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| virology:b:bipolaris [2026/07/03 00:52] – hide inline confidence from public + ensure auto-gen banner clonebot | virology:b:bipolaris [2026/08/23 21:52] (current) – vaugith |
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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.// | ====== Bipolaris ====== |
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| ====== Bipolaris (Bipolaris cactivora tip rot) ======Â | **Examples of early stage:**Â |
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| | **Examples of late stage:**Â |
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| ===== Description ===== | ===== Description ===== |
| Bipolaris tip rot is a highly destructive fungal disease caused by the pathogen //Bipolaris cactivora// that primarily targets the growing tips (apices) of Trichocereus cacti. Â | Bipolaris manifests physically at the tip of columns in the following stages:Â |
|  | * **Initial Stage:** When it first presents, the epidermis color of the affected area turns deep purple without a raised blister, and can have weeping black ooze. |
| The disease manifests physically at the apex of the plant:Â | * **Progression:** As the infection runs its course or dries out, the affected tissue turns deep black, crusts over, and begins to sporulate. Â |
| * **Initial Stage:** It presents as a wet, "black goopy mess" (often referred to as "weeping black rot"). The epidermis color of the affected area transitions from healthy green or glaucous blue to a deep purple, and eventually to a dark, necrotic black. | * **Growth Arrest:** The tip is typically destroyed or severely damaged, leading to a terminated tip. If the plant survives, it walls off the infection, resulting in a scarred apex from which pups may eventually emerge, or not. |
| * **Progression:** As the infection runs its course or dries out, the affected tissue turns grey, crusts over, and begins to sporulate. Â | |
| * **Growth Arrest:** The rib structure at the tip is typically destroyed or severely distorted, leading to arrested growth. If the plant survives, it walls off the infection, resulting in a scarred, grey apex from which new ribs and growth tips (offsets) eventually emerge. | |
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| =====Origin ===== | =====Origin ===== |
| Bipolaris tip rot is caused by the fungal pathogen //Bipolaris cactivora//. Outbreaks are heavily associated with seasonal transitions, high rainfall, and sudden cold snaps. It is often confused with other top-down fungal pathogens like //Fusarium proliferatum// and //Neocosmospora//, or bacterial wet rot (such as //Erwinia carotovora//). | Bipolaris is caused by the fungal pathogen //Bipolaris cactivora//. It is active in warm, humid summer weather with cycles of wet and dry soil. Outbreaks are also associated with seasonal transitions, high rainfall, and sudden cold snaps. It is often confused with other top-down fungal pathogens like //Fusarium proliferatum// and //Neocosmospora//, or bacterial wet rot (such as //Erwinia carotovora//). |
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| ===== Cultivation Notes ===== | ===== Cultivation Notes ===== |
| * **Environmental Management:** Avoid excessive watering during cold snaps and seasonal transitions. Protect plants from freezing temperatures, which cause cells to expand and burst, creating entry points for the fungus. Raising the soil line or mounding can help prevent wet roots. | * **Environmental Management:** Avoid excessive watering during cold snaps and seasonal transitions.  |
| * **Soil & Nutrition:** Ensure proper soil pH and nutrient balance. Hindered calcium availability (often caused by pH imbalances or excess of other nutrients) can weaken the plant's defenses. Some growers apply dolomite lime (raises soil pH) or gypsum and epsom salts as part of a winter routine. | * **Soil & Nutrition:** Ensure proper soil pH and nutrient balance. Hindered nitrogen, potassium, and calcium availability (often caused by pH imbalances or excess of other nutrients) can weaken the plant's defenses. Some growers apply dolomite lime (raises soil pH) or gypsum and epsom salts as part of a winter routine. |
| * **Chemical Treatment:** | * **Chemical Treatment:** |
| * **Phosphorous Acid (Phos Acid):** Highly recommended as a preventative and active treatment. For active infections, spray directly on the wound. Brad Albert suggests using up to three times the recommended dose for virulent cases, applying repeatedly until the infection dries, crusts, and turns grey. | * **Phosphorous Acid (Phos Acid):** Highly recommended as a preventative and active treatment. For active infections, spray directly on the wound. Some users suggest using up to three times the recommended dose for virulent cases, applying repeatedly until the infection dries, crusts, and turns grey. |
