Pcr positive at that point, the nursery they came from was arguing that there was no way.
We have one awesome guy that’s works with us that can pick them out of clone trays. He says the leaves have a box shape and that’s what he sees.
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Runtz and
Is it possible to grow a plant with the viroid that doesnt express symptoms in flower? Or will it “dud” out in some way almost all the time?
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yes. that is where “latent” comes into play. and what makes this particular critter so hard to deal with.
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As @cyclopath wrote, yes, it is. But that doesn’t mean the plant is healthy and is not affected by HLVd. Asymptomatic ≠ harmless.
HLVd was so named before scientists knew of the asymptomatic adverse effects, so it’s not truly “latent.” In hops, it’s my understanding that HLVd is always asymptomatic. According to Dr. Saldi from Tumi Genomics, initially calling the viroid “latent” was unfortunate because it always negatively impacts the plants, even when there are no visual symptoms (asymptomatic) like dudding in Cannabis (symptomatic).
A good example is HLVd’s asymptomatic impact on terpenes (in hops) that I posted a while ago. And it’s probably safe to assume HLVd could have similar asymptomatic effects in Cannabis:
Although HLVd-infected hop plants are symptomless, infection leads to a significant reduction in cone yield and bitter acids content in hop cones [11]. The yield was lower, from 8% to 35%, for infected plants of the cultivars Wye Challenger and Omega. The content of alpha bitter acids was reduced by 15% and 30%, whie the content of beta bitter acids was slightly higher. Follow-up experiments with Wye Challenger showed an 11% reduction of the yield, 11% reduction of the content of alpha bitter acids, and 8% increase of the content of beta bitter acids [12]. The reduction of alpha bitter acids’ content due to HLVd infection ranged from 20% to 50% within English hop cultivars and was genotype-dependent [13]. Similar results were found for hop cultivars Saaz, Premiant (40% reduction) [9]; Aurora (18% reduction) [8]; and Sybillla, Marynka, Pulawski, and Magnat (from 11% to 23% reduction) [14]. The content of beta bitter acids was slightly higher (0–5%) for all the cultivars. The loss of yield due to HLVd infection reached from 15% to 37.5% for Slovenian hop cultivars [8] and from 6.4% to 15.3% for Polish hop cultivars [14]. Viroid infection also influences the essential oils composition in hop cone, which contributes to the aroma flavor of beer. The increase of myrcene content by 38% for Wye Challenger-infected plants was first reported [12]. Similar results were found for hop cultivars Saaz and Premiant when the content of myrcene was increased by 29% together with monoterpene pinene isomers (about a 40% increase) for infected plants. On the contrary, all sesquiterpenes were reduced by 4.4% to 29% in cones of infected plants. From other compounds, terpene alcohols (linalool, geraniol, and methylgeranate) and epoxides were increased and ketones were decreased for infected plants [9]. Therefore, the composition of essential oils in hop cones is genotype-dependent and specific [15], and these changes cannot be general. Trends for the content of sesquiterpenes and monoterpenes (myrcene and β-pinene) were similar within Polish hop cultivars, with the exception of myrcene for cultivar Sybilla [14]. The content of linalool was higher for cultivars Sybillla, Lubelski, and Pulawski, but lower for cultivars Marynka and Magnat in cones of infected plants. The content of methylgeranate was lower for infected plants of all cultivars.
(NOTE: “HMVd” is a typo, the authors intended to write “HLVd.”)
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if YOU can’t see the symptoms, but someone else can, is it STILL asymptomatic?
I’m gonna go with: No. lack of symptoms is all abut how hard you look, you see none? by all means call it as “I see nothing!” (asymptomatic), but as soon as anyone can start listing measurable “symptoms”, it no longer makes sense to apply the term “asymptomatic”.
possibly, but for the wrong reasons…having gone back and read the original characterization paper, I’m gonna change my answer to @pangea (slightly).
in the case of THIS critter, “latent” meant “we didn’t notice symptoms”…not “there are no symptoms” nor (the definition I was working from) “there are two infection states”.
the canonical way to effect two infection states is to integrate into the host genome and wait. possibly for generations. THOSE are hard to deal with. this critter does NOT do that.
…and, if you can’t SEE the symptoms till you get the third party analytics back was that a healthy plant or not?!?
Edit: …and having learned that the gammaherpesviruses accomplish their latency by becoming histoned plasmids, I can leave for the day. 
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I’m not sure why you’re intermittently using capitalized words and excessive punctuation. I’m going to assume that maybe you had a bad day, or Donald Trump hacked your account. 
Common symptoms of HLVd in cannabis (1, 2):
- Stunting
- Outwardly horizontal plant structure
- Reduced flower mass and trichomes
- Malformation or chlorosis of leaves
- Brittle stems
Not everything is a disease symptom. For example, the negative effect on terpenes from HLVd in hops (or Cannabis) isn’t a symptom.
