what to use for mildew during storage.

[bigeasy1]

Can anyone recommend the best mold and mildew repellent for boats stored under shrink wrap from October to late April.(northern climate,NY.)
Every spring I find mold spots on the inner surfaces of my canvas work.It even rotted some of the thread and I had to have it restitched.The top is made from sunbrella supreme that has a vinyl inner layer.
I bought some fabric safe mold remover from 3M that did a great job,and followed it up with some treatment that you apply,which is supposed to prevent further mold growth.I did it this summer and so far no mold,but I guess time will tell when spring rolls around.

Are the hanging mold/mildew repellent things any good.?They claim to have a chemical that permeates the air and stops mold. Any thoughts? Thanks all