| * **Propiconazole:** Recommended by community authority Gee Bee, though she notes that true Bipolaris may not respond to it, requiring physical removal. Note: Propiconazole is not recommended for edible plants (labeled for turf and ornamentals). | * **Propiconazole:** Recommended by community authority Gee Bee, though she notes that true Bipolaris may not respond to it, requiring physical removal. Note: Propiconazole is not safe for edible plants (labeled for turf and ornamentals). |
| * **Sulfur Powder:** Generally ineffective at stopping systemic or active outbreaks, as the rot may reappear elsewhere. | * **Sulfur Powder:** Generally ineffective at stopping systemic or active outbreaks, as the rot may reappear elsewhere. |
| * **Physical Intervention (Chopping):** If chemical treatments fail or the rot continues to spread down the ribs, cleanly chop the infected tip. Deciding to chop immediately versus "letting it ride" is a common dilemma; some plants successfully throw off the infection and offset naturally, while others will rot entirely if not amputated early. | * **Physical Intervention (Chopping):** If chemical treatments fail or the rot continues to spread down the ribs, cleanly chop the infected tip. Deciding to chop immediately versus "letting it ride" is a common dilemma; some plants successfully throw off the infection and offset naturally, while others will rot entirely if not amputated early. |
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| | <ifauth @trusted_grower,@admin> |
| ===== Community Discussion & Citations ===== | ===== Community Discussion & Citations ===== |
| //The community discussion centers on identifying and treating a severe outbreak of tip rot on Trichocereus cacti. While some members initially misidentified the pathogen as bacterial, the consensus established it as the fungal pathogen Bipolaris cactivora, with community authority Gee Bee noting that Fusarium proliferatum and Neocosmospora present similarly. Treatment strategies are divided between aggressive chemical intervention (using high doses of phosphorous acid or systemic fungicides like propiconazole) and physical amputation ("chopping"). Additionally, growers discussed the role of environmental stressors—such as cold snaps, excessive winter rain, and soil pH/calcium imbalances—as the primary triggers for these outbreaks, while clarifying that pests like mealybugs are likely attracted to the fungal hyphae rather than acting as primary vectors.// | //The community discussion centers on identifying and treating a severe outbreak of tip rot on Trichocereus cacti. While some members initially misidentified the pathogen as bacterial, the consensus established it as the fungal pathogen Bipolaris cactivora, with community authority Gee Bee noting that Fusarium proliferatum and Neocosmospora present similarly. Treatment strategies are divided between aggressive chemical intervention (using high doses of phosphorous acid or systemic fungicides like propiconazole) and physical amputation ("chopping"). Additionally, growers discussed the role of environmental stressors—such as cold snaps, excessive winter rain, and soil pH/calcium imbalances—as the primary triggers for these outbreaks, while clarifying that pests like mealybugs are likely attracted to the fungal hyphae rather than acting as primary vectors.// |
| | 2026-06-22 (approx) | Thomas Mitchell | "the fun of it all brother they have all been fine in the ground for a few years. These few months in Vic been weird. High temps then a few cold snaps mixed in with some rain and then a 22 on Wednesday this week. Cacs are confused haha" | | | 2026-06-22 (approx) | Thomas Mitchell | "the fun of it all brother they have all been fine in the ground for a few years. These few months in Vic been weird. High temps then a few cold snaps mixed in with some rain and then a 22 on Wednesday this week. Cacs are confused haha" | |
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| <ifauth @trusted_grower,@admin> | |
| ===== Contributor Confidence ===== | ===== Contributor Confidence ===== |
| //Visible to trusted reviewers only.// | //Visible to trusted reviewers only.// |
| | Jim Knowlton | 6/10 | | | Jim Knowlton | 6/10 | |
| | Thomas Mitchell | 6/10 | | | Thomas Mitchell | 6/10 | |
| </ifauth> | |
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| * **Wilfy Fletcher:** Active participant who provided detailed greenhouse observations and treatment experiences, accepting correction when necessary. | * **Wilfy Fletcher:** Active participant who provided detailed greenhouse observations and treatment experiences, accepting correction when necessary. |
| * **Peter Maxwell, Hayley Marie, Phil Mack, Jim Knowlton, Thomas Mitchell:** Provided consistent, practical observations regarding environmental triggers, safety warnings for chemical applications, soil amendments, and the physical progression of the disease. | * **Peter Maxwell, Hayley Marie, Phil Mack, Jim Knowlton, Thomas Mitchell:** Provided consistent, practical observations regarding environmental triggers, safety warnings for chemical applications, soil amendments, and the physical progression of the disease. |
| | </ifauth> |
