| { |
| "schema_version": "1.0.0", |
| "disease_id": "pepper.disease_fungal.blight", |
| "aliases": [ |
| "Phytophthora blight", |
| "chile wilt", |
| "crown rot" |
| ], |
| "crop": { |
| "common_name": "pepper", |
| "scientific_name": "Capsicum annuum", |
| "family": "Solanaceae" |
| }, |
| "condition": { |
| "common_name": "blight", |
| "scientific_name": "Phytophthora capsici", |
| "alt_names": [ |
| "Phytophthora blight", |
| "Phytophthora root and crown rot" |
| ], |
| "pathogen": { |
| "type": "disease_oomycete", |
| "taxonomy": { |
| "kingdom": "Stramenopila", |
| "phylum": "Oomycota", |
| "class": "Oomycetes", |
| "order": "Peronosporales", |
| "family": "Peronosporaceae", |
| "genus": "Phytophthora", |
| "species": "capsici" |
| } |
| } |
| }, |
| "issue_type": "disease_fungal", |
| "transmission": { |
| "vectors": [ |
| "fungus gnats", |
| "shore flies" |
| ], |
| "dispersal": [ |
| "water splash (rain, irrigation)", |
| "contaminated soil", |
| "infected transplants", |
| "contaminated equipment" |
| ], |
| "overwintering": [ |
| "as oospores in soil", |
| "in infested plant debris" |
| ] |
| }, |
| "environmental_risk": { |
| "risk_factors": [ |
| "poorly drained or heavy clay soils", |
| "standing water after heavy rain or irrigation", |
| "warm, humid weather", |
| "overhead irrigation" |
| ], |
| "temp_c_day": [ |
| 24, |
| 29 |
| ], |
| "temp_c_night": [ |
| 18, |
| 24 |
| ], |
| "relative_humidity_pct": [ |
| 80, |
| 100 |
| ], |
| "leaf_wetness_hours_threshold": 6 |
| }, |
| "severity_rubric": { |
| "unit": "qualitative", |
| "mild": "Localized lesions on a few leaves or a small, non-girdling stem canker. No wilting is present.", |
| "moderate": "Multiple stem cankers, significant leaf blight on several branches, or initial wilting on parts of the plant during the heat of the day.", |
| "severe": "Whole plant is permanently wilted, the main stem is girdled by a dark canker at the crown, and the plant is dead or dying.", |
| "notes": "Severity is based on the progression of systemic infection. Wilting is a key indicator of moderate to severe infection as it signals root and/or crown rot." |
| }, |
| "symptoms": { |
| "leaves": [ |
| "Small, dark green, water-soaked lesions that expand rapidly into large, irregular tan-to-brown patches.", |
| "Affected leaves appear blighted or scalded.", |
| "Leaves may drop, leading to defoliation." |
| ], |
| "stems": [ |
| "Dark brown to black, water-soaked lesions, most commonly at the soil line (crown rot).", |
| "Stem lesions can girdle the stem, causing sudden wilting and collapse of the entire plant.", |
| "Cankers can also form on upper stems and branches, causing dieback above the lesion." |
| ], |
| "fruit": [ |
| "Large, water-soaked lesions develop, which may be covered with a white, powdery or cottony mold (sporangia) in humid conditions.", |
| "Infected fruit shrivels, becomes mummified, and often remains attached to the plant." |
| ], |
| "roots": [ |
| "Root system turns dark brown, becomes soft, and decays.", |
| "Destruction of the taproot and lateral roots leads to poor water and nutrient uptake." |
| ], |
| "whole_plant": [ |
| "Sudden, permanent wilting of the entire plant, often without prior yellowing.", |
| "Stunted growth and rapid plant death, especially in wet, warm conditions." |
| ], |
| "signs_microscopic_or_visible": [ |
| "White, cottony mycelial growth and powdery-looking sporangia on the surface of fruit or stem lesions during periods of high humidity." |
| ] |
| }, |
| "lookalikes": [ |
| { |
| "condition_name": "bacterial_spot", |
| "condition_id": "pepper.disease_bacterial.bacterial_spot", |
| "key_differences": [ |
| "Bacterial spot lesions on leaves are small, angular, and often have a 'shot-hole' look, while blight lesions are large, irregular, and water-soaked.", |
| "Bacterial spot fruit lesions are raised, rough, and scabby, unlike the soft, moldy rot of blight.", |
| "Bacterial spot does not cause the dark, girdling stem cankers at the soil line or the sudden whole-plant wilting characteristic of Phytophthora blight." |
| ] |
| }, |
| { |
| "condition_name": "anthracnose", |
| "condition_id": "pepper.disease_fungal.anthracnose", |
| "key_differences": [ |
| "Anthracnose fruit lesions are distinctly sunken and circular, often with concentric rings and salmon-colored spore masses, whereas blight lesions are water-soaked and covered in white mold.", |
| "Anthracnose does not cause crown rot or sudden, total plant wilting.", |
| "While anthracnose can cause stem lesions, they are typically less aggressive and do not girdle the stem like Phytophthora blight." |
| ] |
| }, |
| { |
| "condition_name": "root_rot", |
| "condition_id": "pepper.disease_fungal.root_rot", |
| "key_differences": [ |
| "While other root rots (e.g., Pythium, Rhizoctonia) cause wilting, Phytophthora blight is distinguished by the prominent, dark brown to black canker at the soil line (crown rot).", |
| "Phytophthora blight also causes aggressive foliar and fruit blight symptoms, which are often absent or less severe with other common root rot pathogens.", |
| "Wilting from Phytophthora blight is often more rapid and complete due to the combination of root rot and stem girdling." |
| ] |
| } |
| ], |
| "management": { |
| "cultural": [ |
| "Plant in well-drained soil, using raised beds to improve drainage.", |
| "Practice careful water management; avoid overwatering and use drip irrigation instead of overhead.", |
| "Implement a crop rotation of at least 3 years with non-host crops (e.g., corn, beans).", |
| "Sanitize all tools, equipment, and stakes to prevent spread.", |
| "Promptly remove and destroy infected plants and surrounding soil." |
| ], |
| "biological": [ |
| "Application of soil-drench bio-fungicides containing beneficial microbes like *Trichoderma* spp. or *Bacillus* spp. can help suppress the pathogen." |
| ], |
| "chemical": [ |
| "Preventative applications of targeted oomycete-specific fungicides (e.g., mefenoxam, metalaxyl, phosphites) as a soil drench or foliar spray.", |
| "Fungicide resistance is a concern; rotate fungicide groups (FRAC codes)." |
| ], |
| "notes": "An integrated approach is essential. Management relies heavily on preventative cultural practices, as chemical treatments are largely ineffective once the plant is severely infected and wilting." |
| } |
| } |
