Systemic pathogens

Hop Latent Viroid (HLVd)

Hop latent viroid is an infectious RNA agent documented in cannabis. Symptoms can include reduced vigor and yield, but plants may also be asymptomatic; visual inspection cannot confirm infection.

What to look for

  • Unexplained loss of vigor or reduced performance in some infected plants
  • Inconsistent expression, including plants with few obvious visual symptoms
  • Patterns associated with shared propagation material or contaminated cutting practices

Important look-alikes

  • Root stress
  • Nutritional problems
  • Genetic variation
  • Environmental stress
  • Other systemic pathogens

How to confirm

  • Use validated laboratory testing such as appropriate nucleic-acid amplification assays
  • Test source plants and propagation stock rather than relying on symptoms
  • Investigate sanitation and propagation links among positives

Management principles

  • Isolate confirmed positives
  • Use clean tested stock for propagation
  • Follow validated sanitation procedures for cutting tools and propagation workflows

Prevention

  • Establish testing protocols for mother stock
  • Control movement of plant material
  • Sanitize tools between plants using validated methods
  • Maintain traceable propagation records

Visual study guide

  • Transmission pathway diagram
  • Testing workflow
  • Symptomatic versus asymptomatic concept panel
  • Clean-stock propagation map

Evidence & further reading

Sources connected to this lesson

These references support specific biological, diagnostic, environmental, or process concepts used in this lesson. They are not a substitute for crop-specific testing or local regulatory guidance.