Seedling Rot in Plumeria: Causes, Symptoms, and Management

Seedling rot, encompassing root and stem rot conditions, is a major impediment to successful plumeria propagation. It results from soilborne pathogens attacking tender seedling tissues, causing decay that undermines plant stability and nutrient uptake.

Causes of Seedling Rot

• Fungal Pathogens: Pythium, Phytophthora, Fusarium, and Rhizoctonia are the primary fungal culprits.
• Bacterial Pathogens: Opportunistic bacteria can cause soft, wet rot, often following fungal infection or physical injury.
• Environmental Conditions: Overwatering, poor soil drainage, and high humidity facilitate pathogen establishment and progression.

Symptoms of Seedling Rot

• Brown, mushy, or water-soaked roots and lower stems.
• Seedlings wilt despite adequate watering, showing poor vigor.
• Seedlings topple over due to weakened root systems.
• Soil near seedlings may emit a foul or sour smell in bacterial rot cases.
• Aboveground parts may yellow, become chlorotic, and fail to thrive.

Disease Progression

• Rot typically begins at the root tips or stem base, spreading upward and outward.
• Tissue breakdown leads to impaired water and nutrient transport, resulting in systemic plant stress.

Management and Prevention

• Use well-draining, pathogen-free soil mixes to minimize inoculum.
• Avoid excessive watering; keep soil moist but not saturated.
• Improve airflow around seedlings to reduce humidity.
• Apply fungicides or bactericides targeted at root and stem pathogens when necessary.
• Remove affected seedlings promptly to limit disease spread.