Cannabis COVID: the Rising Threat of HLVd in South Africa's Cannabis Industry Part 1 of 2

If you haven’t yet heard of  "The Hops" or HLVd (short for Hop Latent Viroid disease), and you're a cannabis cultivator, this article might shake your world up a bit. Given how fast it's spreading in South Africa, it's far better to be informed than caught off guard -and potentially lose everything.

HLVd has been dubbed the "COVID of cannabis" for good reason. Like COVID-19, it is highly infectious and a hotly debated topic among growers and academics alike. Some say, "It’s manageable," while others argue it’s changing cannabis cultivation forever. It shares other eerie similarities with the coronavirus: it seemed to appear out of nowhere, scientific consensus is elusive, and symptoms can vary dramatically from plant to plant, with one plant showing no signs, while its neighbour exhibits every symptom and must be culled.

Thankfully, researchers and growers agree on more than they disagree. This is part one of a two-part series. Be sure to read both to stay ahead of the curve.

What This Part Covers

In Part 1, we explore what HLVd is, how it affects cannabis plants, how to identify it, how it spreads, and why it matters. And if you still think it’s overblown, consider this: in 2023 alone, the legal cannabis market in North America reportedly lost R716 billion ($4 billion) due to HLVd. To put that into perspective, you would need to lose R4,000 per day since the year 1 AD only to go broke in 2025, that is over 2000 years of spending R4000 PER DAY just to equal what The legal industry lost in 2023 alone due to HLVd And that figure doesn’t even include the black-market losses in U.S. states where high taxes or criminalisation keep the illicit market alive.

What Is a Viroid?

A viroid is a small infectious RNA molecule — smaller than a virus and visible only under an electron microscope. Some viroids are latent (harmless), like those in chrysanthemums, while others are pathogenic, such as HLVd in cannabis. They are typically around 50 nanometers or smaller, roughly 2,000 times thinner than a human hair. Viroids infect a variety of plants including potatoes, avocados, and hops, causing devastating losses for farmers as no true cure exists.

This is a typical example of the horisontal growth seen in some HLVd plants

Where Did HLVd Come From?

Hop Latent Viroid originally affected hops — the vine that gives beer its distinctive flavor. In the 1950s, U.S. hops farmers reported strange symptoms, and the USDA identified a viroid as the cause. They mandated use of asymptomatic cultivars, which rendered HLVd latent in hops. Hops is the closest living relative to cannabis, and some growers have even grafted cannabis onto hops rootstock. So, it’s not surprising that HLVd eventually made the jump.

HLVd was officially identified in cannabis in 2019 at grow facilities in California. Before then, it was informally known as "dudding disease." Growers noticed plants that were slow, weak, and produced buds with low trichome density and weird or no terpene profiles. Dark Heart Nursery and Professor Dr. Zamir Punja (PhD, Plant Biotechnology, Simon Fraser University) have been instrumental in advancing our understanding of HLVd. A 2023 survey led by Punja estimated that over 90% of licensed California grows were infected. Due to its extreme contagion, many cultivators have resigned themselves to managing rather than eradicating it.

Even strict sanitation is often ineffective. For example, someone might touch an infected edible at home, then their phone or ring, and later spread the viroid by touching plant roots at work, even after washing their hands.

The South African Perspective

South Africa's cannabis regulatory landscape is a patchwork of half-hearted attempts. From legal export farms and a handful of Section 21 pharmacies dispensing THC as Schedule 6 medication, to thousands of black-market "dispensaries" and script mills — there's no central tracking or unified framework in South Africa. This makes it nearly impossible to quantify HLVd's spread.

These plants might not look too bad on photos until you realise that it's the same strain except the left plant is showing typical lack of chlorophyll production, has no smell and is airy, while the plant on the right is rock hard and smells like berries and candy

At NEWTS, we provide world class fertilizer solutions to both Large licensed farms,resellers and hobby growers and we've seen a sharp increase in suspected HLVd infections in the last 6 Months, since we first saw it with our own eyes in 2022. At the time, testing was hard to come by. Fortunately, local labs now offer PCR testing. We won’t publicly endorse a specific lab, but a quick search for "HLVd testing South Africa" will point you in the right direction. You can also contact us directly for assistance regarding consultation and testing should you feel a bit lost or overwhelmed.

Interestingly, Punja et al. (2025) discovered that PCR tests often return false negatives when sampling leaves. However, every sample tested positive when roots were tested, especially at the 250 base-pair RNA band. This is critical. Make sure your lab tests roots and older growth and targets the 250 bp RNA band.

How Is HLVd Spread?

Short answer: almost every way imaginable.

Zamir et al. (2025) found the viroid in:

• Roots, stalks, leaves, buds, and sap (even 4 weeks post-harvest)
• Runoff water
• Hydroponic systems
• Water splashed from soil or coco
• Growth media
• Pruning tools and cloning blades
• Shared water in clone domes and aeroponic systems
• Pollen (both natural and reversed)
• Seed coatings and inside seeds from infected parents (Other publications debate this but reading his article linked at the bottom might convince you otherwise.)

Although data on insect transmission in cannabis is limited, viroids in other plants are known to spread via sap-sucking insects. So, assume insects in your grow could be vectors and keep your IPM protocols airtight.

South African Field Symptoms vs. Global Reports

We’ve noticed that HLVd behaves slightly differently in South African grows compared to North America. It seems the viroid takes time to build up in local facilities. New infections often affect a small number of plants, but over time, entire crops become symptomatic.

Stress during early to mid-flower seems to trigger full-blown outbreaks. We've seen crops worth millions destroyed by this virus and investors at the point of tears. Some infected plants don't flower at all. Others stretch but only form tiny, trichome-free buds the size of rice grains.

Here we see the typical airy , weird leaved plant with little smell and sparse trichomes. This is usually a AAA+ plant that yields huge super potent frosty nugs!

Here's a comparison of global symptoms vs. South African observations made by NEWTS:

In Part 2, we will cover prevention strategies, sanitation protocols, and managing an infected grow. HLVd is a silent threat, but with knowledge and vigilance, you can stay ahead of it.

This is seen in late stage infections, weak, lime green plants that refuse to flower, yes this plant has been under 12/12 for almost 3 weeks yet produced about 8 pistils, the plants around it have good budset and are dark green,

Stay safe. Stay informed. Stay growing and remember Stick to what works!

The NEWTS Team

psssst....... PLANT NERDS, here's the link we promised: https://pmc.ncbi.nlm.nih.gov/articles/PMC11902214/