What To Do - About Powdery Mildew

Inevitably more complicated diseases arise. Some of the herbs are demonstrating powdery mildew problem, which I'm to understand should be expected in this climate.

Peppermint

Borage

I don't know too much about dealing with this stuff so am researching online. Meanwhile the fungus is progressing. I could have recognized this problem sooner, although the reason I can't ignore it right now is because it loves moderate humidity, and proliferates under clouds (thanks a lot Seattle summer)

I guess my job as gardener is to figure out how to help the herbs develop stronger resilience to infection. So crowded planting does not help (but there's not enough space!) Also I'm supposed to avoid overhead watering (no drip irrigation plan in the works yet) and remove the plants in the fall to avoid the fungus overwintering. It seems there's little I can do now, since the infection is rampant. Except to ride out the season, and I guess, sing to the plants that are in the most pain.

This website discusses organic fungicide methods like cornmeal and baking soda (I haven't decided yet if I'm going to go that far): http://gardening.about.com/od/gardenproblems/a/PowderyMildew.htm