Powdery Mildew in Capsicum: Causes, Symptoms, and Control

1. Cause

• The disease is caused by the fungus Leveillula taurica (synonyms: Oidiopsis taurica, Oidiopsis sicula).
• Is more prevalent in warm, semi-arid climates.
• The fungus has a broad range of host plants, including various crops and weeds, which enable it to overwinter.
• Temperatures below 30 DC favor infection, while higher temperatures accelerate symptom development.
• Cool nights facilitate infection in regions with high daytime temperatures.

2. Symptoms

• Light-green to bright-yellow irregular blotches appear on the upper surface of older leaves.
• As the disease progresses, lesion centers turn necrotic.
• Younger leaves remain unaffected until they mature.
• Infected leaves droop and curl upwards along the edges.
• Severely affected leaves shrivel, dry, and fall off.
• In extreme cases, defoliation can cause sunburn on fruits.
• White, powdery fungal growth appears predominantly on the lower side of leaves, where it sporulates profusely.

3. Cultural Control

• In many cases, the disease does not require control measures.
• Regular monitoring of capsicum plants can help detect early infections.
• Remove and destroy infected plant parts to reduce fungal spread.
• Maintain adequate plant spacing to promote airflow and reduce humidity.
• Avoid excessive nitrogen fertilization, which can make plants more susceptible to infection.

4. Chemical Control

• If infection is severe, apply recommended fungicides such as sulfur-based or systemic fungicides like triazoles and strobilurins.
• Always follow the label instructions for dosage and application frequency.
• Rotate fungicides with different modes of action to prevent resistance buildup in the pathogen population.

5. Conclusion

• Powdery mildew in capsicum can cause significant yield losses if left unchecked.
• Early detection, cultural practices, and judicious fungicide use can effectively manage the disease.
• Farmers should adopt an integrated disease management approach to ensure healthy plant growth and productivity.