“yellow leaf spot” or “leaf septoria,” this condition is caused by a fungus that attacks cannabis plants and usually appears in warm, wet weather. The symptoms first appear on the bottom leaves of the plant.
The spots may have darkened borders and may have a hard growth in the middle like a little pimple, but the thing that makes the spots the most unique is they are often very uniform, like little circles. Each spot is the receptacle of a spore which look like tiny dark specks in the center of each spot.
Improve circulation and prune off any infected area. Hope that helps