Powdery mildew
Erysiphe lycopersici
What is Powdery mildew (Erysiphe lycopersici)?
Powdery mildew Erysiphe lycopersici is a fungal disease that affects various plants. It is distributed globally and can infect a wide range of plant species, including vegetables such as tomatoes. The disease appears as powdery white or grayish patches on leaves, stems, flowers, and fruits. Infected plants may show symptoms such as yellowing, distortion, and eventual leaf death. Powdery mildew thrives in warm and dry conditions, with moderate temperatures (60° to 80°F) and high humidity being favorable for its development.
How does Powdery mildew (Erysiphe lycopersici) occur?
Powdery mildew reproduces asexually through airborne spores called conidia. The fungus forms conidia on the surface of its mycelium, which grows on infected plants. When conditions are suitable, the conidia are released into the air and can be carried to new host plants. Upon landing, the conidia germinate and initiate new infections, continuing the cycle. This method of reproduction enables the fungus to quickly spread and infect susceptible plants.
Symptoms
1 - Effects on Plants
Erysiphe lycopersici causes reduced plant vigor, growth, yellowing, wilting, and deformities. Premature leaf drop and defoliation further decrease fruit quality and yield, impacting plant health and economic productivity.
Solutions
1 - Cultural Practices for Prevention
• Choose resistant plant varieties and provide proper spacing for good airflow. • Plant in sunny areas to reduce humidity and create unfavorable conditions for powdery mildew growth. • Avoid overhead watering and irrigate at the base of plants in the morning to keep foliage dry . • Remove and destroy infected plant material promptly to prevent the spread of the disease. • Practice proper fertilization and overall plant health maintenance to enhance resistance.
2 - Fungicide Application and Management
• Opt for least-toxic options such as horticultural Oils like Saf-T-Side Spray Oil and Sunspray Ultra-Fine Spray Oil. • Neem and jojoba oil (e.g., E-rase) has fungicidal properties and can be used to control powdery mildew infections. • Biological fungicides containing beneficial microorganisms like Bacillus subtilis (e.g., Serenade) can help prevent powdery mildew infections. • Wettable sulfur products, such as Safer Garden Fungicide, can be effective for powdery mildew control. • Follow the instructions on the label for proper application timing and rates.
3 - Integrated Management Strategies
• Employ a combination of cultural practices and fungicide applications for an integrated approach. • Rotate susceptible crops to different locations each year to disrupt the disease cycle. • Maintain a clean garden by removing debris and weeds that may harbor powdery mildew. • Regularly inspect plants for early signs of powdery mildew and take immediate action. • Seek guidance from local gardening resources or extension services for region-specific recommendations.
