Quantum Boards burning plants.

Kushash said:

What have you fed them other than water in the last few weeks and in what amounts?

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When this issue first occurred, I just went through my normal routine. For example, I transplanted the Super Lemon Haze into the 3 gallon pot and let it veg two more weeks before flowering. So, I am confident it's not the nutrient issue. When I raised this SLH higher, at the same level as the bigger plant, it burned at around 30K LUX.

unfiltered said:

Here's a pic.

The lighter color one is the one that's burned severely but I have managed to stop or slow down the damage. I got 4 more weeks to go so hopefully there's enough healthy leaves for photosynthesis so she would finish.

As for the greener plant (Super Lemon Haze) at the bottom, you can see the bigger fan leaves got burned when I raised it higher. Now, it's sitting at a lower/safe distance from burning hell.

View attachment 4423020

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Shit, idk man. These are older plants. Have they always been under qbs?

A lot of folks run in 80s with LED.

Personally im really keen on light burn and usually question a growers distance. But your pics don't look like typical light burn.

Have you grown in this soil before?

Were you having issues in veg that carried over into flower?

I have had problems in veg previously when its been cold, the solution was to raise my temps and lower my hours of light, since that particular tent I couldn't raise the light or dim past 50%.

Anyway, this soil, is it new to you,? tried and tested by others?

R Burns said:

So then I would look to genetics. Specially how it processes/uses calcium. Also might just need more, but you seem to know what you're doing. They have weak cuticle, can't take the intensity. Have to work it like hardening off. I have this go on alot with moving to quantums from fluorescent. Some are a real pain in the ass about it.

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Yes, I believe that plants grown under QB's need extra Calcium and Mg. But you can't give them too much as that would lead to toxicity. I do give these plants plenty of Calcium now. For sure, QB's can induce symptoms that look like Cal/Mag def.

But anyway, like I said, this light burn is happening to two very different strains. The big one, Black Diamond, is an indica hybrid while the SLH is obviously a sativa dom.

unfiltered said:

I have two strains in the same tent. The light burned both plants as explained in the OP.

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Sorry, not the best reader...... First question I ask any led grower, are you heavily aerating the soil mix? Much more than under HID, slower transpiration rates. It's vital...

"Dialed in vpd" doesn't look like that,

that looks systemic and mobile. Lowers are effected...... Could be your Los mix, root zone, fungal, environmental, etc. Not a quick fix from an internet opinion.

Do what you think improves the outcome, it's about saving the crop..... So raise the lights if that helps you finish without major yield loss...

unfiltered said:

Could 4 QB's in the same tent affect the reading? When the HLG or other sources recommend the PPFD range, is that the general reading at the canopy and it doesn't matter how many QB's you have?

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Could be overlapping some at points. Maybe it's reflecting like hell with the tent closed? Whats the recommended footprint?

coreywebster said:

A lot of folks run in 80s with LED.

Personally im really keen on light burn and usually question a growers distance. But your pics don't look like typical light burn.

Have you grown in this soil before?

Were you having issues in veg that carried over into flower?

I have had problems in veg previously when its been cold, the solution was to raise my temps and lower my hours of light, since that particular tent I couldn't raise the light or dim past 50%.

Anyway, this soil, is it new to you,? tried and tested by others?

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You are very good with diagnosing. The big one is a very old plant that lived outside in the summer. For some reason, she reveged and was messy; and thus not ready for natural flowering outdoor. So, I brought her in under these QB's. She reveged and grew with super dark leaves proabably due to under water and the light being too close. She was droopy all the time. Then I managed to correct the issue and got her perky before flowering, thinking I fixed the issue. Then during flowering, I lower the light and increased the intensity and she drooped again.

Anyway, the soil is re-used and nutes probably not well balanced since it's been living in it for months. But the thing is the new SLH also burned. So that's why I have ruled out nutrient as the main issue. Sure, the big plant probably got cal/mag deficiency to start with but how do you explain the SLH being burned too.

I didnt see any comments to this effect..

Did you mention your pH? Can lock out nutrients if not in correct range

PSUAGRO. said:

Sorry, not the best reader...... First question I ask any led grower, are you heavily aerating the soil mix? Much more than under HID, slower transpiration rates. It's vital...

"Dialed in vpd" doesn't look like that,

that looks systemic and mobile. Lowers are effected...... Could be your Los mix, root zone, fungal, environmental, etc. Not a quick fix from an internet opinion.

Do what you think improves the outcome, it's about saving the crop..... So raise the lights if that helps you finish without major yield loss...

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For sure, the big plant got soil issue as she's been living in that 20 gal fabric pots since June this year, that's 5 months. But I have top dressed a couple of time. And yes, the lower leaves got the same interveinal chlorosis and necrosis spots. So, I think the big plant got both light burn and nutrient imbalance issue.

The SLH, greener plant, definitely do not have nutes issue as it was transplanted into well cooked LOS. And the burnt is the result of QB's.

