Looks like an N deficiency to me. The plant as a whole looks on the lighter side of green and the yellowing leaf with the dead tip is another common indicator. Overall, she looks good. Hope you yield some top quality smoke.
In the second picture you see a fungus infection on a couple leaves. The first picture show rust fungus. Notice the round dots that look like rust. That's not nitrogen. You'd see more then that leaf going yellow without the sporadic dots. Plus the fungus is on other leaves.
I am a newb. That sound scary but the rust spot is like dry leaf. Ace hardware soil. Redneck Office trash can pot with holes shot through it. I used Dyna gro 7-9-6 for second 30 days of veg. and it took off. Outside grow. Its been flowering 10 days now. I flushed with one gallon and started using big bud 0-1-3 three days ago and stopped Dyna gro. That's when bottom leaf started turning yellow brown and plant got lighter green. I only see one other bottom leaf wanting to turn a little. (12-12 sun started here about 7 days ago. Average 85 temp and 80 Humidity on cool day). I'm fixin to smoke that yellow leaf here soon, Ill see if its mold and makes me cough. Should I add a little dyna gro 7-9-6 tomorrow feeding instead of only big bud 0-1-3? (Seems like its hungry for it but Im afraid of getting too tall down the road). Above new pic is yesterday progress of flower so far.
Why would you flush going into flower? Yes add some dyna-gro 7-9-6. Regardless of what you've been told you still need nitrogen even in flower.
I didn't know what I was doing and had an overload of information online. (Plant does not take a break while I research) I read the whole grow bible in one night also. I thought when I started big bud nutes 2nd week of flower that I needed to get rid of veg nutes. With yalls help I concluded N & P deficiency. I gave it veg nutes this morning. dyna-gro 7-9-6 at half recommended dose in rain water. Today, the problem was moving up the plant with couple leaf tips turning on lower leaf. I think it was an N and P deficiency. Plant went from min 1 to 3 inch a day growth to not growing much in last couple days. Im thinking I should now go ahead feed half dose 7-9-6 till end of first month flower. Half dose mixed in rain water makes is 3.5-4.5-3 % NPK in my math unless I'm missing something. (My number one Objective is to get high THC and very stinky. It hardly smell's though)
