What is Hop Latent Viroid and how does it work?

For anyone growing cannabis, Hop Latent Viroid is something to look out for. It is an infectious RNA viroid  that affects cannabis and hemp. It is not known how the virus works exactly, but infection causes stunted growth and significant reduction in economically vital compounds like cannabinoids such as THC and CBD, as well as terpenes. Hop latent viroid infection is common and believed to surmount over $4B in damages annually in the cannabis industry alone (Dark Heart Nursery, 2021 Report).

With infection potential so high across the industry, this article will explain what HpLVD is, its primary symptoms, prevention methods, and how to manage an outbreak if one should occur.

1. HpLVD in Cannabis

Hop latent viroid is a single stranded, circular pathogenic RNA. Hop latent viroid is not only found in hops, cannabis’ sister species, as well as cannabis itself, but also in other plants such as barley and wheat. There are two main ways that hop latent viroid enters the plant: through infected seed or infected plant material. 

2. Symptoms of HpLVD in Cannabis

Just like the name implies, hop latent viroid stays latent in the plant until it blossoms into a cultivator’s nightmare. Symptoms can come on suddenly.”As with hops, symptoms include stunted growth, abnormal plant growth, deformed leaves, and reduced cannabinoid production. Some plants may also experience leaf rollers. If left untreated, these symptoms can be deadly and obliterate harvest potential. The infected leaves may drop off on their own accord, and the plant can die from a lack of nutrients and sunlight.

3. How is Hop Latent Viroid Spread?

Hop latent viroid is spread through infected seeds or contact with infected plant tissue. If you purchase seed from a reputable source, it is less likely to be infected. If you are purchasing clones, it is vital to test for presence of hop latent viroid to make sure you are not inadvertently bringing this pathogen into your grow. Testing, like with the LeafWorks Hop Latent Viroid ID test can confirm a clean clone quickly.

4. Prevention Methods

The primary prevention method against HpLVD in cannabis is to practice good hygiene around any cannabis growing operation.  Avoid cross contamination by using new gloves when handling plants, wash and sterilize any tools before you use them on a different plant, and be mindful of your clothing touching plants. Use different coveralls or lab coats when moving among different areas of cultivation. You should also be aware of your growing environment and what other plants are near your crop. If you notice any symptoms, isolate the plants immediately to prevent the further spread of HpLVD.

5. How to Manage an Outbreak

An outbreak of HpLVD in cannabis is difficult to treat, but it can be managed. While cold treatment has been shown to be possible in hops (Gradzinka et al. 2006), the best method is to test for hop latent viroid at the first onset of symptoms, isolate anyinfected plants from the rest of the crop, and move the plant immediately into tissue culture.

Think your cannabis operation may be infected? Use a LeafWorks Cannabis & Hemp Pathogen ID Tests and find out quickly and cost-effectively.