discoloration yellow tips

These girls have one more week until harvest, I just started flushing today but the sugar leaves appear to have these brown patches around the outside of them. Should I be concerned for anything? Mold, Mildew, or is this just a natural product that I am not aware of in the late stages of...

So, i let pictures do the explaining. Giving nutes have not helped sop far. An all the problems where there before nutes where given. I have all the deficiency tables and stuff so my guess is - potassium deficiency? Too much light? 250w HPS grow light Two plants - Silver Haze #9 and Sin Tra...