Soft Rot of Ginger
Causal Organism: Pythium aphanidermatum, Pythium myriotylum
Symptoms
- Rhizomes:
- Initial water-soaked lesions that turn brown and soft.
- Rotting starts from the tips and progresses inward, leading to a foul odor.
- Infected rhizomes become mushy and disintegrate easily when pressed.
- Shoots and Leaves:
- Yellowing and wilting of leaves starting from the lower leaves and progressing upwards.
- Shoots collapse, and the plant dies prematurely.
- Infected plants can be easily pulled out due to rotting of underground rhizomes and roots.
- Roots: Roots become soft, water-soaked, and eventually rot, disrupting nutrient uptake.
Favorable Conditions for Disease Development
- High soil moisture and waterlogged conditions.
- Warm temperatures (25–30°C).
- Poorly drained soils and high humidity favor rapid disease spread.
Mode of Spread and Survival
- Primary Source: Soil-borne pathogen surviving in infected plant debris and rhizomes.
- Secondary Spread: Through contaminated irrigation water, farm tools, and movement of infected planting material.
- The pathogen can survive in the soil for several years in the absence of a host.
Management
- Cultural Practices:
- Use disease-free, treated rhizomes for planting.
- Ensure well-drained fields with raised beds to prevent waterlogging.
- Rotate crops with cereals or other non-host crops for 2-3 years.
- Avoid continuous cultivation of ginger in the same field.
- Maintain proper spacing to improve air circulation and reduce humidity.
- Soil and Planting Material Treatment:
- Treat seed rhizomes with Metalaxyl-M (3 g/kg) or Mancozeb (3 g/kg) before planting.
- Drench soil with Copper oxychloride (0.3%) or Metalaxyl (0.2%) to control initial infections.
- Apply Trichoderma viride or Pseudomonas fluorescens as a biocontrol agent for soil treatment.
- Chemical Control: Soil drenching with Metalaxyl-M + Mancozeb (0.25%) at 30-day intervals. Use of Copper oxychloride (0.3%) or Fosetyl-Al (0.2%) as preventive sprays.
- Integrated Disease Management (IDM): Combine cultural practices, chemical treatments, and biological controls. Regular monitoring and removal of infected plants to reduce inoculum load.
