Hop latent viroid (HLVd) is a viroid, a tiny circular RNA of about 256 nucleotides with no protein coat, that infects hops and cannabis. In cannabis it causes "dudding": plants that grow slowly, with shorter internodes, brittle stems, smaller and looser flowers, and less resin. Many infected plants show few or no symptoms for long periods, especially mothers in veg, which is how it spreads unnoticed.
In practice
HLVd moves in sap: on scissors, razors, hands and clones taken from infected mothers. It is also found in roots and recirculating solution, and seed transmission has been reported at low ratesbeing reviewed. Detection needs a lab test, typically RT-qPCR on root or leaf tissue. There is no cure for an infected plant. Clean-up relies on testing mothers, discarding positives, sterilising tools between plants, and recovering clean stock by meristem tip culture.
Myth check
"Clone decline" or "genetic drift" in old cuts is a pathogen story, not a genetics story. GenetixBay's house position is that there is zero genetic drift in kept cuts apart from pathogens such as HLVd; the founder keeps cuts more than 40 years old with no decline. Label: Supported. See HLVd and viruses and Mythbusters.
Don't confuse with
The smallest known plant pathogen: a short circular RNA, usually 246-401 nucleotides, with no protein coat and no protein-coding genes, copied by the host's own enzymes.The length of stem between two adjacent nodes; short internodes mean compact plants and tight bud stacking, long ones mean stretch.A mother plant is a female kept permanently in vegetative growth to supply cuttings, so a selected genotype can be propagated as clones indefinitely.A recirculating (closed) system returns drained nutrient solution to the reservoir to be reused, saving water and nutrients but needing more monitoring and sanitation.Meristem culture is tissue culture from the tiny dome of dividing cells at a shoot tip, used to regenerate plants free of viroids and viruses.Genetic drift is random change in allele frequencies between generations of a seed population, strongest in small populations; clones do not drift this way.Nutrient lockout is when plants show deficiency symptoms although nutrients are present, because pH, salt build-up, ion antagonism or damaged roots stop uptake.In cannabis growing, a plant (usually female) that develops both pistillate and staminate flowers or anthers; botanists call it intersex or monoecious expression.An infectious particle of nucleic acid in a protein coat that replicates inside plant cells; on cannabis, often insect-spread and incurable once infected.Cleaning and disinfecting rooms, tools, containers, irrigation and people's clothing so that pests and pathogens are not carried from plant to plant or crop to crop.Holding incoming plants, clones or seeds apart from the main grow, under observation and sometimes treatment, until they are shown to be free of pests and disease.Using living natural enemies, such as predators, parasitoids, nematodes and microbes, to suppress pests and diseases instead of, or before, chemical sprays.
