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  • Writer's pictureAlexis Mellons

Common Symptoms of the Hop Latent Viroid in Cannabis

Infection, Detection, and Protection: Stop the Spread of HLV by Recognizing the Symptoms in Your Cannabis Grow

The Hop Latent Viroid (HLV) is a flourishing virus that’s been plaguing commercial cannabis grows across the world since 2017. Though it won’t completely decimate your crops, there are serious effects to be aware of that cause long-term damage to your operation, your product, and your budget. Stunted yields, reduced vitality, and lowered THC potency are just a couple of HLV’s long-term effects, and with its eager ability to spread, you may see an entire room of healthy plants whittle into a slouching, lustless harvest from just one infected cannabis clone.

Recognizing the warning signs for HLV is imperative to containing and ultimately eliminating the viroid from your commercial grow. Detection requires attention to detail and consistent interaction with your plants throughout the growth cycle; so what are the symptoms of the Hop Latent Viroid? Collectively, the symptomology of HLV is known as "dudding," and includes:

Comparison of a healthy and HLV-infected cannabis plant
Stunted yields, reduced vitality, and lowered THC potency are just a couple of HLV’s long-term effects

Lateral Branching

Lateral branching is seen in the twisting or turning, the overall weakness, of cannabis stems. Rather than reaching up to the sky (or, likely, grow lights), they face forward, lazily hanging to the side. When looking at a cannabis plant, you shouldn’t be looking at the full face of the cannabis leaves. If you’re starting to see this on many branches of a single cannabis plant, you may consider testing the plant for HLV.

Leaf Deformation

Cannabis leaves will tell you a lot about the mother’s health, if you’re listening. With an HLV infection, leaf deformation comes in many colors. Commonly, cannabis leaves will curl at the ends, dried up and shriveled at every important corner of a leaf’s shape. Leaves will also lose their flat, stable structure, as they begin to round around each vein, almost making themselves “plushy.” As malnourishment sets into the plant, a sheen will add a waxy characteristic to the leaves. Not only this, but leaves will grow smaller, with possible variations in shape and shorter spaces between nodes. These are all warning signs for leaf deformation due to the hop latent viroid and are definite signs you should have a plant tested.

Comparison of a healthy and HLV-infected cannabis plant
Infected cannabis leaves will curl at the ends, lose their flat structure, and develop a waxy sheen.

Overall Stunting

Stunting is precisely what it sounds like. During the vegetative state, if you notice a single short plant in a sea of taller brethren, you’d recognize a growth deformity. Stunted plants grow shorter, take much longer to grow, or “stall out” once infected by HLV. They’re puny, runty, and all around weaker.

Reduced Flower Mass and Trichome Production

Recognizing HLV in the flowering state is similar to the vegetative state, with some extra signs to watch. Lazy or wilting branches that can’t seem to hold themselves up is a big sign; your cannabis plant should hold itself up with pride, never to the side. As in veg, stems in flower should be strong and lively enough to reach for the light, not drooping at a downward angle. Leaves should be facing the light as well, not sagging forward (lateral leafing). Additionally, in flower, you’ll notice plants producing smaller or fewer buds (likely both). These buds might also have an undesirably loose structure, and most importantly, your trichome production will be greatly affected. Analyzing an entire crop, pay closer attention to the shiny, sticky, crystals atop your fresh flower. If a plant seems duller or lustless compared to others, this could be a sign of HLV infection.

This translates directly to the vitality of your plants overall, and ultimately to the quality of your final product. Cannabis plants infected with HLV test with up to 50% less cannabinoid and terpene production than a healthy plant, which means a lot to the industry. You might have to infuse your pre-rolls to bolster THC potency, reduce a whole crop to concentrate because the taste is terrible, or choose to trash an entire room because the testing is really that insignificant. With months of time, resources, and man power wasted, you were better off trashing a single sick cannabis clone at the first sign of illness.

Comparison of a healthy and HLV-infected cannabis plant
If a plant seems duller or lustless compared to others, this could be a sign of HLV infection.

Brittle Stems

Dry, thin, and overall lifeless stems on your cannabis plant are another symptom of the hop latent viroid. These stems are easy to pluck—even brush away—and typically look lifeless to the naked eye. Even to mildly experienced growers, discerning when a stem is or isn’t up to the job should be easy. Brittle stems can indicate numerous deficiencies in cannabis, including potassium, boron, phosphorus, or simply water. Therefore, if this symptom is combined with other common HLV symptoms, then it’s time to get your plant tested.


Chlorosis is otherwise known as the “yellowing” of leaves during the vegetative state. This symptom isn’t uncommon in cannabis grows—or any other garden, nursery, or household in the world for that matter—but it is another symptom of HLV, so it’s something to watch. Chlorosis alone isn’t a strong sign HLV is present, but if combined with other symptoms, you might be ready for a lab test.

Alteration of Typical Plant morphology: The HLV Casserole

If a plant is showing curled leaves, lifeless stems, and lackluster flower, you might call it a “dud.” A lame duck. A waste of time. For scientific purposes, the culmination of these many symptoms would otherwise be known as “atypical morphology.” Certainly, if you’re noticing most of these symptoms in one plant, you might as well quarantine, even if just in case. This is another reason it’s important to watch over your crops consistently and often. Despite differences in strains—as it pertains to bud structure, overall shape, and trichome production—you should know if a Purple Punch is looking weak, comparatively, or a Super Lemon Haze isn’t producing to its potential.

But just as your time, money, blood/sweat/tears is an investment to the operation as a business, so are the plants to which you tend. The long-term health of your grow, and therefore your returns, is dependent on the prowess of your product. Less flower, and less potent flower, is the antithesis of the nutrients you feed them, the space they require, and the energy put in.

Comparison of a healthy and HLV-infected cannabis plant
If a plant is showing curled leaves, lifeless stems, and lackluster flower, it might be time to test your plants.

What Happens Next?

HLV may not assassinate your crop, and it may not make patients sick, but it is affecting your grow. The bottom line is, if you’re putting in the hard work, nutrients, environmental needs, and time that cannabis requires, and you continue to get less-than-desired results, it’s time you take a plant for HLV testing. Or, test it yourself! As soon as you can positively identify HLV in your grow, you can begin removing those plants from your rooms, making way for healthy plants only. Unfortunately, no curative therapies exist for Hop Latent Viroid infections in mature plants, so isolating infected plants is the only way to ensure the viroid can’t spread to healthy crops.

The growers at Summit Genetics have already begun testing for HLV in order to identify and exclude affected plants from our facility. So rest assured you’re getting happier, healthier clones from our grow every time! We’d love to answer your burning questions about the Hop Latent Viroid, so reach out any time if you want to chat, and follow us on Instagram to keep up with what else we’re doing!

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