I posted this in my local Rocky Mountain GW forum, but realized I probably should have posted here as well:

Can anyone please help me identify this disease? I have four plants in my raised bed garden in Denver, they were growing great until I noticed a few leaves with purple/gray spots. The biggest plants are 6-7' tall already, and I just picked my first few full size tomatoes. Seems to be present mostly on my Big Boy plant. Only a few stems are affected, most look healthy and fine. Any ideas of what it is, and if it can be treated? Thanks!