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| | > ⚙️ **Auto-generated, pending human review.** This page was compiled automatically by a bot from community discussions and has **not yet been verified by an editor**; details may be imperfect and corrections are welcome. //Editors: delete this line once you have reviewed the page.// |
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| ====== Mosaic Virus ====== | ====== Mosaic Virus ====== |
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| ===== Overview ===== | ===== Description ===== |
| Mosaic Virus in cacti refers to a group of viral infections (often suspected to be Tobacco Mosaic Virus/TMV, related Tobamoviruses, or Sammons' Opuntia Virus) that cause distinctive yellow patterning, splotches, or rings on the plant's epidermis. While the virus remains permanently in the plant's sap once infected, it is generally considered non-lethal and often only expresses visible symptoms when the host cactus is subjected to environmental or nutritional stress. Because it is highly contagious through sap transmission, managing the virus is a key concern for growers looking to protect their collections. | Mosaic Virus in *Trichocereus* refers to a group of viral infections that manifest as distinctive chlorotic patterning on the plant's epidermis. The virus does not alter the genetic rib count, spine length, spine color, or the underlying glaucous green color of the host cactus, but it causes localized disruptions in chlorophyll production. |
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| | Symptoms present as light yellow splotches, swirly mosaic-like patterns, crescent moons, empty circles, figure-eight shapes, or concentric rings. These markings typically appear on the flat surfaces of the ribs and near the areoles. In advanced stages, the affected areas can progress to necrotic black and brown scarring and open wounds. The virus remains permanently in the plant's vascular system and sap, though it is often latent and asymptomatic until triggered by external factors. |
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| ===== Symptoms & Identification ===== | ===== History & Origin ===== |
| Identifying Mosaic Virus involves looking for specific markings on the cactus skin, though symptoms can easily be confused with other issues: | The precise origin and introduction of mosaic viruses into *Trichocereus* cultivation remain undocumented. However, there is a strong consensus within the community that these viral pathogens are "pre-loaded" or latent in several historic cultivars. The most notable host is the *Trichocereus pachanoi* clone 'Landfill', alongside a broader suite of established California *pachanoi* clones. The primary suspected pathogens are members of the *Tobamovirus* family (such as Tobacco Mosaic Virus / TMV) or Sammons' Opuntia Virus (Ringspot), the latter of which is historically associated with *Opuntia* species but appears capable of expressing in other cacti genera. |
| * **Visible Signs:** Affected plants display light yellow splotches, "trippy" mosaic-like patterns, crescent moons, empty circles, or figure-eight shapes. In cases resembling Sammons' Opuntia Virus, the markings present as light yellow, often concentric rings. | |
| * **Triggers & Progression:** The virus is frequently latent (or "pre-loaded" in the plant) and only expresses these markings during periods of stress, such as sudden temperature fluctuations, pH changes in the soil, or rapid increases in UV/sunlight exposure. | |
| * **Common Confusions:** | |
| * **Nutrient Issues:** Often confused with nitrogen excess, general nutrient burn, or vitamin/mineral deficiencies (e.g., lack of calcium or magnesium). | |
| * **Fungal Infections:** Can be mistaken for fungal pathogens like Anthracnose or Phoma, which present as spreading splotches or fungal pegs, typically thriving in moist, organic soils. | |
| * **Environmental Damage:** Sun stress (especially after sudden exposure to intense sunlight following overcast periods) and thrips damage can mimic the early stages of viral expression. | |
| * **Variegation:** Sometimes misidentified as natural variegation, though some growers refer to it colloquially as "virus-induced variegation." | |
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| ===== Cause & Spread ===== | ===== Cultivation Notes ===== |
| * **Pathogen:** The primary suspected pathogens are viruses within the *Tobamovirus* family (such as Tobacco Mosaic Virus) or Sammons' Opuntia Virus (Ringspot). | Because there is no known cure for viral infections in cacti, management focuses on minimizing symptom expression and preventing transmission: |
