Certified GKH Gardening Expert
There is a recipe that I like to use for both preventative, and spot treatments. It is one of the best I have found. You don't have to have all ingredients, but the more you have, the better it works
:First, you will want to prime the ground with dolomitic lime, then spread wettable sulfur to Kill off any infection in the soil. I Also like to spray the plant itself. Mix a few drops of one or more of these ingredients into warm water with a spoonful of coconut oil: Rosemary oil, lavender oil, neem oil, garlic oil, cinnamon extract/oil and for really bad cases, also add clove oil.