Coconut Wilt

Causal Organism:

• Commonly associated with Phytoplasma (Root (wilt) disease)
• Also linked to Fusarium spp. and other soil-borne fungi

Symptoms

• Early Stage: Yellowing and flaccidity of older leaves. Drooping of leaflets, giving a wilted appearance.
• Advanced Stage: Shedding of nuts at all stages of development. Reduction in the size and number of nuts. Gradual decline in tree health, leading to death over several years.
• Roots: Extensive root decay, leading to poor nutrient and water uptake.

Mode of Spread and Survival

• The disease spreads through infected planting material.
• Leafhoppers are potential vectors of the phytoplasma.
• Soil-borne fungi can persist in the soil and infect new plants.

Management

1. Cultural Practices: Use disease-free planting materials from certified sources. Maintain optimal spacing and proper irrigation practices. Regular application of organic manures to enhance soil health.
2. Sanitation: Removal and destruction of severely affected palms to prevent disease spread.
3. Chemical Control: Soil drenching with Copper oxychloride (0.3%) or Mancozeb (0.2%) to manage fungal pathogens.
4. Biological Control: Application of Trichoderma viride or Pseudomonas fluorescens to improve root health and suppress soil-borne pathogens.
5. Resistant Varieties: Planting resistant varieties like Chowghat Green Dwarf (CGD) is recommended in affected areas.

Bud Rot of Coconut

Causal Organism:

• Phytophthora palmivora (most common)
• Also caused by Fusarium spp. in some regions

Symptoms

• Initial Stage: Yellowing and wilting of the youngest leaf. Browning and water-soaked appearance at the base of young leaves.
• Advanced Stage: Rotting of the bud (growing point) leading to a foul smell. Leaves easily pull out due to decayed base. Eventually, the entire crown falls off, leading to the death of the palm.
• Fruit and Inflorescence: Immature nut fall and rotting of inflorescence in advanced cases.

Mode of Spread and Survival

• Spread through water splashes, rain, and wind.
• Spores can survive in soil and infected plant debris.
• High humidity and prolonged wet conditions favor disease development.

Management

1. Cultural Practices: Ensure proper drainage to avoid waterlogging. Maintain adequate spacing to promote air circulation. Avoid mechanical injury to the bud during cultural operations.
2. Sanitation: Remove and destroy infected tissues to prevent pathogen spread.
3. Chemical Control:
   • Fungicidal Application:
     • Apply Bordeaux paste (10%) or Copper oxychloride (0.3%) on the infected bud area.
     • Spray Metalaxyl + Mancozeb (0.25%) on the crown region during monsoon seasons.
4. Preventive Measures: Spray preventive fungicides during the rainy season to reduce infection risk. Avoid planting susceptible varieties in disease-prone areas.
5. Integrated Disease Management (IDM): Combine cultural, chemical, and biological control methods. Regular monitoring and early detection are crucial for effective management.