That sounds like a good recipe for cleaning floors, but I don't think I'd use that much bleach on a plant. You would sterilze countertops and dishes with that much bleach. oh, it might be a good proportion for sterilizing bypass pruners when you're trimming off diseased rose canes.

But there are much less poisonous recipes for powdery mildew and blackspot. Check the FAQ's for good and truely organic recipes for combating those diseases. Cheryl

Bleach is pretty potent stuff to use in the garden, a 1 part bleach to 10 parts water solution is used as a major disinfectant in hospitals, resturants, and many other places. It is what is used to clean up body fluids after an accident. A 50/50 solution of fat free milk and water works wonders, or 1 teaspoon baking soda in 1 quart of water sprayed every 5 to 7 days if there is an active Black Spot or Powdery Mildew presence, or every 7 to 10 days to keep that from occurng.