Hop Latent Viroid or (HLVd) is an infectious single-stranded, circular RNA that is completely dependent on its host plant’s metabolism for replication. As the name suggests, HLVd occurs worldwide in hops, but it can also infect hop’s close relative – cannabis.
If your previously healthy plants have suddenly started becoming stunted or “dudded” ingrowth, then a Hop Latent Viroid infection may be the cause. The only way to truly confirm stunted growth is from HLVd, and not due to other causes is to get your plants
tested.
How to Spot HLVd
HLVd will greatly reduce the quality and quantity of the flower the infected plant produces. During the vegetative stage, plants will remain shorter with smaller leaves and more horizontal branching. Branches and leaves will become very fragile and tend to break off easily. Flowering plants will have smaller, looser buds with much fewer trichomes and reduced terpene production.
How does it spread?
HLVd is most commonly spread via infected pruning tools. It’s critical cultivators always sterilize their equipment before starting work on a new plant. HLVd can also spread through cloning when cuttings are taken from an infected mother. And because symptoms of HLVd 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 since stunted growth will not be as apparent.
How to prevent it from spreading?
Conception Nurseries screens all cultivars coming into the lab with a full cannabis virus/viroid panel. We then eliminate any plants that test positive for viruses/viroids and if all of the plants test positive we are able to eliminate them through the meristem tissue culture process.
By starting with tissue culture clones that have been tested and verified to be pest and pathogen-free, you minimize the risk of HLVd.
As with most plant pathogens, prevention is key. Good sanitation practices will go a long way in preventing the spread of HLVd and all other plant pathogens. Use fresh gloves each time you handle a new plant and sterilize tools by letting the tools sit in a 10% bleach solution for 2-5 minutes and then rinse with clean water before switching plants. Isopropyl alcohol is not strong enough. Use bleach. Cultivators should also screen plants with PCR tests when there are symptoms that match HLVd, to eliminate infected plants from your grow.
ABOUT THE AUTHOR
David Stormzand is the Customer Success Manager at Conception Nurseries. He has spent the last 12 years running commercial grows in California, Oregon, Colorado, and Michigan.