MrToad69 said:

I didnt see any comments to this effect..

Did you mention your pH? Can lock out nutrients if not in correct range

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I usually don't take pH reading but did for the bigger plant due to the issue. It was on the acidic side for sure. Like I said above, I think the bigger plant got both light burn and nute imbalance (i.e. low pH, lockout, nute deficiency).

What I am interested in figuring out is the light burn.

It really doesnt look like light burn.
Maybe overwatering, bad soil mix, nutes, ph.
That said, i have never ph'd in soil so its probably one of the latter

Your pH might be affecting nutrient uptake, which can create a stressed and sensitive plant, possibly allowing it to burn.

I'm guessing your pH is off quite a bit, no offense, since most growers can tell you exactly the pH they are watering with...For soil target a pH around 6..coco around 5.8. If you're in the wrong pH range then some nutrients are getting locked out..

If you need to foliar spray. cal-Mg .target a pH closer to 7 as Calcium is absorbed at a higher level

Toad

Anyway, thanks guys for chiming in. I'm going to slowly increase the intensity by 1K LUX every few days and see how far I can push them. I'll report back.

For those running 4 x QB288 in a 4x4 tent, what's your QB reading/setup like? LUX, PPFD, watt, and distance to canopy?

Im seeing things I wouldn't tend to see and things im not seeing that would expect if it were due to light intensity.

Burn tips everywhere.
Eagle claw.

Not much yellowing, I would expect it to look like a magnesium/zinc def but in the wrong places, new leaves if it were quick light burn, old ones if it were slow light burn. I would expect to see the leaf vein to be red too.
To my eyes, could be wrong, looks like an abundance of one element locking out others and been quickly compounded by increased light levels.
Even the new plant has pretty bad burnt tips, which is not light burn.

Thing is though, I have never built a soil nor grown in soil, im a coco guy so never had that kind of issue outside of the odd occasion where I have had a lockout from salt build up.

Don't get me wrong, I have seen many plants burned quick under boards, including my own first time I set them up, but never at that distance or par.

MrToad69 said:

Your pH might be affecting nutrient uptake, which can create a stressed and sensitive plant, possibly allowing it to burn.

I'm guessing your pH is off quite a bit, no offense, since most growers can tell you exactly the pH they are watering with...For soil target a pH around 6..coco around 5.8. If you're in the wrong pH range then some nutrients are getting locked out..

If you need to foliar spray. cal-Mg .target a pH closer to 7 as Calcium is absorbed at a higher level

Toad

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For the big plant, for sure the pH was off and had lockout. But how do you explain the smaller SLH plant being burned in freshly cooked living organic soil? I have just put another plant in the flowering tent, using the same cooked LOS and it's praying and being very healthy.

coreywebster said:

Im seeing things I wouldn't tend to see and things im not seeing that would expect if it were due to light intensity.

Burn tips everywhere.
Eagle claw.

Not much yellowing, I would expect it to look like a magnesium/zinc def but in the wrong places, new leaves if it were quick light burn, old ones if it were slow light burn. I would expect to see the leaf vein to be red too.
To my eyes, could be wrong, looks like an abundance of one element locking out others and been quickly compounded by increased light levels.
Even the new plant has pretty bad burnt tips, which is not light burn.

Thing is though, I have never built a soil nor grown in soil, im a coco guy so never had that kind of issue outside of the odd occasion where I have had a lockout from salt build up.

Don't get me wrong, I have seen many plants burned quick under boards, including my own first time I set them up, but never at that distance or par.

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Good eyes you got there! The smaller plant got tip burnts due to too much nutes and it's a sativa dom which usually doesn't like a lot of nutes. The reason why this smaller plant got tips burnts was because it started yellowing at the top and all over, so I thought I had nute deficiency with my freshly cooked soil. So, I top dressed with all the goodies and she got nute burnt. But if you look at the fan leaves, there's serration necrosis and interveinal yellowing and that's from the light burn.

So, I think you are correct in that the lockout compounded the light burn issue. And me being reactive, afraid to lower the light and keep thinking that if I do, it would burn some more. The big plant did have yellowing before the necrosis and tip burnt, but I managed to stop the yellowing by giving it too much nutes.

Anyway, I will keep an eye out on the pH and will correct it. And then I will slowly increase the intensity now that the plants are older and can take on more light.

Unfiltered..
I think the light is distracting you from the real issue..nutrients..Strains have different requirements hence the different reactions in the se environment.

MrToad69 said:

Unfiltered..
I think the light is distracting you from the real issue..nutrients..Strains have different requirements hence the different reactions in the se environment.

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You are right in a way. I think I have both nutrient and light issue. The reason is that I have a stand-alone QB228 v2 with 660nm and have managed to burn 3 seedlings too. That's why I am bringing up the light issue in the first place.

Do you think they will recover from the burnt?

I it 65000 lux

swedsteven said:

I it 65000 lux

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distance to canopy? in flowering I suppose?