You can try a root stimulator like cannanutes rhizotonic.
You might want to carefully repot or atleast seperate the pot from the plant to see if its too damp. You could try putting a fan on the floor to blow the pots dry. It really does look like the roots are having trouble getting oxygen or you could possibly be smothering the plant with neem oil. You can't spray too much or it will do the same thing. If you got a bug problem, spray them once every 3 or 4 days.
killerweed420 Reviewed by killerweed420 on . Is this Mold? What to do? PICS..... Hi all, I'm in very early flower indoors under 1000w HPS, in soil and coco fiber w perilite. temps are 80's and 90's. I feed with 10-30-20 one part nutes. Something is affecting my plants, it starts on the grow tips of the lower branches and works its way up the plant. Affected new growth tips are droopy and turn black or grey and die while still very small, essentially ending most growth of the branch it heads. Also, some leaf stems suddenly wither and shrink to the width of a human hair, Rating: 5