Organic Gardening - Black Spot

A couple of years ago I had some red tip photinia bushes that developed black spot. I had used a recipe by Howard Garret (the Dirt Doctor) and it worked. I again needed my recipe and this time went on-line to find the remedy. I thought I would give you the link as there were many remedies listed. In the past, the recipe I used was the baking soda mixed with detergent. It was effective and I had the ingredients on hand.