If a cannabis plant shows no symptoms associated with HLVd, but tests positive for HLVd, and the viroid negatively affects the host’s secondary metabolites, that’s asymptomatic (symptomless) harm.
The same is true for humans. For example, some self-reported asymptomatic individuals infected with COVID-19 seem to suffer subclinical lung abnormalities (harm). I.e., the classic ground-glass opacity (glass lung) distinctive for COVID-19-infected individuals. See:
No, of course, it isn’t. Once symptoms are noticed, it’s symptomatic by definition. But as I noted above, not all effects of a disease are symptoms of said disease. Ground-glass lung in humans with symptomatic and asymptomatic COVID infections is a great example.
However, note that in medicine, “symptom” and “sign” are typically (but not always) defined as subjective and objective, respectively. The patient (in our case, grower) notes symptoms while the physician (or plant pathologist) notices signs.
I responded to @pangea’s question, where he specifically asked about the visual symptom of dudding during flowering. And I’ll stick with my answer: Yes, some Cannabis plants (genotypes) infected with HLVd may remain asymptomatic (not dudding) throughout the flowering phase. See:
In February 2018 we sampled three symptomatic and three asymptomatic Cannabis plants suspected to host a viral agent from a farm in Santa Barbara County, CA. The symptoms included brittle stems, an outwardly horizontal plant structure and reduced flower mass and trichomes.
In February 2019 we sampled seven symptomatic and three asymptomatic plants from another farm in Alameda County, CA. RTPCR revealed the presence of HLVd in all symptomatic plants and one asymptomatic plant. Amplicons from four of these samples was Sanger sequenced and confirmed to be HLVd (MK791747-MK791750).
The consistent detection of HLVd alone in all symptomatic plants from both locations and its occurrence in only a few asymptomatic plants point to an association of the disease with the stunted Cannabis. HLVd can persist in hops without symptoms and Cannabis cultivators should take measures to minimize mechanical transmission while keeping in mind that HLVd may also be seed transmissible (Pethybridge et al, 2008). Considering the detrimental effects of HLVd to the commercially valuable secondary metabolites of the species, a thorough investigation of susceptibility, as well as range and expression of Cannabis stunting disease should be conducted at this important juncture.
When HLVd was identified, the author’s definition of “latent” was asymptomatic (symptomless), meaning “there are no symptoms.” HLVd was never considered a dormant (inactive) host genome integrated infection that would activate upon specific environmental stressors or growth phases. See the original 1988 paper:
That’s why HLVd isn’t a proper name, even though it’s asymptomatic in hops, because the viroid isn’t latent due to, for example, its harmful effects on secondary metabolites.
Another good read:
I think you are mistakenly equating HLVd disease “symptoms” with “effects.” While the differentiation is murky, to be sure, adverse effects on secondary metabolites isn’t a symptom of HLVd disease - it’s a disease effect - unless you’re referring to HLVd testing, where a positive infection result also isn’t a symptom.
And I believe the answer to your question is no; it was not a healthy plant based on the definition of health (which means lack of disease, among other points). See my comment earlier in this post:
Not everything is a disease symptom. For example, the negative effect on terpenes from HLVd in hops (or Cannabis) isn’t a symptom.
If a cannabis plant shows no symptoms associated with HLVd, but tests positive for HLVd, and the viroid negatively affects the host’s secondary metabolites, that’s asymptomatic (symptomless) harm.
It’s “latent”
Sometimes it shows up, sometimes it doesn’t. Depends on overall strength of the genetic. Sensitive / delicate varieties always seem to express it first. That and piss poor genetics
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Did mention I went back and read the (1988) paper, and thus recognized that the author was using a different definition of “latent” than I was trained on….
Pointed at the definition I was using…there it is for those what don’t click through
Although many viruses are capable of subclinical infection, only a few are known to undergo true latency. In latent infection, the full viral genome is retained in the host cell, but its expression is dramatically restricted, such that few viral antigens and no viral particles are produced. To qualify as latency, this cryptic form of infection must display two additional properties: persistence and reversibility. Reversibility – i.e. the capacity of the genome to, under the appropriate circumstances, reactivate full viral gene expression, with production of infectious progeny (so-called productive or lytic replication) - is the key requirement of latency. Cryptic states that lack this characteristic are more properly characterized as abortive infections, which typically occur when viruses infect cells that are nonpermissive for viral replication.
(Viral latency and its regulation: lessons from the gammaherpesviruses - PMC)
I did so in response to
Nice of you to repeat, but trust me, I was following along without it.
Not a mistake. It might be wrong, but it’s not a mistake. You may be able to convince me otherwise, but I doubt it.
Imo, if it is caused by the virus, consistently, and you can measure it, calling it other than a “symptom” strikes me as pedantic.
Now that we are looking at shit at the molecular level, we can see more than we once could. Which means “doesn’t have spots on it” is no longer sufficient to call as “asymptotic”.
Is testing positive for the viral genome a symptom? No
Is shedding virus a symptom? No.
