This year taught us many lessons as cannabis farmers, one of them regarding the hop latent viroid. When we realized a large group of our plants showed stunted growth, we were lucky we caught it as early as we did and could get back on schedule with only a few weeks of delay. As the name suggests, the hop latent viroid (HpLVd) originated in hop plants. Cannabis is genetically related to hops and, therefore, was able to contract the viroid.
What’s most unfortunate is that while HpLVd doesn’t show symptoms in hop plants, it does in cannabis, and the symptoms are severe. Mutated leaf formations resembling a duck’s foot, a lack of robust root development, yellowing leaves and a slowed-down growth rate are all common signs of this viroid, but it’s easy to miss the symptoms early on since they won’t always boldly display until introduced to environmental stressors. If caught too late into their cultivation cycle, brittle stems, less flower mass and lower trichome development are common, fiercely dampening the final harvest output.
The one positive we gained from this experience was the lesson on tissue culture. This micropropagation method gathers plant media from a mother plant and places it in a sterile environment with a nutrient-rich gelling media that helps the plantlets develop healthy roots and shoots. Only a small piece of plant tissue is needed to produce hundreds of identical clones, and the culture can remain dormant until it’s ready for use. At this point, the addition of different hormones and nutrient solutions can be added to the culture to stimulate growth. When it’s large enough, hundreds of little pieces can be cut from it, producing clones that will soon be ready for planting. What’s even more extraordinary is HpLVd, as well as other viroids and pathogens, can be eradicated via the tissue culture process. So, this is precisely what we did for our one infected cultivar.
If we have genetics we wish to save, we don’t have to take up floor room in the garden. Instead, we can have them stored at a tissue culture lab. Much like cloning, any genetic that comes from tissue culture will be an exact replica of its mother plant, an important aspect for commercial cannabis producers who are expected to deliver a consistent, high-quality product every time. Tissue culture starts have proven to be more vigorous than cuttings taken through the typical cloning method, and while they may take a little longer to get started, there’s nearly no risk of cross-contamination.
With the future of cannabis cultivation continuing to move toward efficiency and consistency, micropropagation could one day become the most common cloning and genetic-preservation method.
Giving Tree Farms
Anderson Valley, CA