| * **Transmission:** The virus resides permanently in the plant's sap. It is confirmed to spread through grafting. There is also a strong community warning that it can spread via shared water or splashing. | * **Stress Mitigation:** Symptoms are typically triggered by environmental stressors. Growers should avoid sudden transitions in UV exposure (e.g., moving plants directly from overcast conditions to intense summer sun) and provide adequate shade cloth. Protecting plants from extreme temperature fluctuations and sudden soil pH shifts (often caused by heavy rainfall) is also recommended. |
| * **Cultivar Susceptibility:** Certain cultivars, particularly California pachyphytums/pachanois (such as the 'Landfill' clone), are widely reported by growers to carry the virus latently. While Sammons' Opuntia Virus is most common in *Opuntia* species, similar ringspot expressions are observed across other cacti genera. | * **Nutritional Support:** Maintaining a robust fertilization schedule helps the host plant suppress viral replication. A recommended regimen to address potential deficiencies includes top-dressing with granulated gypsum and azomite, supplemented with a balanced 10-10-10 fertilizer, Cal/Mag, fish emulsion, and kelp extract. |
| | * **Biosecurity & Quarantine:** The virus is highly contagious via sap transmission. Infected specimens should be isolated. Growers must avoid sharing water reservoirs or allowing runoff to splash between pots. Tools used for cutting or grafting must be thoroughly sterilized between plants. |
| | * **Differential Diagnosis:** If the symptoms are determined to be fungal (such as Anthracnose or Phoma) rather than viral, the application of phosphorous acid and/or mancozeb is recommended. Sucker bug and thrips damage can also mimic viral patterns; appropriate pest control should be applied if pests are detected. |
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| ===== Treatment & Management ===== | <ifauth @trusted_grower,@admin> |
| There is no known cure for Mosaic Virus; once a cactus is infected, the virus remains a permanent part of its sap. However, the condition can be managed, and symptoms can be minimized: | ===== Community Discussion & Citations ===== |
| * **Stress Reduction:** Keep plants in stable conditions. Providing adequate shade during sudden heatwaves or intense sun transitions helps prevent the virus from expressing. | //Analysis of the discussion.// |
| * **Nutritional Support:** Ensure a balanced feeding regimen to keep the plant's immune system strong. Jesse Joseph Scrabonia recommends top-dressing with granulated gypsum and azomite, followed by watering with a 10-10-10 fertilizer, Cal/Mag, fish emulsion, and kelp extract to resolve potential deficiencies that trigger viral expressions. | |
| * **Quarantine & Hygiene:** Isolate symptomatic plants from the rest of the collection. Avoid sharing water reservoirs or allowing runoff to splash between pots to prevent mechanical transmission of the sap. | |
| * **Diagnostic Testing:** For definitive identification, growers can use commercial testing services (such as Agdia) which offer Tobamovirus screening assays. | |
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| *Note: The community's recognized authority, Gee Bee, did not participate in this discussion.* | ^ Date ^ Speaker ^ Key Insight/Quote ^ |
| | | 2026-01-26 | Chris Carfoot | "yep , looks like it mate" | |
| | | 2026-01-26 | Daryl Lee DeWeese Jr. | "Mine with tmv were a step advanced then that...it would get those then black and brown scarring and wounds" | |
| | | 2026-03-02 | Jesse Joseph Scrabonia | "Looks like vitamin deficiency to me, although it’s does look nearly like TMV. The tell tale sign of TMV are crescent moons and empty circles..." | |
| | | 2026-03-02 | Arik Skromme | "I believe its treated with proper fertilizer, water etc. Healthy plants may not display the tobomovirus. May or may not be TMV either." | |
| | | 2026-04-13 | Kyle Moxie | "That actually looks like Sammons Opuntia Virus (Ringspot)... light yellow, often concentric rings on cactus pads or stems." | |
| | | 2026-04-13 | Oriole Gardens | "Looks like the start of anthracnose imo... or phoma... it's looking fungal." | |
| | | 2026-05-25 | Frits Potgieter | "Mosiac virus, i have a tricho with it, hasn't spread to anything around it in over 7 years... keep it around, most prob wont kill it" | |
| | | 2026-06-08 | Chris Cosby | "I see this in a suite of Cali pachs. It's not just landfill ime. They all carry mosaic viruses and they show up at various times throughout the year for me" | |
| | | 2026-06-08 | Julian Friedman | "Landfill is known for this viral expression, I have a cut of Landfill that is covered in these spots exacerbated by stress, PH changes and temperature fluctuations" | |
| | | 2026-06-08 | Matt Heite | "You have a fungal disease spreading through your seedling tray, most likely through moist organic soil and run off." | |
| | | 2026-06-08 | Nick Fotinakes | "I think landfill is known to have tmv/present splotches like this when stressed." | |
