Oidium sp. and Leveillula taurica

Fungal Disease

Oidium sp. and Leveillula taurica

Fungal Disease

Powdery mildew, caused by Oidium sp. and Leveillula taurica, is a common fungal disease affecting marigolds. It primarily appears as a white, powdery growth on the aerial parts of the plant. This disease can hinder plant growth, reduce flowering, and diminish plant aesthetics. Here’s a detailed look into the disease and how to manage it.

1. Causal Organisms

• Oidium sp. and Leveillula taurica are responsible for causing powdery mildew in marigold.
• These fungi thrive under specific temperature and humidity conditions, making environmental management critical.

2. Symptoms

• A whitish, powdery growth forms on leaves, stems, and flowers.
• The infection reduces the plant's vigor, affects flowering, and can lead to defoliation in severe cases.

3. Favorable Conditions for the Pathogen

• Leveillula taurica: Optimal spore germination occurs at 25°C and 85% relative humidity. It thrives best between 20-30°C and 75-95% humidity, while temperatures above 30°C or humidity levels outside 75-95% are unfavorable for its growth.
• Oidium sp.: Germinates best at 15-26°C and relative humidity between 75-98%. High humidity favors spore germination, but excessive humidity can hinder mycelial development.

4. Management

• Cultural Practices: Avoid overcrowding plants to promote airflow, and avoid overhead watering that can create humid conditions.
• Fungicide Use: Early detection and fungicidal sprays can help control the disease. It’s important to follow recommended guidelines to prevent resistance development.

Proper management of humidity and temperature is key to preventing powdery mildew, ensuring healthier marigold crops.