So sad....
Being in Canada, perhaps your season was coolish and wet? Hot sunshine is a good preventative of fungal (and related, thanks imafan! ) diseases. The people who live in US south west never have these diseases (but then they have to pour precious water on theirs, instead of having it fall out of the sky).
Now that you have had blight in your garden, you will need to start treating preventatively right away this year, because spores are likely to still be around.