Hop Latent Viroid

Hop Latent Viroid (HLV) is a pathogen belonging to the Avsunviroidae family that infects cannabis and related plants. First identified in cannabis crops in North America around 2012, HLV is transmitted through contaminated tools, propagation material, and infected plant tissue rather than through seeds or pollen. The viroid causes stunted growth, leaf deformation, and reduced yields in susceptible plants, though symptom severity varies by host genotype and environmental conditions. HLV spreads readily in propagation-heavy breeding programs and commercial cultivation, making detection and quarantine protocols essential for maintaining genetic stock integrity. Unlike viruses, viroids contain no protein coat and consist solely of circular RNA, requiring different diagnostic approaches for reliable identification.

Breeders prioritize HLV-free stock verification through RT-PCR testing before integrating genetics into active programs, as viroid presence compromises phenotype stability and yield consistency across generations. Selection for natural resistance or tolerance traits is an ongoing focus in breeding lines developed for regions where HLV contamination poses persistent risk.