Rust problem or perhaps mag deficiency?

Hey there. I have started my first grow, and I have run into a couple problems. The ladies are just under 3 weeks old, and all seem to have orange spots and discoloration, particularly on older growth near the bottom of the plants. I recently fixed a fungus gnat issue that resulted from a bad bag of roots from my local hydro store, and this probably has nothing to do with my current problem. Nor is this a spider mite or any other type of bug issue. I have good ventilation, proper humidity levels, not feeding with a lot of ferts atm, just a mild guano and compost tea. This is an example of exactly what I am facing. Any help would be greatly appreciated.

is that a pube on your plant?

It's not my plant, if you read more closely it says this is an "example" of what I am facing. Oh and at the bottom, it says 420 magazine. Now that we have that out of the way, anyone with any sense, experience or intelligence know anything about the problem I have described?