In 2017 Hop Latent Viroid (HpLVd) disease symptoms were noticed on multiple cultivars of Cannabis sativa plants grown in California, including stunting, malformation or chlorosis (yellowing) of leaves, brittle stems, and reduction in yields.
Additionally, cuttings taken from symptomatic plants for clonal propagation showed a reduced rooting success rate.
As the name suggests, Hop Latent Viroid (HpLVd) was first identified in hops. Ironically, infected hop plants are asymptomatic. In contrast, infected hemp plants (Cannabis sativa) are stunted and have brittle stems with less flower mass and trichomes.
Different modes of transmission have been identified for this pathogen. Damson-hop aphid, potato peach aphid, and green peach aphid are known vectors. Clones and transplants can also harbor the pathogen. Furthermore, HpLVd may also be transmitted by seeds.
Controlling the population of vectors can limit the spread of the disease in the field; but the main component of successful management of HpLVd is prevention. Using disease-free seeds and propagation material is the most effective way of avoiding HpLVd.