Is showing measurable and repeatable transcriptome changes (outside of viral transcripts) a symptom? Not to many folks who were trained last century….and it’s my position that they’re wrong.
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This may seem like an ignorant question but what’s the most long term and economical solution(s).
Quarantine. Screen. Cull. Cultural practices (clean tools).
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dont use aerocloners
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100%. The same goes for RDWC or other recirculating hydroponics like aero, NFT, ebb/flow, etc. Don’t use it if you’re worried about cross-contamination of HLVd between plants.
Dr. Saldi from Tumi Genomics says water is great way to transmit HLVd:
Routes of Transmission for HpLVd? (IG post of her talking on the We the Grower podcast)
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Well that sucks. Everyone not growing in the ground is a type of hydro, imo. Pro mix is just a run to waste system. And if what you are saying is true, then the runoff from one pot should not be allowed to touch another pot. Most tables full of plants that I see look like the runoff from each plant is not separated.
Also, regarding hydro, I wonder if using a sterilizing chemical like pool shock would keep the viroid from spreading through the system.
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yeah i was thinking about that with trays, plants gotta be elevated on the tray
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You did mention you reread a paper but didn’t mention which paper. It’s worth noting that even though HLVd doesn’t have two (or more) infection states, a few plant viroids/viruses do operate in that fashion.
I would be happy to be proven incorrect regarding whether a viroid’s or virus’s effect on secondary metabolites (specifically terpenes and cannabinoids) is a symptom of infection. I hold that it’s not.
I’m afraid I have to disagree that distinguishing between viroid/virus symptoms and effects is pedantic. Words matter. Definitions matter. Bro science pervades our industry partly because of misapplied terms and loosely applied definitions. A great example is hard to kill belief of the mythical trichome covered cannabis calyx, that cannabis flowers are composed of calyces, when that’s completely untrue.
In the context of viruses and viroids:
-
All disease symptoms are effects caused by the pathogen.
-
But not all effects caused by the pathogen are disease symptoms.
I have yet to find a study or academic resource that states or suggests effects on secondary metabolites is a symptom of a viroid or virus diease, nor a diagnostic tool to identify infection. Including those on HLVd in cannabis or hemp published or released in the past decade, let alone in the last century. The reason, I believe, is the term “symptom” in plant pathology has a specific definition, and there are many causes for changes in secondary metabolite production.
To avoid bro science, I think it’s essential we don’t make up definitions or extend accepted definitions without sufficient scientific evidence and reasoning (like if the current definitions are no longer valid).
So, it seems wise for us to defer to accepted terminology and definitions in plant pathology:
Basic Terminology and Definitions in Plant Pathology
Signs and symptoms of plant disease: Is it fungal, viral or bacterial?
From this century:
And although this book is from last century (1978), it’s worth checking out: Symptoms of virus diseases in plants. Specifically the “Pathogenesis” chapter:
- Origin of symptoms
- Absence of symptoms
- Variation of symptoms
- Description of symptoms
The author agrees with you, as do I, regarding improved observation techniques and capabilities beyond visual that would render a previously asymptomatic infection into a symptomatic one. But you and I disagree on whether effects on terpenes and cannabinoids are a symptom of infection.
At the rate we can safely use chlorine without damaging plant roots, I’m unaware if it will deactivate the infectivity of viroids or viruses. Maybe it can, but I haven’t seen data to the point. Because of the damaging effects of chlorine on roots, even at low use rates, I use UV-C to treat irrigation solutions in drain-to-waste systems, so the solution from the batch tank is sterilized before it reaches the plants. I don’t know if UV-C can deactivate viroids/virsuses, but a Google Scholar search should be able to answer that question. UV-C is a must in recirculating systems, IMO.
That’s what I do, too. All coco pots are raised off the trays, and the same goes for Rockwool blocks. I do it primarily to prevent over-watering downstream plants (so they’re not absorbing run-off from upstream plants). But also to reduce the chance of root rot and algae cross-contamination and now, HLVd cross-contamination.
For Rockwool blocks, this next run, I plan to use the Floraflex 6" Floracap, but instead of on top of the block, I plan to place Floracap on the tray and the Rockwool block on the Floracap. Although I want to find something similar at a lower cost:
https://floraflex.com/default/catalog/product/view/id/2150/s/6-floracap-2-0/category/115/
I tried it once long ago for pythium. It turns out that the bacteria live on the roots, so the uvc only zaps what happens to fall off and recirculate.
Do you have any way to tell how much the uvc is doing? There has to be maximum flow rate to get the best effect, too much flow would diminish returns.
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lots of people use these
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The max flow rate depends upon the size of the UV lamp, chamber, and solution turbidity. @danielfp provides target values for UV-C disinfection, and you would ask the supplier of the UV system what flow rates achieve the target values.
He also discusses many other methods of distinction, including chemicals. Aside from UV-C treatment of the batch tank’s solution during irrigation, I plan to test an iodine stock tank. So that I can use it to kill Pythium root rot without affecting the roots (adding it to my nutrient solution).
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