Seedborne Diseases in Plumeria: Identification, Prevention, and Management

Growing plumeria from seed offers exciting opportunities for hybridization and cultivar development, but seedborne diseases can pose significant challenges. These diseases are transmitted through infected seeds and can cause seed rot, poor germination, seedling damping-off, and early plant death. Understanding these diseases and implementing effective prevention and management strategies is crucial for successful seed propagation.

Common Seedborne Diseases in Plumeria

1. Fungal Seed Rots and Damping-Off

• Pathogens: Species of Pythium, Phytophthora, Fusarium, and Rhizoctonia are commonly responsible.
• Symptoms: Seeds may fail to germinate or produce weak, rotted seedlings. Seedlings can collapse suddenly due to stem or root rot (damping-off).
• Conditions: High moisture, poor drainage, and contaminated soil or seed surfaces promote disease development.

2. Bacterial Seed Rot

• Pathogens: Various bacterial species can infect seeds, causing soft rot and decay.
• Symptoms: Soft, mushy seed tissues and seedling death shortly after germination.
• Spread: Often through contaminated seed coats or soil.

3. Viral Seedborne Infections

• While rare, certain viruses may be transmitted through seeds, leading to mosaic symptoms, stunted growth, and leaf deformities in seedlings.

Identification and Diagnosis

• Visual Inspection: Seeds with discoloration, soft spots, or abnormal textures may be infected.
• Seedling Symptoms: Poor germination, seedling rot, stem lesions, and leaf abnormalities suggest seedborne disease.
• Laboratory Testing: Seed and seedling tissue analysis can confirm pathogen presence.

Prevention Strategies

Seed Selection and Treatment

• Use certified disease-free seed sources when possible.
• Surface-sterilize seeds before planting using diluted bleach or hydrogen peroxide solutions to reduce pathogen load.
• Soak seeds briefly in hot water treatments following recommended protocols for temperature and duration.

Growing Conditions

• Use sterile, well-draining germination media.
• Avoid overwatering and maintain good air circulation to reduce moisture and pathogen proliferation.
• Plant seeds in clean containers and practice strict hygiene.

Sanitation

• Clean and disinfect all seed starting trays, tools, and work surfaces regularly.
• Remove and destroy infected seedlings promptly to prevent spread.

Management of Infected Seedlings

• Remove and discard symptomatic seedlings to prevent contamination.
• Apply appropriate fungicides or bactericides where approved and necessary for severe outbreaks.
• Adjust cultural practices to improve seedling vigor and resistance.

Summary

Seedborne diseases in plumeria can severely impact propagation success, but can be minimized with careful seed selection, treatment, and growing practices. Vigilance and hygiene in seedling care contribute to healthy, robust plumeria plants.