Light burn consistently with cobs/strips after 5th week of flower at only 30k lux?

search for mineral wheel


and dont give so much on the lux of your meter, it could be more in real.
while it really doesnt look like the typical light stress (which could have many faces??).

cobshopgrow said:

search for mineral wheel

maybe lots of iron in the tap?

and dont give so much on the lux of your meter, it could be more in real.
while it really doesnt look like the typical light stress.

Click to expand...

Thanks, that's exactly what I was looking for.

Hmmm.. so an excess of sulfur could interfere with Cu. I do get extra sulfur in the Mag Pro supplement. Really not sure if it's nutrient related though, but can't rule it out.

not sure if sulfur problematic for Cu, just forces its uptake or?
no lockout.
sulfur isnt that problematic, i have lots in my tap, about EC 0.3 are given.
dont grow with it, but it dont kill normal plants nor ours.

Mulders chart shows a few things that lower copper uptake.

Manganese
Phosphorus
Iron
Nitrogen.

Magnesium can increase the uptake of the last 3 of those.

Only other thing I have heard about dynagro is a lot of people reporting it precipitating in the bottle.

This is a weird situation , you could check your water content out online, see if there is high iron content.
Or maybe its worth trying a different nutrient line for one crop ?

Flying blind here really.

But lets say if I was right about the tops been in a dead zone with no air flow and microclimates around the leaves, that could explain why your getting leaf temp readings higher than your expecting and possible suggest a cause of heat stress which in turn could cause them to lap up more N since plants will do that causing a whole bunch of other issues.

Lots of ifs buts and possibilities

id drop the mag supplement, did you see a Mg def before adding it? See this a lot....theres probs enough in the tap water and base nutes.

thats me done!

good luck

All i can say it doesnt look like light burn. I remember seeing something similar on hybrids plants when he wasnt getting his nutes right. Im inclined to say too much calmag aswell with lockout of ssomething...

coreywebster said:

But lets say if I was right about the tops been in a dead zone with no air flow and microclimates around the leaves, that could explain why your getting leaf temp readings higher than your expecting and possible suggest a cause of heat stress which in turn could cause them to lap up more N since plants will do that causing a whole bunch of other issues.

Click to expand...

I think this is probably the most likely explanation. Only the leaves up top are affected, all of the lower growth is fine, and it only happens when the plant has gotten tall and the top is far from the intake of the tent.

Do you happen to have a source about heat stress and Nitrogen uptake? I'd definitely be interested to read that.

I've seen a lot of folks use dyna gro with success, and nowadays most nutrient lines don't leave much room for error if you use the whole line and get your pH right.

I live in a small town and was able to find a water report for this year and iron is less than .01ppm.

So I'm thinking you must have the most likely explanation... I won't know until my next crop is 6 weeks into flower.... But this seems to be the most likely explanation.

Thanks for thinking through all this!

Animatey said:

I think this is probably the most likely explanation. Only the leaves up top are affected, all of the lower growth is fine, and it only happens when the plant has gotten tall and the top is far from the intake of the tent.

Do you happen to have a source about heat stress and Nitrogen uptake? I'd definitely be interested to read that.

I've seen a lot of folks use dyna gro with success, and nowadays most nutrient lines don't leave much room for error if you use the whole line and get your pH right.

I live in a small town and was able to find a water report for this year and iron is less than .01ppm.

So I'm thinking you must have the most likely explanation... I won't know until my next crop is 6 weeks into flower.... But this seems to be the most likely explanation.

Thanks for thinking through all this!

Click to expand...

No problem man, just bouncing ideas around trying to be logical, Hopefully it helps.
You will have to let us know next crop.

coreywebster said:

No problem man, just bouncing ideas around trying to be logical, Hopefully it helps.
You will have to let us know next crop.

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Thanks again man!

I snuck in this edit but you're too fast lol...

Do you happen to have a source about heat stress and Nitrogen uptake? I'd definitely be interested to read that.

Animatey said:

Thanks again man!

I snuck in this edit but you're too fast lol...

Do you happen to have a source about heat stress and Nitrogen uptake? I'd definitely be interested to read that.

Click to expand...

There's a brief mention of it here

But the gist of it is when they are heat stressed they will drink more and with N been so available they will always take it up so the result is more N uptake even though the plant doesn't really need it.

one more thing,

lotta Mg supplements also contain N, does yours OP?

lukio said:

one more thing,

lotta Mg supplements also contain N, does yours OP?

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It does, but not much and I don't use much of it. I only use like 3ml per gal at most and usually 2 or less.

The Mg supplement is mainly Mg, Su and P.

yeah figured.

do you know their base Mg ppm?

lukio said:

yeah figured.

do you know their base Mg ppm?

Click to expand...

Not sure about the PPM but the base bloom nutrient has this analysis:

Mg in the water
Mg in the base
Mg supplement...

MagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMagMag