Sorry for the late response. I was really busy last days - my kid's birthday and Orchid Show hosted by our Club, today our Club October meeting and tons of other things going on.
There are different kinds of fungicides. The most common are contact and systemic. Contact fungicides protect plant only locally, if I can say so. I mean it does not go into plant tissues; it protects plant only on the spot where it was applied. Contact fungicides, like Dithane M 45, should be used only if a problem occurs. Systemic fungicides move to different parts of a plant through vessels and can be used also as a preventive "medicine". I've read and I believe it is true that systemic fungicides also protect new growths which appear after treatment.
I never used cinnamon as a component of a solution. I use cinnamon powder to treat cuts or broken\damaged leaves, roots etc.