These often get started on their leaves, and if severe, can reduce bulb growth and yield. Downy mildew, which appears as yellow patches and stunts growth, can be controlled by improving air circulation and, if necessary, applying copper-based fungicides. · there is no method of treating diseases of onion , and you cant reverse the damage. Onions are prone to several different diseases , especially in wet growing seasons. · however, we have compiled 6 of the commonest diseases that occur in onion farms around the world including additional information on how to manage and control the diseases. The guide ofers descriptions and photographs of the more common global onion and leek diseases and disorders, including the common name, causal agent, distribution, symptoms, conditions for disease development and control measures. Discover all the onion diseases , key symptoms, and the best prevention and treatment methods for a healthy harvest. The best course of action is to focus on next years crop so that it doesnt happen again. · onions are vulnerable to several diseases , each requiring specific management strategies.
