As I concentrate on growing Zephs and Habs from seed in containers, I have found some are more prone to red spot than others, so when repotting those sprinkle cinnamon liberally along each furrow then earth up with soil. As for the Hippeastrums in the garden, I emptied a Parmesan cheese shaker and filled that up with cinnamon. Then I use the biggest hole and sprinkle again liberally over the Hippeastrums about 3 times a year. At the beginning of their growth cycle, at the end and again some time during the winter. And of course have them planted where they are happy. Nothing will stop problems if the plant is not in the right place for it. I bought 5 kilos of cinnamon (I am sure the Indian shopkeeper must have wondered!) and it has lasted me a year or so now, with quite a lot to go. I keep it in an empty 10litre lidded bucket as that is pretty airtight. And when recently I noticed an ants nest at the base of my potted, espaliered lemon tree, gave it a ring around the trunk of cinnamon and the ants nest is no longer there. As I didn't want them farming their "cattle" on the roots of the tree. Ina Crossley Auckland Zone 10a New Zealand