Indoor LED 350Watt leaf burn or what?

[The Squid]

Funny, my Blackstar says 240 UV flowering model on it. LED lights definately cause light bleaching but I have yet to see one actually burn a leaf. That type of damage comes from the radiant heat of HPS or getting too close to high intensity fluorescent. Seeing as the damage to the OP's plant goes halfway down the plant I'd say it's safe to rule out light burn. I'm still going with P dep, I've seen the exact thing on my plants when I had ph issues.

Indeed. I wasn't even gonna go there and troubleshoot on the deficiency problem. Leaving that to the more knowledgeable guys, just felt like I needed to put that out there as far as LEDs as to not mis-represent or mislead anyone.

 

[agito]

it does look like ph swing ive had previous

 

[auto-p]

There are LEDs that include UV light for sure, you can experience burn from LEDs, don't be fooled. It's more likely that you will notice bleaching first though,since they don't put out too much heat, which means it's too close. But that looks like a ph issue as already stated. Just wanted to say this about LEDs and UV. Blackstars have UV spectrum included and those are the most popular here, that is actually on of many +'s about LEDs, is the UV that they include.

Ok- sorry, I should have been more precise in my response.

LEDs have NO ionizing UV. (UVB)

This is the type of UV that causes burning, protein damage and DNA damage.

LED UV sources are all near-visible non-ionizing UVA, and will not cause burning, protein, and DNA damage. UVA doesn't have enough energy in each photon to cleave proteins directly.

The only issues we've seen with LEDs is that they can be very powerful, and can cause bleaching due to localized heating of proteins.

(and to be more precise-- LED UVB sources do exist- but aren't used for grow lights.)

MH, CFL, FL, and HPS sources all have some small amount of UVB. (although most are very small amounts, with MH usually the highest UVB levels.)

 

[Mr Piggy]

Yes, but that's not what cooks the plants from the grow lights. That's the point here. UV has nothing to do with what's going on.

 

[auto-p]

Yes, but that's not what cooks the plants from the grow lights. That's the point here. UV has nothing to do with what's going on.

Yes, that was my point too. Sorry, being a little technical, but was wanting to point out one of the HUGE advantages to lighting with LEDs -- you never have to worry about UVB burning.

Right now my grow has about 1100 watts of LED, probably way overkill... And my grow room never goes over 80 degrees, and I never have to worry about burning the plants.

 

[Mr Piggy]

I have never in my life heard a grower be concerned about too much UVB from their grow lights. I have seen growers add UVB specific flouros to their grow area in attempts to up the potency and tricome production of their plants. If UVB was a concern then why would the tiny amounts put out by grow lights be more dangerous than the larger amounts put out by the sun itself? When Lights get baked in the radiant heat from getting too close to a HID bulb it's not the UVB burning them, it's the radiant heat. As far as flouros, they have to be touching them or within less than half an inch to burn. Once again this is from heat. I would really like to see some links to back up your argument as it is strange and doesn't seem right to me.

 

[auto-p]

I have never in my life heard a grower be concerned about too much UVB from their grow lights. I have seen growers add UVB specific flouros to their grow area in attempts to up the potency and tricome production of their plants. If UVB was a concern then why would the tiny amounts put out by grow lights be more dangerous than the larger amounts put out by the sun itself? When Lights get baked in the radiant heat from getting too close to a HID bulb it's not the UVB burning them, it's the radiant heat. As far as flouros, they have to be touching them or within less than half an inch to burn. Once again this is from heat. I would really like to see some links to back up your argument as it is strange and doesn't seem right to me.

I've seen burns from UVB-- both plants and corals from MH bulbs. Usually from high spectrum bulbs (20000K.). Close to the bulb, UVB levels are really really high, and can cause chromosome damage and cook offs.

You know, you might be able to help me out. --- I'm designing some LED lamps for growing right now, and I'm looking for some scientific data on grow spectrums... Unfortunately, I can't find any. Everything in this hobby seems to be anecdotal only, which as far as I'm concerned, is useless. (or less than useless--)

I have chlor A and chlor B and caratinoid data. But what everyone chats about doesn't seem to actually have anything to do with actual absorption spectrums. I'm looking for studies on THC and cannabinoid production specifically.

My last personal grow was under 1100 watts of LEDs, mainly 420nm Cree, and Cree broad spectrum whites.

In my current grow, I'm using the same 1100 watts, but more spread out, with more plants. Didn't seem to change a thing-- if anything my current grow is larger at five weeks than my previous grow. (but probably due to temps being about five degrees warmer in my grow room this time of year)

After this grow is complete, I'll be changing over to Osram horticultural 670nm LEDs. I want to see what happens when a grow occurs with only a single spectrum-- and if it changes anything.

Thanx!

 

[Hugo]

It really doesn't look like a P def to me. I may be really off here but it's not P.

First and this is way important (!), because P is highly mobile any symptom would appear in the lower oldest leafs first, leafs usually become a darker green and exhibit dull blues or patched marks. The stem of the leaf would clearly be reddish (on some strains is common to have red stems, but when you have P def you'll definitely have red petioles) and the leafs would curl downward, not upwards. I see none of this important symptoms here.

What I see is middle leafs highly affected and lower leafs starting to be, chlorosis in between veins working their way from out to inside, burned edges curled upwards. Iron (Fe) and Magnesium (Mg) look very similar and exhibit this traits except with Mg it starts first on the lower leafs. The picture doesn't help much to be more confidant on diagnosis. An iron def is usually a indication of a pH imbalance, so pH should be adjusted @ top priority!

The literature says that Fe def usually occurs with company of Zn and Mn defs.

 

[Mr Piggy]

All I can tell you is I think single spectrum growing is foolish and you will get diminished results from it. I have always grown mixed spectrum, mainly with red and blues no matter the lighting type. You can look up the specs on blackstars anywhere on the web if you want info on the nm ranges I use. Your personal experience with coral may be extensive, but it means nothing to me as I have no way to verify that. I was asking for a solid link to back up uvb damage from standard grow lights used by pot growers, not for a shift in conversation. Not trying to be rude, just want the uvb mystery cleared up.

You're right hugo, there does appear to be more going on than just P but like I said, I've had P damage like that before. I also see purple in some of the stems. There does appear to be a Mg problem as well, and some yellowing starting to come up from the bottom that might be N. A full plant picture would be much better but I think we're all in agreement here, PH is the culprit! That bastard PH that strikes in the night.

 

[Hugo]

Eheh, i don't think there's more going on than just P. I don't think P at all

pH control is our common goal! Such a smooth criminal, the bastard!!

So venars, what's up with your pH?