There is an extremely damaging virus sweeping across North America, infecting cannabis crops and drastically affecting crop quality and yield. You may not be familiar with the virus as it is relatively new to cannabis crops, with the earliest known infections emerging from California in 2017. 


It’s called the Hops Latent Viroid, and it’s being detected in LP grows all over Canada.


The 'virus', is actually a viroid, meaning that it is even smaller than a regular virus strain. The hops latent viroid (HpLVd) has historically affected hops, a genetic relative to cannabis. 


The latency aspect of the moniker comes from its ability to remain dormant in an asymptomatic plant. It was first detected in British Columbia, Canada a couple of years ago and is said to have infected nearly 40% of Canadian licensed producer's crops.


checking cannabis plants


How To Detect Hops Latent Viroid


Unfortunately for the home grower, the presence of the viroid can only be verified in a lab. The latency aspect of HpLVd makes it very difficult to detect, requiring testing of tissue samples by lab technicians in order to verify an infection. A plant infected with the virus can pass it on to a cloned offspring, or it is spread through the use of contaminated gardening tools like shears or scalpels. 


This is known to integrated pest management (IPM) specialists as mechanical transmission. HpLVd can lay dormant in a strain for several generations and can be transmitted by seed as well. Transmission via seed is said to be present in 8% of seeds from an infected plant.   


How Is The Virus Treated Once A Cannabis Plant Is Infected?


Cold and heat treatments on tissue culture samples are effective at eliminating the virus. Even in commercial cannabis production, these treatments can be costly and time consuming. The most effective way to manage HpLVd is to eliminate the infected plants. This is especially true for the home cannabis grower. Much like a parasite, HLV requires a host (cannabis plant) to live.  


cleaning with bleach



Effective Preventative Measures


The most effective preventative measure to stop the hops viroid from spreading is by using sterilized propagation equipment.  Future Harvest's Retrobrite Hydrogen Peroxide (H2O2) is highly effective for sterilization. A bath of 10% bleach and water solution will disinfect effectively as well, eliminating the presence of the viroid on gardening equipment.



H2O2 promotion for Future Harvest



In addition to sterilization, one should be very cautious when swapping genetics with other growers. This is because the disease is not easily detectable like fungal cannabis diseases or pest damage which can be diagnosed with the naked eye.  


image of virus on plant


Symptoms Of Hops Viroid


Plants infected with HpLVd may become stunted, with diminished yields, brittle branching, reduced flowering, diminished THC levels and trichome production. THC and cannabinoid production in infected plants has been shown to be reduced by 50-70%! The virus will continue to degrade cannabinoid production through generations of propagating infected mother plants. 


Unfortunately, there's really no way for home growers to be certain the viroid is causing stunted growth. Some cannabis strains are just genetically predisposed to grow shorter than others. 


Phenotypic traits of the same cannabis strain cause natural variation in growth characteristics, which can also be misleading.

Home gardeners have referred to HpLVd as 'dudding disease' for years. To the average cannabis grower, they are just dud cannabis plants. The grower is likely to move on from the strain in search of larger yielding plants. This may indirectly solve the infection problem by eradicating the infected plant.


medical cannabis


How Does Hops Latent Viroid Affect Licensed Producers?


For licensed producers, detection and eradication of the virus is not something to be taken lightly. The recreational market has dictated a demand for high THC cannabis, with rich terpene profiles. The Hops Latent Viroid can compromise the quality, quantity and vigor of a crop, representing unacceptable losses to an LP's bottom line. It is hard to fully quantify such losses yet due to the tight-lipped nature of the industry's close-guarded secrets.  


The suspected prevalence of the virus highlights the importance of sourcing disease-free genetics, and developing sterilization protocols into an integrated pest management regimen. A failure to identify the disease in a commercial setting could mean losing the competitive edge in the industry and millions of dollars in lost revenue.  


cannabis seeds


As the industry adapts to the spread of the Hops Latent Viroid, experts say they should also take it as a warning of potential pathogenic mutations that could affect crops in the future. Cannabis grown at a commercial scale in Canada is still quite new, and we are likely to see other viruses that adapt and spread through commercial production practices. 

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