Black Stuff On Leaves

So I have two Skunk X Afghan clones in my Portland back yard. Both are otherwise looking good and seem healthy, but one is getting this black discoloration on many leaves. Any ideas what is happening?

Some sort of mite attack ?

I sure hope not

Have you supplied calcium and magnesium to the soil? Has it rained a lot lately?

thegreensurfer said:

Have you supplied calcium and magnesium to the soil? Has it rained a lot lately?

Click to expand...

No. And yes.
Maybe I should get some Botanicare Cal Mag?

Yea get some powdered dolomite lime or the CalMag.
If you had a good amount of rain it can leach ca and mg from the soil.