it's not PM, looks like ya toasted them how far away is the light..
heat stress maybe or nute burn.. try and higher ya RH a bit to..

mick.
mickrick Reviewed by mickrick 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