I just saw your journal entry, even though I'm in a hot/humid/dry climate in the US, we get very wet summers from time to time. I understand your dilemma.

The organic things you can do are to clean up very well in fall, keep picking off the blackspotted leaves, use Seranade (made from a bacteria found in soils with high organic matter) it comes in a concentrate, I hope you can get it in Canada. You can also use the Cornell formula of water baking soda, and a tiny bit of vegetable oil as a sticker-spreader, but I've found that the Seranade works slightly better.

Both of those will need to be used most of the year, starting with that slow warm up in spring when those spores are re-activating; by the time you see blackspot or mildew it's well advanced and you will be hard pressed to get it somewhat under control. You need to keep up with the organic methods until freezing weather comes.

Make sure you have great soil, and add composted horse manure regularly. Some people say adding a layer on top, around your plants, seems to slow weeds down.

Also get your soil tested and add some sulfur; there are two types-the faster one needs to be used with care, and the slower one does take some time. It is found in healthy soils along with calcium, and boron.

Just don't let blackspot or mildew get your roses, or other plants. When those fungi are too thick the leaves can't photosynthesize, and they can't produce the food needed to grow a healthy plant. When the plants are stunted, they have a harder time of getting through the winter. I hope your have a better weather next year, and prettier roses!