Sunflower Downy Mildew: Fungal Disease and Management Strategies

Downy mildew is a serious disease that can affect sunflowers, caused by the oomycete fungus Plasmopara halstedii. It can cause significant yield losses, particularly in cool, wet conditions. The fungus survives the winter in soil as oospores. In the spring, when soil conditions are warm and moist, the oospores germinate and release zoospores. Zoospores are attracted to the roots of young sunflower plants and infect them. Once inside the plant, the fungus grows and spreads throughout the plant, causing the characteristic symptoms of downy mildew.

• Type of Infestation: Fungal Disease 
• Common Name: Downy Mildew
• Causal Organism: Plasmopara halstedii
• Affected Parts Of the plant: Leaves and Stem

Environmental favorable factors for pests/Diseases:

• Temperature: Downy mildew thrives in cool weather, typically with air temperatures between 10°C and 15°C (50°F and 59°F).
• Humidity: High relative humidity is crucial for the development and spread of the fungal spores.

Symptoms of Pest/Disease:

• Yellow and Brown Spots on the upper surface of the leaves.
• White, Gray or Bluish downy growth on the underside of leaves.
• Stunted growth
• Wilting of leaves
• Fruit Drop

 Measures to control Pests/Diseases:

Products	Technical Names	Dosages
META MANCO	Metalaxyl 8 % + Mancozeb 64 % wp	1.5 to 2 kg per ha
DR BLIGHT	Metalaxyl-M 3.3% + Chlorothalonil 33.1% SC	300-400 ml/acre
AZOXY	Azoxystrobin 23 % sc	200 ml/acre
METAXEL	Metalaxyl 35 % ws	150-300 ml per Acre