Downy mildew is a fungal disease that affects a variety of plants, particularly those in the grape and vegetable families. It thrives in warm, moist conditions and can cause yellowing leaves, stunted growth, and reduced yields. The disease is often identified by a fuzzy, grayish or white growth on the undersides of leaves. Controlling downy mildew involves proper plant spacing for air circulation, regular monitoring for symptoms, and applying fungicides when necessary. Good cultural practices, such as avoiding overhead watering, can also help reduce the risk of infection and promote healthier plants.