Latent Hop Viroid: A Hidden Threat to the Cannabis Industry
Since 2018, cannabis growers have been keeping a close eye on the dangerously infectious hop latent viroid (HpLVd). However, these precautions were not enough to prevent the spread of the viroid, or plant infection. Today, the sector faces a potential pandemic that could result in the loss of billions of dollars.
The researchers called the viroid of “greatest concern for cannabis and hop growers around the world”.
The difficulty with this viroid is that there is no way to prevent it from infecting plants. Even indoor growers have no environmental controls to combat it. Also, if present in a plant and not immediately recognized, it spreads rapidly.
The only thing growers can do is take preventive measures to stop the spread of the viroid. But this is not without difficulties. Moreover, it may be impossible to eliminate it.
According to Oussama Badad, co-founder and scientific director of Growmics, “the problem is that the cannabis industry, for at least 20 years, has only been based on clones. So everyone is shipping clones from place to place and no one is testing, or no one is aware of the methodology for testing this virus.”
Due to these trade measures, this viroid ended up all over the world. Especially wherever cannabis clones from California were shipped.
Effects of Latent Hop Viroid
Experts have figured out that the most common form of transmission of this viroid is through the use of cutting tools. However, this knowledge may not be sufficient to take protective measures. The viroid is stealthy in that it first appears asymptomatic.
The viroid first lodges in the roots of the plant, but quickly spreads to the leaves and flowers (within two to three weeks). This virus has often appeared in hydroponic crops, because it moves more easily through water.
Once infected, a plant does not die from the virus. However, it causes growth issues – cannabis looks shorter and trichomes fail to develop. Consequently, the plants also tend to exhibit lower levels tetrahydrocannabinol (THC) and cannabidiol (CBD).
Experts recommend testing the plants several times. The difficulty is that the test results may first be negative and then, a few weeks later, appear positive.
Rapid spread comes with financial losses
As we have seen, the viroid is most often spread via cutting tools. However, this propagation does not only come from these instruments.
Experts warn that the viroid probably settles in the soil of the cannabis plant (or in the water of hydroponics). Furthermore, it was discovered in seeds and moves through those who touch them. In the most subtle cases, it is enough for an infected plant to brush against a healthy plant for the virus to be transmitted.
And that's just the beginning. Insects that bore into plants can create other pathways for the virus. The viroid can spread through the air and end up in pollen.
The researchers found that in approved facilities in the United States and Canada, the virus appears in 25 to 50% of productions. According to other estimates, this figure is closer to 30%.
Either way, as Jeremy Warren, director of plant science for Oakland-based Dark Heart, points out: “That translates to more than $4 billion in annual losses for U.S. growers who had to produce more than 7 million legal cannabis in 2021.”
The good news is that research is finding ways to kill this viroid. A study conducted by the Dark Heart laboratory team eliminated the viroid in 31 strains.
However, this viroid is tough and will continue to persist. Many believe that it can never be completely eradicated. However, many are optimistic that it can be reduced to a low level so as not to harm the cannabis industry too much.