Powdery mildew
Podosphaera tridactyla
What is Powdery mildew (Podosphaera tridactyla)?
Powdery mildew (Podosphaera tridactyla) is a fungal disease that affects various plants worldwide. Commonly affected plants include plums, peaches grapes, cucumbers, roses, and others. It manifests as white or gray powdery growth on leaves, stems, flowers, and fruits. Common symptoms include circular patches of white fungal growth on fruit in spring, which later become scabby and dry. It occurs worldwide and can be found in various regions and climates.
How does Powdery mildew (Podosphaera tridactyla) occur?
Erysiphe cichoracearum survives winter as spore-forming structures called cleistothecia on shoots, leaves, and bark. In spring, spores are released and spread by wind, water, or insects. They infect susceptible plants like plum trees, forming a white, powdery coating. The fungus grows, reproduces, and spreads the infection to other plants. It can also overwinter on plant debris or dormant buds.
Symptoms
1 - Impact on Plants
Powdery mildew weakens plants, making them vulnerable to pests and diseases. It stunts growth, reduces fruit production, and lowers overall yield. Severe infection can lead to nutrient deficiencies. Furthermore, it can block sunlight on infected leaves, disrupting photosynthesis.
3 - Impact on Soil
Powdery mildew disrupts beneficial soil microorganisms, affecting nutrient cycling and overall soil health. Podosphaera tridactyla spreads and impacts nearby plants and ecosystems.
Solutions
2 - Prevention and Cultural Controls
• Choose powdery mildew-resistant plant varieties. • Ensure proper spacing between plants for good airflow. • Position plants in sunny areas to discourage powdery mildew development. • Water plants at the base to keep foliage dry, avoiding overhead watering. • Remove and dispose of infected plant parts promptly. • Prune dense foliage to improve airflow and reduce humidity. • Practice good garden hygiene by cleaning up plant debris and fallen leaves. • Monitor plants regularly for early signs of powdery mildew.
3 - Chemical Control
• Available fungicides for powdery mildew control include propiconazole (Orbit, Bumper), thiophanate methyl (Topsin-M), pyraclostrobin/boscalid (Pristine), myclobutanil (Rally), sulfur dust, wettable sulfur, and liquid lime sulfur. • These fungicides have different modes of action and application rates. It is important to follow label instructions, including any restrictions on specific crops.