| | | 2026-06-08 | Robby Lapp | "Ok now it has appeared on a couple other cultivars. Predominantly to the south so I am leaning towards it being Sun Stress after being overcast for days and then blasted with Florida (almost summer) Sun." | |
| | | 2026-06-15 | Andrew Vaught | "The issue on your landfill is unrelated - it is an expression of stress, likely from a combination of factors including sudden tempurature and UV increase..." | |
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| ===== Reported Cases ===== | ===== Contributor Confidence ===== |
| //Community examples - the photos above belong to these reporters; credit them.// | //Visible to trusted reviewers only.// |
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| ^ Date ^ Reporter ^ Diagnosed by ^ Confidence ^ Key note / quote ^ | ^ Contributor ^ Confidence ^ |
| | 2026-03-02 | Max Kreitman | Jesse Joseph Scrabonia | 7 | "Looks like vitamin deficiency to me, although it’s does look nearly like TMV. The tell tale sign of TMV are crescent moons and empty circles..." | | | Chris Carfoot | 6/10 | |
| | 2026-04-13 | Aidan Roden | Kyle Moxie | 7 | "That actually looks like Sammons Opuntia Virus (Ringspot)... light yellow, often concentric rings on cactus pads or stems." | | | Daryl Lee DeWeese Jr. | 7/10 | |
| | 2026-05-25 | Benjamin Schwarzschild | Frits Potgieter | 7 | "Mosiac virus, i have a tricho with it, hasn't spread to anything around it in over 7 years... keep it around, most prob wont kill it" | | | Jesse Joseph Scrabonia | 7/10 | |
| | 2026-06-08 | Robby Lapp | Chris Cosby | 8 | "I see this in a suite of Cali pachs. It's not just landfill ime. They all carry mosaic viruses and they show up at various times throughout the year for me" | | | Arik Skromme | 7/10 | |
| | | Kyle Moxie | 7/10 | |
| | | Oriole Gardens | 6/10 | |
| | | Frits Potgieter | 7/10 | |
| | | Chris Cosby | 8/10 | |
| | | Julian Friedman | 7/10 | |
| | | Matt Heite | 7/10 | |
| | | Nick Fotinakes | 6/10 | |
| | | Robby Lapp | 6/10 | |
| | | Andrew Vaught | 7/10 | |
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| ===== Notes & Contradictions ===== | |
| * **Gee Bee's Position:** Gee Bee did not participate in this discussion thread. | |
| * **Viral vs. Fungal/Environmental Disagreement:** There is an ongoing debate regarding whether these splotches are truly viral. While Chris Cosby, Julian Friedman, and others assert that cultivars like 'Landfill' are inherently viral, other experienced growers like Matt Heite and Andrew Vaught argue that similar symptoms are actually fungal expressions (such as Anthracnose or Phoma) triggered by organic soil imbalances, or simple abiotic stress from sudden UV and temperature shifts. | |
| * **Contagion Rate:** Opinions differ on how easily the virus spreads. Frits Potgieter noted that an infected plant did not transmit the virus to neighboring plants over a seven-year period, leading some to believe it only spreads via grafting. However, Kyle Moxie and Chad Rhodes strongly advocate for quarantine, warning that it can spread through shared water. | |
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| ===== References ===== | ===== Credibility Notes ===== |
| * **Contributors:** Chris Cosby, Julian Friedman, Kyle Moxie, Arik Skromme, Jesse Joseph Scrabonia, Frits Potgieter, Robby Lapp, Andrew Vaught, Matt Heite, Oriole Gardens, Chad Rhodes, ScrapGoat Benjamin. | * **Chris Cosby:** Rated highly due to extensive experience with California *pachanoi* cultivars, consistent observations of latent viral expressions, and broad agreement from the community. |
| * **Photo Credits:** Max Kreitman, Aidan Roden, Rá Bee, Benjamin Schwarzschild, Robby Lapp. | * **Andrew Vaught, Matt Heite, & Jesse Joseph Scrabonia:** Provided detailed, diagnostic explanations distinguishing viral symptoms from fungal infections, nutrient deficiencies, and environmental shock. |
| | * **Kyle Moxie & Arik Skromme:** Offered specific botanical and virological context (Sammons' Opuntia Virus, Tobamoviruses) and referenced professional diagnostic testing resources (Agdia). |
| | * **Frits Potgieter & Daryl Lee DeWeese Jr.:** Provided valuable long-term observational data regarding viral progression, transmission rates, and the futility of trying to propagate clean cuttings from infected hosts. |
| | * **Robby Lapp & Chris Carfoot:** Offered direct observations of environmental and pest interactions, though their conclusions regarding nutrient-only causes remain subject to community debate. |
| | * **Oriole Gardens:** Provided a specific alternative fungal diagnosis (anthracnose or phoma) supported by other community members. |
| | * **Nick Fotinakes:** Confirmed the common association of the 'Landfill' clone expressing TMV-like symptoms under stress. |
| | </ifauth> |
