Mix together a solution of 1 tbsp. baking soda, 2. 5 tbsp. vegetable oil, 1 tsp. liquid soap, and 1 gallon water. Be sure to use liquid soap, not detergent. Since this may potentially burn your leaves, spray a small test area with the solution before spraying the entire plant. If burning is absent or minimal, spray the leaves once every two weeks. [5] X Research source Combine 1-part dairy milk to 2-parts water. Spray the leaves once each week. (Sorry, vegans; non-dairy milk substitutes won’t work). [6] X Research source Spray the leaves with neem oil once every two weeks. [7] X Research source Use fungicides as a last resort if the disease returns for multiple growing seasons. Follow their directions regarding applications. Apply them early, before outbreaks or at the first sign of spots, since they are preventative in nature. Choose organic products if possible for both the plant’s health as well as pollinating insects. [8] X Research source
Do not add infected leaves to compost, since the disease may survive and infect other plants when that compost is used as mulch.
Pruning the lower canopy is also safer – you won’t need to get to those high-up branches.
Cover the soil around newly planted areas with mulch. This will absorb water and keep the disease from splashing up into the leaves when it rains.
Also adjust any lawn sprinklers so they don’t soak your leaves unnecessarily.
