How does Hop latent viroid spread between cannabis plants?

Hop latent viroid transmission methods

Mechanical transmission

One of the most common ways HLVd spreads within a cultivation facility is through mechanical transmission. When trimming infected plants, sap from the infected plant can access microtears or wounds on healthy plants, leading to hop latent viroid transmission. Proper sterilization of tools after trimming infected plants is crucial to prevent the rapid spread to healthy plants.

Physical transmission

Physical transmission of hop latent viroid (HLVd) in cannabis plants can occur through direct contact with infected plant material. If sap or plant debris from infected plants contaminates the hands or clothing of employees/visitors, there is a potential risk of transmitting HLVd. Although this mode of transmission is less common compared to other methods, it is still essential to practice good hygiene and take preventive measures. Sanitizing gloved hands between handling plants can help minimize the risk of spreading HLVd during cultivation operations, ensuring that healthy plants are not contaminated by contact with infected material. While HLVd does not survive for longer than a few hours on bare skin, thoroughly washing hands and/or using gloves before touching plants is highly recommended to limit pathogen introduction.

Seed transmission

While the frequency of seed transmission in cannabis is not extensively studied, hop plants have shown a seed transmission rate of approximately 8% for HLVd. (1) Ongoing research is being conducted to determine the rate of seed transmission in cannabis plants. Monitoring the presence of hop latent viroid in seeds by molecular testing and employing appropriate preventive measures can help limit seed-borne transmission.

Water transmission

Another potential route of hop latent viroid transmission is through water. Viroids, including HLVd, are concentrated in the roots (2) and can move into runoff water(3). If recirculating or shared water sources are utilized, contaminated water can spread the viroid to healthy plants. Growers should be cautious and consider water sources when managing the risk of hop latent viroid transmission. Simple measures, such as organizing clones of the same variety together in the same clonal tray, can go a long way to limiting water transmission between varieties.

Insect transmission

While there are no current published reports demonstrating insect transmission of HLVd, it is highly likely given the transmission patterns of other viroids. Insects can play a significant role in spreading various viroids, viruses, and other pathogens. Limiting insects' access to cannabis plants should be standard practice for growers to mitigate the risk of hop latent viroid transmission and prevent the spread of other harmful agents.

Pathogenic fungi-supported transmission

Recent reports suggest that pathogenic fungi, such as Fusarium, could support viroid replication and contribute to the spread of HLVd in host plants(4). While fungal pathogens can be damaging in their own right, controlling the prevalence of pathogenic fungi may also help reduce hop latent viroid transmission. Implementing rigorous sanitation practices, maintaining proper environmental controls, and routine screening for pathogenic fungi are crucial for minimizing the overall vulnerability of cannabis plants to HLVd and related diseases.

Hop latent viroid poses a significant threat to the cannabis industry, and its asymptomatic nature makes it challenging to control and eliminate. Understanding Hop latent viroid transmission methods is crucial for growers to develop effective prevention and control strategies. Mechanical transmission through tools, physical interaction, potential seed transmission, water transmission, and the possibility of insect-mediated or airborne pollen transmission are important factors to consider.

Additionally, controlling pathogenic fungi can indirectly contribute to limiting hop latent viroid transmission. By adopting robust sanitation practices, implementing integrated pest management strategies, and maintaining a clean growing environment, growers can mitigate the risk of hop latent viroid transmission and protect their cannabis crops.

For more information on Hop Latent Viroid, read Everything you need to know about Hop Latent Viroid.

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About TUMI Genomics

TUMI Genomics is advancing cannabis cultivation by bringing biological insights to help commercial growers thrive. Through comprehensive preventative solutions, superior pathogen diagnostics, and AI-driven insights, TUMI Genomics is helping cultivators start clean and stay clean. The unrivaled diagnostics, transparent validation and industry-leading pathogen detection innovations provided by TUMI Genomics are raising the standards of commercial cannabis cultivation. The team at TUMI Genomics is composed of deeply experienced Ph.D. molecular biologists, bioinformaticians, business strategists, and accomplished serial entrepreneurs.

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