Onion Downy Mildew: Symptoms, Control & Best Treatment Tips

Downy mildew, caused by the pathogen Peronospora destructor, is a serious disease affecting onion crops worldwide. It thrives in cool, damp conditions, making it a significant problem during specific seasons or in poorly drained fields. Understanding its lifecycle and symptoms is crucial for effective management.

Symptoms of Onion Downy Mildew

• Leaf Discoloration: Leaves turn pale green, then yellow, and eventually collapse.
• Oval-Shaped Lesions: Violet or purple lesions appear on leaves.
• Severe Infections: Can lead to bulb rot, making the crop unmarketable.
• Bulb Damage: Infected bulbs may shrivel or sprout prematurely. In storage, systemic infections can cause bulbs to become soft and watery.

Onion Downy Mildew Control Strategies

1. Cultural Practices

• Crop Rotation: Avoid planting onions in the same field for consecutive seasons.
• Resistant Varieties: Choose mildew-resistant onion varieties to reduce infection risk.
• Proper Drainage: Ensure good water management to lower humidity around plants.
• Sanitation: Remove and destroy infected plant debris after harvest to prevent disease spread.

2. Chemical Control

Frequently Asked Questions (FAQs)

Q. What is downy mildew in onions?

A. Downy mildew is a fungal-like disease (Peronospora destructor) that causes yellowing, lesions, and bulb rot in onions.

Q. How can downy mildew be prevented?

A. Preventive measures include crop rotation, using resistant varieties, maintaining good drainage, and applying fungicides when needed.

Q. Can downy mildew spread through onion seeds?

A. Yes, the pathogen can infect seed stalks and flower parts, making seeds a potential source of infection.

Q. Does weather affect downy mildew development?

A. Yes, cool and humid conditions (10-18°C, 85%+ humidity) favor the development and spread of downy mildew.

Written by :- Nitika Chourasiya, Agristudent