Please help identify (idiot here)

Neglected my plants in 1 gals for over 2 months. Finally transplanted last week in Happy frog. The older fan leaves on some continuing to die. My conserns are some fungus i don't know. 3 or so had overgrown obvious brown roots when i transpanted. So root rot? Please help identify.Things went relatively well my first 2 grows. Things got busy with my business i failed them. I now know not to neglect these babies whatsoever.

Magnesium deficiency. Give them an Epsom salt foliar feed, in the future add a little lime or gypsum to your potting mix, this shit happens especially if you’re just dialing in a perpetual setup, getting the timing and feed right on veg while waiting for space in flower is a headache but one that’s worth it imo.

On the verge of a sever calcium and phosphorus def. i see manganese also and potassium and ,magnesium .
But thats not all other elements are also but that will be corrected if you dry them out and lower your PH and give them a good drenching of a complete nutrients

Cal-mag def was my first thought