Cercospora leaf spot is a common fungal disease of okra (Abelmoschus esculentus) caused by Cercospora malayensis and C. abelmoschi. These pathogens thrive in humid and wet conditions, leading to severe defoliation and yield losses. Below is an overview of the disease's symptoms, contributing factors, and management strategies.

Symptoms

1. Types of Spots:

   • Cercospora malayensis: Small, brown irregular spots surrounded by red or pink borders.
   • Cercospora abelmoschi: Sooty black, angular spots.

2. Progression:

   • Symptoms start on older, lower leaves and gradually spread to younger, upper leaves.
   • Leaf spots enlarge, coalesce, and cover the entire leaf, leading to necrosis.
   • Necrotic leaves may roll and dry but remain attached to the plant.

3. Impact on Plant:

   • Severe defoliation weakens the plant, reducing photosynthesis and ultimately yield.

Contributing Factors

1. Environmental Conditions:

   • High humidity, rainfall, and warm temperatures favor disease development.
   • Overhead irrigation (sprinklers) creates a microclimate conducive to pathogen multiplication.

2. Spread of Pathogen:

   • Rain splash and wind aid in spreading fungal spores (conidia) within and between fields.
   • Infected seedlings, human activity, and animal movement also contribute to disease spread.

Management Strategies

1. Cultural Practices:

   • Avoid overhead irrigation to reduce leaf wetness.
   • Ensure adequate spacing between plants to improve air circulation.

2. Crop Sanitation:

   • Remove and destroy infected plant debris to reduce inoculum.
   • Use disease-free seedlings for planting.

3. Fungicide Application:

   • Apply appropriate fungicides during early infection stages, especially during humid seasons.

4. Resistant Varieties:

   • Cultivate okra varieties resistant to Cercospora leaf spot when available.

5. Field Hygiene:

   • Minimize human and animal movement within infected fields.

Key Takeaway: Effective management of Cercospora leaf spot in okra requires a combination of good cultural practices, timely fungicide application, and field sanitation to curb the spread of the disease and protect yields.