rust spots on leaves

It’s my first grow And my girls were doing great, till today I noticed some dark brown line’s and spots.. any help would be appreciated

Hey guys been a while since I've posted. I recently have taken my first swing at this beautiful art. But it's hardly art to start with lol. So I've been running three purple punch autos of two different ages one in 15l smart pot in canna terra seed mix soil(which someone found out fir me should...

Hi, I am not overly concerned with these spots but being new to growing cannabis it would be good to learn from it. Plant is really healthy besides these three leaves. I am thinking maybe the start of calcium deficiency? The plant is on its 57th day from sprouting in Pro-Mix soil. Re-potted...