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I deliberately omitted lime sulfur because it is extremely dangerous to do, please don't try that at home! First, it has to be done wet not dry. Second the fumes produced generate sulfuric acid inside your lungs when inhaled...very bad news. So, if you want some buy it already prepared from a bonsai supply house. But I still don't recommend it because it is the most caustic fungicide out there and will kill every cell it touches, fungi or otherwise. It's only real use is painting on already dead wood to preserve it on bonsai. If you don't want to use copper (you are correct it can built up with constant use. Mine is a one time problem solving treatment) just use straight lime or straight sulfur.
