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Hops Latent Viroid Infection: A Concern for Cannabis Cultivators

cannabis plants

As the legalization of cannabis continues to expand across the United States, cultivators face numerous challenges when it comes to producing high-quality plants. One of the most concerning issues is the prevalence of hops latent viroid (HLVd) infection, which impacts over 30% of cannabis plants in the US. To date, PB Labs has found a 27.5% positivity rate in cannabis plants tested in New Mexico.

What is Hops Latent Viroid?

HLVd is a small, circular RNA molecule that infects hops and cannabis plants. The viroid is spread through “blood to blood” contact. If an infected plant has a cut or rip on one of its stems or leaves, it can transfer the viroid to another plant with a cut. The main way this occurs is through trimming tools that are not properly cleaned between plant trimmings. Once a plant is infected, HLVd can have severe impacts on its growth and development, including stunted growth and reduced production of flower and THC.

Why is HLVd a Concern for Cannabis Cultivators?

HLVd can be difficult to detect in cannabis plants because it often does not cause any visible symptoms until it has already spread throughout the entire plant. This means that infected plants can go unnoticed and spread the viroid to other plants, resulting in significant crop losses.

Additionally, HLVd can persist in plants even after they have been harvested and dried. This means that infected plants can contaminate drying rooms and equipment, as well as finished cannabis products, which can be problematic for both cultivators and consumers.

cannabis grow room

What Can Cultivators Do to Prevent HLVd Infection?

Preventing HLVd infection in cannabis plants requires a combination of preventative measures and careful monitoring. Here are some steps cultivators can take to minimize the risk of HLVd infection:

  1. Use disease-free clones or seeds to start new plants.

  2. Get new plants tested before introducing them to your grow rooms.

  3. Sanitize all tools and equipment with 10% bleach solution between uses to prevent contamination. Do not use isopropyl or ethanol for tool cleaning. This actually helps the viroid spread.

  4. Monitor plants regularly for signs of infection, such as yellowing, stunted growth, or reduced production.

  5. Quarantine or destroy infected plants to prevent the spread of the viroid to other plants.

  6. Consider using a laboratory to test plants for HLVd infection.


HLVd infection is a significant concern for cannabis cultivators in the US, with over 30% of plants estimated to be impacted. Preventing the spread of this viroid requires careful monitoring, proper sanitation, and taking steps to prevent contamination in the first place. By being proactive and vigilant, cultivators can protect their crops and produce high-quality cannabis products for consumers.

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