Across the United States, growers of marijuana are experiencing a widespread disease affecting their plants. The disease is hop latent viroid (HpLVd). It made its way across the United States after coming out of California. The point of the plants crossing state lines was to promote the legal markets, but, unfortunately, the contaminated plants have infected other crops. In 2019, the disease was first made public, but many believe it’s been infecting plants since at least 2014. As far back as 2014, there have been reports of dubbing, which is stunted growth and a lack of both trichomes and secondary metabolites. All of this makes the plant less effective when smoked or ingested. What’s more, is that testing for HpLVd is practically non-existent when it comes to cannabis plants.
Part of the rise of HpLVd infection is the lack of proper sanitation for both recreational and medicinal marijuana. What should be happening is both the sanitation and quarantine of new varieties of plants to prevent the rapid spread of the disease. HpLVd can be spread from plant to plant or from tools to plant. This means growers should be disinfecting their tools between each use. The most effective disinfectant is a 10 percent bleach solution to kill off pathogens. Gloves are another culprit for spreading the pathogen and need to be changed often.
The Cannabis Challenge Ahead
Unfortunately, the pathogen can spread without showing any symptoms it’s even there in the first place. This makes it even more important to practice aggressive sanitation and quarantine of plants. While the plants may appear ok, the disease could be lying dormant. In fact, plants test positive without showing any signs of viroid infection, which becomes a big problem in the cannabis industry and something that will affect the industry for many years to come. Another problem is holding onto the mother stock and cultivating from there. If the mother rooms are not properly maintained, these plants could be found continuously spreading the infection. For this reason, and many more, tissue cultures need to be tested for HpLVd and other diseases to establish a good growing stock of mother plants.
Furthermore, a big problem exists when parts of a mother plant test positive while others do not, proving the disease may not spread to the entire plant. This means you can test a plant and come up negative without knowing that other parts of the plant are infected. The plant can then test positive many months later. As a result, multiple negative tests are needed to deem the plant healthy.
How to Test for HpLVd
The best way to test for HpLVd is with a polymerase chain reaction (PCR) test. A PCR test checks for the presence or absence of a specific sequence in the DNA or RNA. This means it is possible to create a PCR test that tests specifically for HpLVd. As of now, the PCR test is not standardized, making some PCR tests more effective than others. In the meantime, growers need to adopt strict guidelines for sanitation and quarantine of plants.