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, killing the leaf on it.
I feel a bit of a powdery feel after touching the leaves and so I suspect mold, yes? No?

I have been using neem and have read that I cannot use sulphur spray or sulphur burner for 4 weeks after spraying an oil product so I guess that's out. My humidity is pretty low in the 20's and 30's most of the time.
The shed measures 8x8x12 feet, but the actual grow is only about 4x5 feet. The air in the entire shed is replaced approx. every 4-7 minutes depending on whether the AC is running which increases flow.

what to do? Spray more oil if it's mold? I can't wait weeks to use sulphur. I also wonder if maybe more airflow would solve the problem?
Any and all thoughts appreciated.

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.

It looks like you could have a root problem. Carefully pull one out of the pot and feel around for roots. If growing right it should be a big wad of roots. Sometimes caused by overwatering. You need very good drainage for MJ roots. They need oxygen at the roots to grow good. You might try some root growth hormones, but I would check the overwatering issue first.

Thanks very much, here are some thoughts on your input:

Heat stress: Nope, it happens at the bottom first.

Nute burn: Nope, I have backed off a little on nutes and some leaves are even turning a little pale and tips are not burned like that.

Humidity: Usually my plants have loved the low 20's and 30's humidity in flower, don't think these would be any different.

Root problem: Well, maybe I suppose, I don't have much experience there. I transplanted them not too long ago and the roots looked fine and well developed, just gave them some more room.

Overwatering: Well, it certainly is pretty warm/hot in there and I know that adds to the potential lack of oxygen to the roots which can cause root rot. I have seen that before but it really didn't look exactly like this, then again, maybe it doesn't have to, but it is odd that the upper part of the plant is not affected (yet). I do use a bit of hydrogen peroxide when watering to try to get more oxygen down there but I think you could be at least partially right here, though normally I have seen the top of the plant drooping too when overwatering is the issue.

Anyone have other thoughts? Can we really completely write off all types of mold?

Thanks again....

Usually mold is just an issue if you have high humidity and poor air circulation.
You might try leaving a fan going 24/7 for awhile, but this isn't mold.

Well, if this really is a root issue, what to do?

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.

Thanks Killer,
I ended up lowering the temp in the room and that seems to have cured it. I believe you are right. Prolly basically a case of early root rot, but gone now as colder roots get more oxygen and I have continuted to add H2O2 when watering.