diseases_knowledge_base/pepper/root_rot.json

{
  "schema_version": "1.0.0",
  "disease_id": "pepper.unknown.root_rot",
  "aliases": [
    "damping-off",
    "Phytophthora root rot",
    "Pythium root rot",
    "Fusarium crown and root rot"
  ],
  "crop": {
    "common_name": "pepper",
    "scientific_name": "Capsicum annuum",
    "family": "Solanaceae"
  },
  "condition": {
    "common_name": "root rot",
    "scientific_name": null,
    "alt_names": [
      "damping-off",
      "crown rot",
      "water mold"
    ],
    "pathogen": {
      "type": "fungal-like",
      "taxonomy": {
        "kingdom": "",
        "phylum": "",
        "class": "",
        "order": "",
        "family": "",
        "genus": "",
        "species": ""
      }
    }
  },
  "issue_type": "unknown",
  "transmission": {
    "vectors": [
      "fungus gnats",
      "shore flies"
    ],
    "dispersal": [
      "contaminated soil",
      "splashing water",
      "infected transplants",
      "contaminated tools and equipment"
    ],
    "overwintering": [
      "in soil as dormant spores (oospores, chlamydospores)",
      "on infected plant debris"
    ]
  },
  "environmental_risk": {
    "risk_factors": [
      "poorly drained or compacted soil",
      "overwatering or excessive rainfall",
      "low soil oxygen",
      "high soil salinity",
      "warm soil temperatures"
    ],
    "temp_c_day": [
      24,
      32
    ],
    "temp_c_night": [
      20,
      26
    ],
    "relative_humidity_pct": [
      80,
      100
    ],
    "leaf_wetness_hours_threshold": 0
  },
  "severity_rubric": {
    "unit": "qualitative",
    "mild": "Slight stunting or yellowing of lower leaves. Plant may wilt during the hottest part of the day but recovers at night.",
    "moderate": "Noticeable stunting. Persistent wilting of lower and mid-canopy leaves. Some leaf drop may occur.",
    "severe": "Plant is severely stunted or dead. Widespread, permanent wilting. Stem may be girdled at the soil line. Plant easily pulled from the ground.",
    "notes": "Severity is assessed on the whole-plant level, focusing on the extent of wilting, stunting, and plant collapse. Root examination is required for definitive diagnosis."
  },
  "symptoms": {
    "leaves": [
      "Lower leaves turn yellow (chlorosis), then brown",
      "Leaves wilt, starting from the bottom of the plant",
      "Wilting occurs even when soil is moist",
      "Premature leaf drop"
    ],
    "stems": [
      "Dark, water-soaked lesion forms at the soil line",
      "Stem becomes constricted, girdled, or 'wiry' at the base",
      "Internal vascular tissue may show brown discoloration when cut"
    ],
    "fruit": [
      "Fruit may be small, shriveled, or fail to develop"
    ],
    "roots": [
      "Roots appear brown, soft, and water-soaked (mushy)",
      "The outer layer (cortex) of the root sloughs off easily, leaving the inner core",
      "Significant reduction in root mass"
    ],
    "whole_plant": [
      "Stunted growth compared to healthy plants",
      "Sudden wilting and rapid death of the plant",
      "Seedlings collapse at the soil line (damping-off)"
    ],
    "signs_microscopic_or_visible": [
      "White, cottony mold (mycelium) may be visible on the stem base or soil surface in highly saturated conditions"
    ]
  },
  "lookalikes": [
    {
      "condition_name": "blight",
      "condition_id": "pepper.fungal-like.blight",
      "key_differences": [
        "Blight often causes large, dark lesions on leaves and upper stems, not just at the soil line.",
        "Blight can directly infect and cause large, sunken, rotten spots on the fruit itself.",
        "With root rot, the primary symptom is bottom-up wilting due to root decay; blight can cause rapid collapse from infections anywhere on the plant.",
        "In early blight infection, the root system may appear healthy, whereas it is the first part affected by root rot."
      ]
    },
    {
      "condition_name": "virus",
      "condition_id": "pepper.viral.virus",
      "key_differences": [
        "Virus symptoms frequently include mosaic patterns, mottling, leaf distortion, or distinct ring spots, which are absent in root rot.",
        "Wilting from a virus (e.g., TSWV) can be one-sided (unilateral) or accompanied by necrotic stem streaks, but the roots are not soft and decayed.",
        "Root rot does not cause the malformed, curled, or stunted new growth characteristic of many viral infections."
      ]
    }
  ],
  "management": {
    "cultural": [
      "Ensure good soil drainage; use raised beds in heavy soils",
      "Avoid overwatering and allow soil surface to dry between irrigations",
      "Rotate crops with non-susceptible families (e.g., grasses, legumes)",
      "Use certified disease-free transplants and seeds",
      "Sanitize all tools, containers, and greenhouse surfaces between plantings"
    ],
    "biological": [
      "Incorporate high-quality compost to improve soil structure and promote beneficial microbes",
      "Apply commercially available bio-fungicides containing *Trichoderma* or *Bacillus subtilis* to the soil"
    ],
    "chemical": [
      "Apply preventative fungicides (e.g., mefenoxam, propamocarb, phosphites) as a soil drench at planting or transplanting",
      "Consider pre-plant soil fumigation in fields with a history of severe disease pressure"
    ],
    "notes": "Preventative measures, especially water management and soil health, are key. Chemical treatments are most effective when applied before symptoms appear and are often not curative on severely infected plants."
  }
}