• Alexis Mellons

What is the Hop Latent Viroid?

The novel RNA virus that's deforming your crops, reducing your potency, and killing your bottom line


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Cuttings prepared for HLV testing at Summit Genetics Tulsa location
Summit Genetics has already begun testing all moms and clones for the hop latent viroid

What is the Hop Latent Viroid?

The Hop Latent Viroid, or HLV, is a novel RNA virus that’s plaguing gardens across the world, including commercial cannabis grows. First discovered in 2017 by Californian cannabis grower, Graham Farrar, HLV is likely the mysterious reason your plants haven't risen to their full potential. Though researchers believe this virus is widespread through the cannabis industry, you may not be aware this type of infection was possible!



Detecting the Hop Latent Viroid

The first step to prevention is detection! There are many signs and symptoms associated with the Hop Latent Viroid, but detecting the virus requires attention to detail and consistent interaction with your plants throughout the grow cycle.


The first challenge growers face in detection is simple unfamiliarity. While HLV is still becoming known, you may be trying to fix HLV-related problems with standard solutions, unaware of the fact your plants have a virus (and one that's actively spreading, at that). Another challenge facing HLV detection is its proclivity for lying dormant. The virus can spread slowly and with stealth until warmth, nutrients, or other pressure stimulates the virus into action. Plants that once seemed strong and healthy begin to lose their fervor before you know it, and for this reason, it's crucial to maintain a consistent search for symptoms.


So what are the symptoms of the Hop Latent Viroid? Collectively, the symptomology of HLV is known as "dudding," and includes:

  • Overall stunting

  • Chlorosis (yellowing of leaves)

  • Leaf deformation

  • Lateral/lazy branching

  • Brittle stems that are easy to pluck

  • Reduced flower mass and trichome number

  • Alteration of typical plant morphology


In the vegetative stage, you can recognize an HLV-infected plant as one that grows shorter (stunting) with smaller leaves and tighter node spacing (altered morphology). In flowering plants, you can recognize an infected plant if it has smaller, looser buds with much fewer trichomes. Though further testing will tell us more about the Hop Latent Viroid, existing studies suggest that HLV-infected cannabis crops produce only 70% of average yields and 50% of cannabinoid content. This leaves growers, at the end of a demanding growing season, with fewer pounds to sell and lower potencies to market; it's also the reason testing is becoming more and more crucial to cannabis grows around the world.


How the Hop Latent Viroid is Spread

The Hop Latent Viroid is spread primarily through transmission on tools and equipment during pruning and harvest. It's as simple as snipping an infected plant, then snipping a healthy plant, which is yet another reason cultivators should always sterilize their equipment before starting work on a new plant. The virus itself lives within the moisture of the plant's leaves and stems, so any moisture transferred can spread HLV.


The Hop Latent Viroid can also spread quietly during cloning, via cuttings taken from an infected mother. As we mentioned earlier, because symptoms of HLV are not always obvious, it can be hard to identify infected mother plants. This is especially true when infection occurs later in the plant’s development, as stunted growth will not be as apparent.


As with most plant pathogens, prevention is key to managing infection, and comprehensive sanitation practices will go a long way. Use fresh gloves each time you handle a new plant, and sterilize your tools often. For cannabis grows that go the extra mile, hairnets, beard nets, gloves, and coveralls are also great for keeping your plant rooms as clean as possible.



How to Prevent the Spread of the Hop Latent Viroid

As with all viruses, no curative therapies exist for Hop Latent Viroid infections in mature plants. Therefore, exclusion is the most important viroid management strategy, and diagnostic testing is the cornerstone of an effective management program. The growers at Summit Genetics are already in the process of testing all our plants for HLV, in order to identify and exclude affected plants from our facility. So rest assured you’re getting happier, healthier clones from our grow every time!


Do you have any questions about the Hop Latent Viroid or the testing process? Drop us a line! And stay tuned for more posts, as we dive deeper into how we test our plants and what we're learning from the process.


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