"Aspirin is the remedy for fungal plant problems, Black spot, powdery mildew, and rust are a terrible trio of fungi, which can attack and destroy your plants. Scientists have found that two uncoated aspirin tablets (325 milligrams each) dissolved in 1 quart of water and used as a foliar spray can thwart these diseases."
A tonic for black spot and powdery mildew on roses Roses, while beautiful, are often plagued with black spot or powdery mildew. I mix these ingredients into a tonic, which I spray on my roses: 2 teaspoons of baking soda and 1/2 teaspoon of liquid soap or Murphy's oil soap in 2 quarts of water. The tonic protects the roses for months.
Keep critters away the natural way! Learn about natural insect control for gardens on the Craftsy blog.
Unfortunately, Late blight is not a treatable disease and it will kill your plants. In addition, late blight is highly communicable disease that is carried on wind and will infect other gardens and farms within a 50-mile radius. So it is important to destroy infected plants once you confirm you have late blight and take some preventative measures to stop spores from coming back next year.