Hop latent viroid

Hop latent viroid (HLVd) is a small, circular, single-stranded RNA pathogen that infects hop plants and various Cannabis species. As a viroid, it lacks a protein coat and relies entirely on the host plant's replication machinery to propagate. It is a highly contagious disease that poses a significant threat to global hop and cannabis production.

The primary host for this pathogen is common hop (Humulus lupulus), though its recent emergence as a severe threat to cannabis crops has brought it into the spotlight of international agriculture. The term "latent" refers to its tendency to stay asymptomatic in some hosts, meaning the plants can carry and spread the infection without showing any obvious signs of distress.

Symptoms of HLVd infection are diverse. In hops, it causes reduced vigor, shortened internodes, and decreased yields. In cannabis, it is widely known as "dudding," causing stunted growth, leaf chlorosis, brittle stems, and a dramatic loss of trichome density and secondary metabolites, which severely impacts the commercial quality of the harvested product.

Transmission occurs through mechanical vectors, primarily agricultural tools, contaminated machinery, and physical contact between infected and healthy tissues. Because the viroid is highly stable, it can remain infectious on tools for extended periods if they are not properly sanitized. Additionally, it can be spread through infected vegetative cuttings, which is a major concern for the nursery industry.

The economic impact is profound, as HLVd infection is irreversible. Once a plant is infected, it remains a reservoir for the pathogen throughout its life. Because there are no chemical treatments available, management relies exclusively on strict biosecurity and proactive prevention measures to maintain disease-free cultivation environments.

• Utilizing certified disease-free propagation material from reputable suppliers.
• Strict sanitization protocols for all pruning and cultivation equipment using bleach or dedicated sterilants.
• Implementing regular diagnostic testing, particularly PCR assays, for mother stock.
• Quarantining all new plant arrivals before introducing them into the main crop area.
• Culling and destroying infected plants immediately upon discovery to prevent further spread.