • Isolating symptomatic plants

Facilities should also:

  • Source clones from reputable, tested providers
  • Quarantine new plants and test before introduction
  • Discard infected plants and sanitize grow areas

Despite precautions, HPLVD persists and spreads stealthily. Continued research is needed to determine if seed transmission occurs and to develop resistant cultivars.

The combination of efficient transmission mechanisms and asymptomatic spread enables HPLVD to infiltrate cannabis crops undetected. Preventing introduction and limiting spread are critical against this emerging threat.

HPLVD Prevention and Control

Preventing HPLVD introduction and spread is critical as no treatments exist once plants are infected. Recommended prevention measures include:

  • Sourcing clones and seeds from reputable, tested providers
  • Quarantining new plants and testing for HPLVD before introduction
  • Isolating and regularly testing mother plants
  • Sanitizing tools, gloves, and facilities between plants

Tissue culture using meristem tissue can eliminate HPLVD. However, this technique is prohibitively expensive and technically challenging for most growers.

For existing infections, strict protocols limit spread:

  • Cull infected plants immediately
  • Isolate symptomatic plants
  • Dedicate tools, gloves, and containers to infected areas
  • Sterilize between uses in different areas
  • Control insects that may transmit HPLVD

Despite precautions, HPLVD may still spread undetected before symptoms emerge due to its long incubation period.

Ongoing testing using methods like PCR, ELISA, and next-generation sequencing is critical for early detection, especially among asymptomatic plants. Continuous testing of mother plants and new introductions is essential.In the long-term, breeding HPLVD-resistant cannabis cultivars offers the best solution. As HPLVD has likely adapted to cannabis only recently, selectively breeding resistant lines is plausible.

Until resistant cultivars are available, strict prevention and sanitation protocols provide the best defense. However, HPLVD’s efficient transmission and stealthy spread make containment difficult.

Vigilance and collaboration among growers is vital to prevent HPLVD’s emergence. With no current treatment options, prevention and early detection through robust testing are the only ways to protect crops against this damaging pathogen.

Testing for HPLVD

Early detection of HPLVD is critical to prevent crop losses, so growers should implement robust testing protocols. Recommended methods include:

  • PCR – polymerase chain reaction detects HPLVD genetic material. Highly sensitive and specific but expensive.
  • ELISA – enzyme-linked immunosorbent assay uses antibodies to detect HPLVD proteins. Rapid and affordable but less sensitive.
  • Next-generation sequencing – provides full sequence information to detect and characterize HPLVD strains. Costly but may detect novel variants.
Testing MethodDescription
PCRDetects genetic material, highly sensitive and specific, expensive
ELISAUses antibodies, rapid and affordable, less sensitive
Next-generation sequencingProvides full sequence, costly, detects novel variants
Table showing testing methods for HPLVD/HPLV

Key factors for effective testing include:

  • Test both symptomatic and asymptomatic plants – long latency period
  • Select representative samples from different areas
  • Retest mothers and newcomers every 2-4 weeks
  • Isolate and retest positives to prevent false results
  • Combine methods for optimal detection

Early detection enables:

  • Culling infected plants before widespread transmission
  • Isolating positives to prevent further spread
  • Increased vigilance in affected areas
  • Evaluating and refining prevention protocols

Without testing, HPLVD may become endemic before detection. Consistent testing and strict responses to positives is critical.

Ongoing research to improve testing methods and establish action thresholds should guide best practices. However, any detection should trigger immediate quarantine and retesting.

With no treatment options available, early detection through regular, rigorous testing is the only way to protect crops and limit losses from this destructive pathogen. Testing is a vital component of an integrated pest management program.


The emergence of HPLVD poses a serious threat to cannabis crops through both direct damage and unseen transmission. This viroid can inflict significant losses including:

  • 50-70% reductions in potency and THC content
  • 20-30% decreases in crop yield
  • Impaired flower quality from stunted growth and poor trichome production

HPLVD spreads readily through cloning, mechanical contact, shared tools and systems, and potentially via seeds. It can remain latent for extended periods, enabling undetected infiltration throughout facilities.Strict prevention measures are critical to exclude HPLVD:

  • Source verified, tested clones and seeds
  • Quarantine and test new plants
  • Isolate and regularly retest mother plants
  • Sanitize tools, gloves, and grow areas

For facilities already affected, robust testing and quarantine procedures limit spread. However, HPLVD may persist due to its efficient transmission and long incubation period.

Ongoing research is vital to:

  • Improve diagnostic testing accuracy and speed
  • Develop HPLVD-resistant cannabis cultivars
  • Enhance sanitation protocols
  • Raise awareness among growers

Open communication and collaboration will also help identify and implement best practices.

While HPLVD poses a formidable challenge, vigilance and preventative action can restrict its impact. Growers must act swiftly and decisively when HPLVD is detected.

With no treatment options, exclusion and containment are the only current defenses against this destructive emerging pathogen. Proactive measures and continued research offer hope to combat HPLVD and protect the legal cannabis industry against catastrophic losses.

What is Hop Latent Viroid (HPLVD)?

Marijuana FAQ

HPLVD is a single-stranded, circular RNA pathogen that infects cannabis and hop plants, causing the disease known as “dudding”. It reduces crop yields and cannabinoid content.

What are the symptoms of HPLVD infection in cannabis plants?

Marijuana FAQ

In cannabis, HPLVD infection causes irregular branching, decreased trichome production, chlorosis, overall stunted growth, and up to 70% reductions in THC content.

How is HPLVD transmitted between cannabis plants?

Marijuana FAQ

HPLVD spreads through mechanical contact, cloning infected plants, using contaminated tools, insects, hydroponics systems, and possibly seeds.

What is the impact of HPLVD on cannabis yield and potency?

Marijuana FAQ

HPLVD can remain latent for long periods, then emerge to cause up to 30% crop losses and 50-70% reductions in THC and other cannabinoids.

Can HPLVD be cured or treated in infected cannabis plants?

Marijuana FAQ

There is no treatment for HPLVD infection, but meristem tissue culture can eliminate it from plants. This is expensive and technically challenging.

How can cannabis growers prevent HPLVD infection?

Marijuana FAQ

Growers should source clean clones, quarantine new plants, sanitize tools and facilities, and continuously test mother plants to prevent HPLVD infection.

What are the testing methods to detect HPLVD in cannabis plants?

Marijuana FAQ

HPLVD can be detected through PCR, ELISA serological testing, next-generation sequencing, and other molecular methods.

How did HPLVD spread from hops to cannabis plants?

Marijuana FAQ

HPLVD likely jumped from hops, the only other member of the Cannabaceae plant family it naturally infects.

Is HPLVD a threat to other plants besides cannabis and hops?

Marijuana FAQ

Currently HPLVD only infects hops and cannabis, but could potentially evolve to affect other plant species.

Are there HPLVD-resistant cannabis cultivars being developed?

Marijuana FAQ

Yes, researchers are working to breed HPLVD-resistant cannabis cultivars as a long-term solution. Check with your favorite genetics dealer.

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