Fungicides for use on Spruce ?

Hello,
I am looking for some sort of fungicide that we can use to treat a spruce spar. There are some deep checks running the length of the spar, and we have found some rot in places. We plan to cut out rotten wood and scarf in new material, but we were interested in maybe applying some chemical to the rest of the spar to kill any spores that may be present. I have heard about boric acid, bleach or vinager being used, but we are looking for detailed proceedings on treating and preventing rot on wooden spars.
What can we do ?
Thanks
Brian