How is that going to have a drying effect, and why would you want to anyway? What information are you working from?

I have read it can cure spear pull by preventing more rot if it begins. I have not checked yet to see if the crown shows signs of rot yet, but didnt know if it could help prevent it even if the spears don't pull out.

I would use it as a preventive measure for sure.

I believe a copper treatment would work as a preventative measure. Have no idea about peroxide and I would not do anything yet if you do not have spear pull.