When it comes to hop latent viroid, there’s a lot of bad news for cannabis growers, unfortunately.
This was the message Dr. Zamir Punja, professor of plant pathology and biotechnology at Simon Fraser University, shared with 2023 Cannabis Business Times Conference attendees about hop latent viroid (HpLVd), an increasingly prevalent and persistent disease that has significantly cut into cultivators’ profits.
Many growers have cited it as one of the top cultivation challenges in commercial cannabis production.
However, Punja, who has been researching cannabis pathogens since 2018, says there are management strategies and resistant cultivars that can help cultivators mitigate the disease.
In his presentation at Cannabis Business Times Conference, which took place at the Paris Las Vegas in August, he outlined key points including the symptoms, severity, spread and survival of HpLVd, which is a double-strand ribonucleic acid (RNA) virus that gives it stability and makes it challenging to eliminate. For example, he noted that he had 18-month-old dried flower samples that still tested positive for the pathogen.
HpLVd can live on many surfaces and spreads easily, from mother plants into cuttings, from stems into roots and from roots into the plant, creating systemic infection. He said their research at Simon Fraser University also shows it spreads through water and shared irrigation and fertigation lines, and seeds.
Often plants aren’t symptomatic until the flowering stage, when cultivators first find stunted growth, smaller leaves, smaller internodes, smaller flowers, which is where the term “dudders” originated – what people called the symptoms before the culprit was identified. Yields are significantly reduced.
“When you’ve taken off your flowers, you’ve dried them, and you realize when you compare it to a healthy plant, the flowers are smaller, they are lighter and they yield a lot less cannabinoids then they would in a healthy cannabis plant,” he says. “So this is where it hurts and this is where the dollars are going out the window when you see hop latent infected flowers.”
Punja and his colleagues discovered in the research that trichome development is also stunted, which creates the reduction in cannabinoids and potency.
Understanding how the disease spreads is important and one way that growers can implement strategies to prevent an outbreak among their plants.
In a follow-up interview with Cannabis Business Times, Punja noted that testing multiple parts of the plant is crucial for identification. Sometimes a plant’s bottom leaves will test positive for HpLVd, but not the top, for example. He suggests using polymerase chain reaction (PCR) tests on three different portions of the plant and two weeks apart to ensure plants are disease-free. In addition, his work and those of other labs have also shown that testing roots can provide an accurate indication of the presence of hop latent viroid.
If a plant becomes infected, Punja and others say the safest bet is to destroy the plant to prevent spread, though that strategy may change if a mother plant tests positive. Because of the strong stability of HpLVd, Punja has found that a 10% to 20% bleach solution has shown to be effective in properly sanitizing surfaces and tools.
Punja says they are finding that certain cultivars are more susceptible to the disease, and likewise, there are others that are incredibly resistant.
“Many growers have observed that some strains get hop latent viroid more than others. This is the way to the future. This is the way we can eliminate this organism, is through breeding,” Punja says. “We don’t know how, but they have the ability to withstand the infection. Also testing, you’ve got to test, test, test to make sure particular strains are not infected.”
Over the years, Cannabis Business Times has published several articles with information on HpLVd, and the industry has come a long way since "dudders" was first observed. Here’s a roundup of those resources and articles from before the pathogen was identified.
Keep checking back for more resources on how to manage this pathogen, and stay tuned for updates about sessions for the 2024 Cannabis Business Times Conference, Aug. 20-22, 2024.
Diagnosis and Remediation
Dr. Zamir Punja, a professor of plant biotechnology at Simon Fraser University, explains what he’s uncovered in his recent research.
Curly Leaves, Stunted Plants, and More: 4 Potential Culprits
How to prevent and diagnose the most common pathogens that disrupt cannabis growth and development
Reports
Dark Heart Nursery Research Finds 90% of California Facilities Test Positive for Hop Latent Viroid
The nursery estimates $4 billion in annual crop losses industry-wide.
Hop Latent Viroid Infiltrates Vermont Cannabis Grow Site
The state’s Cannabis Control Board is warning licensees of the highly contagious pathogen and encouraging growers to take preventative measures.
Before HpLVd was Identified
The Threat of Viral Cannabis Diseases
Growers worldwide are seeing Cannabis disease symptoms with unknown causes among their crops. Here’s what we know about potential causes, detection and what you can do to stop viral spread.
Cultivators have been forced to make decisions based on community consensus, but legalization has opened the door to fact-based knowledge.
