heat or light burn?

I have a 400w and a 600w in a 4x4 tent.

My temperature probe directly in the light, in the middle of the two bulbs 18" below reads 81-84F constantly.

But if I put the probe under a leaf (shaded) it stays at 76-79F

Some of my pistils are getting burned. Would you think its temp or light burn?

The leaves seem ok, just the pistils. Mostly just the "tips" of the white pistil hairs.

And no its not just maturing.

Pistils have nothing to do with potency. If they are dieing or singed so be it. Just as long as the leaves aren't curling up at the edges at the top of the plant , you should be fine on temps. I'm sure its not light burn. You said it def. not just maturing but it may just be that. Also when pistils are pollinated they turn brown and start to retract. Make sure there are no male part just in case.

bostoner said:

Pistils have nothing to do with potency. If they are dieing or singed so be it. Just as long as the leaves aren't curling up at the edges at the top of the plant , you should be fine on temps. I'm sure its not light burn. You said it def. not just maturing but it may just be that. Also when pistils are pollinated they turn brown and start to retract. Make sure there are no male part just in case.

Click to expand...

I've been through a hermie, this isn't pollination. Or maturation. They aren't brown they're burnt.

But you did say you're sure it's not light burn...kinda agree, or I'd have leaves all burnt to F too.

I dont foliar feed either.

but if it's hot enough to singe the pistils, why is my probe reading so low? I see people grow in 90 sometimes...I'm no were close to that...

jakesnake said:

I've been through a hermie, this isn't pollination. Or maturation. They aren't brown they're burnt.

But you did say you're sure it's not light burn...kinda agree, or I'd have leaves all burnt to F too.

I dont foliar feed either.

Click to expand...

how close are the lights to the tips?

a picture says a thousand words. we're just shooting at fish in a barrel without a pic.

is it just the buds near the light or are lower/random buds doing it also? there are a few reasons for pistils to turn brown. a picture would be a big help. seriously.

jake, I know exactly what you are talking about, I have the same thing happening right now, Im running coco nutes 10ml/g in coir with pk 5ml/g, zyme 5ml/g and boost 5ml/g.
Im wondering if it needs less coco base nute, as it might be an early indicator of nute burn but i really have no idea im just guessing and plan on doing a total flush tomorrow and re adjusting a few plants to a lower dose and a few to a higher dose and the rest keep the same.
I also wonder if your medium has dried out completely resulting in the salt leeching, the plant i seem to see the most effects on is a bubba kush that soaks up water too fast.

Ill be posting pics tomorrow in hopes someone has a solid answer on this.

What type of light and setup are you using (hydro or soil) how far away are your lights from the top of your plants? What kind of nutes are you using? 78F is the temp you should be shootin for.

hey scuba, I do not believe it to be light burn because the burning is starting in random places, mostly lower buds and a few side shoots, seems to affect one branch at a time. My lights are roughly a foot and 10 inches away. coco, drain to waste with 20% perlite