Hop Latent Viroid

What is Hop Latent Viroid?
Hop latent viroid, often abbreviated as HLV or HLVd, is a highly transmissible pathogenic agent that originated in hops, and was discovered in cannabis in 2019. It is a small, circular RNA molecule responsible for causing diseases in various crops. 

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How is Hop Latent Viroid Spread?

The primary method of HLV transmission is mechanical, typically through the use of contaminated tools. However, it's important to note that transmission can also occur from having sap from infected plants on clothing, hands, or gloves and subsequently touching a viroid-free plant. It is suspected that insects might play a role in the manual transmission of the viroid through their mouthparts, but further research needs to be conducted in this area to confirm this.

 

Additionally, there is evidence that suggested HLV can be transmitted through alternative routes, such as contaminated water sources and via seeds produced from infected plants. Viroid is prevalent in plants' roots, so it is possible that a water source shared between infected and non-infected plants could lead to transmission. 

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Why Does Hop Latent Viroid Matter to Cannabis Cultivators?

HLV is alarmingly prevalent in cannabis. According to Tumi Genomics it appears to be indicative of a "cannabis pandemic."  Tumi's research has revealed that this viroid is present in approximately 75% of facilities across the United States, Canada, and Europe*. In a separate study conducted by Dark Heart Nursery, it was suggested that as much as 90% of California's cannabis facilities test positive for HLV. The detrimental impact of this viroid on yields has been estimated to account for a staggering $4 billion in lost revenue across the cannabis industry.*

In short, HLV can have severe economic and crop loss implications for cannabis cultivators. It can affect plant health, reduce yields, and compromise flower quality. Early detection and management are paramount to prevent the viroid's widespread infection within your cannabis crops.

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Symptoms of HLV Infection:
You must test plants to verify they have HLV, infection cannot be confirmed visually. However, there are some symptoms that you might look out for when deciding if you want to test your plants. Common symptoms include stunted growth, leaf discoloration, decreased yield, reduced trichomes or reduced cannabinoid content. 

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Kaprikorn's Prevention and Management Strategies

Testing

• Kaprikorn has been testing mother plants for HLV since 2019. Consistent and rigorous testing is essential.

• Kaprikorn strives to obtain new genetics as cuttings, from stock plants that are test-negative at the time of cutting. After rooting, the new plants are then tested continuously every 3 weeks for the first 3 months to ensure they are clean.

• New genetics arriving in clone or seed form from untested sources are initially quarantined outside the mom greenhouse for 1-2 months and tested multiple times.  They are then tested continuously every 3 weeks for the first 6 months after entering the greenhouse to ensure they are clean.

• Verified test-negative strains are tested at least once annually.   Kaprikorn's results can be viewed, here

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Sanitation and Internal Protocols

• Between pruning or cloning on every mother plant, Kaprikorn's team uses sanitized tools. Tools are submerged in a 20% bleach solution for at least one minute--this kills the viroid. 

• Cut on plants from youngest to oldest. Older plants are the most likely to develop infection over their lifetime. 

• Keep mother plants on irrigation to avoid touching hundreds of plants with a single hose

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Additional Resources:
For more information and support on managing HLV in the cannabis industry, you can refer to the following resources:

• More detailed information about HLV

• View the study Kaprikorn did with Tumi Genomics to help identify the tissue type that most reliably predicts infection.