Cinnamon is used by many orchid growers as an anti-fungal agent. I sprinkle a little on other plants too -- plant roots when dividing or cutting them apart or leaf cuts. I even sprinkle some on the surface of potted plant if you notice ants -- they don't like it and will move. Might need a couple of applications. No need to apply a lot, just a light sprinkle. For my garden I buy the cheaper dollar store jars of cinnamon.
