Crop Rotation: Rotate onions and other Allium crops with non-host plants for at least three years to help break the disease cycle and reduce the pathogen's population in the soil.
Proper Plant Spacing: Provide adequate spacing between onion plants to promote good airflow and reduce leaf wetness. This can help minimize favorable conditions for disease development.
Avoid Overhead Irrigation: Use drip irrigation or other irrigation methods that minimize leaf wetness. Overhead irrigation can create a moist environment that encourages downy mildew spread.
Remove Infected Plant Material: Promptly remove and destroy any infected plant material, including infected leaves and bulbs. Proper disposal helps prevent the spread of the disease.
Fungicide Applications: Fungicides labeled for downy mildew control can be applied preventively or as soon as symptoms are observed. Consult with local agricultural extension services or experts for recommended fungicides and appropriate application timings. Follow the instructions on the fungicide label regarding rates, safety precautions, and pre-harvest intervals.
Resistant Varieties: Consider planting onion varieties that have some level of resistance to downy mildew. Resistant varieties can help reduce the severity of the disease.