Chris Butler
CEO
Giving Tree Farms
Anderson Valley, CA
About three weeks after transplanting our young plants into pots this year, we noticed a few rows weren’t growing as quickly as their neighbors. Their leaves’ configuration even looked different, resembling a duck’s foot with how tightly close together the leaflets sat. But it wasn’t until we dug a little deeper and looked below the soil that we saw something really strange.
We saw a lack of root development, and because the issue wasn’t so easily expressed above ground, we wouldn’t have noticed the stunting displayed on this group of plants without the side-by-side comparison until it was much further into the cultivation cycle. If it had been allowed to go that far, we would have seen a decrease in our yield and our overall quality. We really dodged a bullet.
So, what on earth was going on? The hop latent viroid.
The hop latent viroid (HpLVd) originates from hop plants but is asymptomatic when present. Cannabis, being genetically related to hops, was able to contract this viroid, and unfortunately, the cannabis plant expresses symptoms that significantly impact its growth quality and rate. Signs of HpLVd in the cannabis plant can be seen as stunted growth, brittle stems, less flower mass, lower trichome development, slow to no root growth and yellowing of leaves.
The symptoms can be all over the place, and sometimes won’t boldly display until they are well into their cultivation cycle or are introduced to environmental stressors. It’s super insidious in this way, especially considering the first place you look probably won’t be the roots because the plants will still uptake nitrogen. Cannabis plants with HpLVd will run into yield and quality problems down the road and will risk transmitting the viroid to other plants. With that in mind, we quickly replaced the contaminated plants with new ones and took the couple week delay to ensure we didn’t face a terrible fate.
HpLVd can be transmitted by cutting infected and non-infected clones with the same scalpel and through cross-breeding viroid-containing cultivars for seed production. In fact, it’s now estimated that 8% of all cannabis seeds have HpLVd. It’s because of this that many nurseries and seed banks could be unknowingly passing the viroid on to their customers due to a lack of research on this topic and a lot of unknowns regarding transmission.
One avenue to prevent the spread is through the use of tissue culture. We had one of our cultivars sent to a tissue culture lab to ensure future cuttings of it won’t contain HpLVd. The tissue culture lab searches for the viroid, then eliminates it if found. Going forward, we will be utilizing our tissue culture lab to ensure we don’t run into this problem again.