Leaf necrosis happening every mid flowering

[Boogyman69]

Hi
Been growing for years but for the last 4-5 grows I've been getting some sort of leaf necrosis during mid flower.
Happens at around week 4. Everything is pretty much spot on.
Coco, LED
pH 5.8 in with 6.0 runoff
EC 1.2 in, EC 1.1-1.5 runoff
50g smart pots

The problem only happens below the canopy, the top of the canopy is actually quite perfect with nothing wrong (pic posted).
Could it be the plant is sacrificing lower growth?
I'm totally stumped and looked at every leaf symptom photo online and either they're wrong or they don't look exactly the same.
Any help/suggestions to fix this would be appreciated

 

[bluter]

can't really tell without seeing the whole plant with problem leaves attached.
that said it looks a bit like phos def. they don't look to be yellowing which would be a general pull from the leaf.

i'm not so sure it's really a problem judging by the pic of the tops. it could be strain related, or maybe you've changed something slightly and didn't think to account for it. i wouldn't worry unless you've had trouble getting them to the finish.

 

[Bill284]

Hi
Been growing for years but for the last 4-5 grows I've been getting some sort of leaf necrosis during mid flower.
Happens at around week 4. Everything is pretty much spot on.
Coco, LED
pH 5.8 in with 6.0 runoff
EC 1.2 in, EC 1.1-1.5 runoff
50g smart pots

The problem only happens below the canopy, the top of the canopy is actually quite perfect with nothing wrong (pic posted).
Could it be the plant is sacrificing lower growth?
I'm totally stumped and looked at every leaf symptom photo online and either they're wrong or they don't look exactly the same.
Any help/suggestions to fix this would be appreciated

Hey @Boogyman69 great looking girls. As your damaged leaves are below your canopy i wouldn't be terrible concerned. If it progresses to uppers id be worried. Were the bad leaves touching soil or the pot?
Bill

 

[Weaselcracker]

It’s most typically associated with phosphorus deficiencies. There are a lot of possible causes.


You would have to kind of dissect your entire nutrient routine, your pH, environmental conditions, etc. There are a lot of grow conditions that can lead to deficiencies.

But since your plants look so great already, I wouldn’t worry about it very much. Just keep it in mind and keep an eye on things. You may be able to stumble upon the cause and make a small change or two that will improve it and get rid the deficiencies. But I wouldn’t go messing with the formula very much.

 

[Boogyman69]

Thanks for the replies,
however I'm still quite concerned because the heaviest nuggets I've grown have all had perfect leaves top to bottom.
My previous grows, the nugs actually looked big but the dry weight was dissapointing which is why I think this has something to do with the problem.
I have read somewhere that the plants tend to kill off parts of itself where there is little light/wind but I really doubt it. Could it be my coco is so filled with roots that I'm getting waterlogged? (straight canna coco with nothing else)
Here's my canopy thickness (probably about 50cm !), how dark the bottom is (manually taken so it looks like real life) if it could help identify this problem.
I also took a photo where you can see a lot of the necrosis happening (plucked most of it off on some plants but left one plant with it on).
In the end I'm hoping someone had the exact same problem and solved it for their grow.
Thanks again for the help.

EDIT: I have actually changed my A and B brand, but surely it can't be as simple as that.

 

[bluter]

it's dark down there.
a plant will sacrifice lowers that get no light. you don't have penetration to those points.

 

[Bill284]

Thanks for the replies,
however I'm still quite concerned because the heaviest nuggets I've grown have all had perfect leaves top to bottom.
My previous grows, the nugs actually looked big but the dry weight was dissapointing which is why I think this has something to do with the problem.
I have read somewhere that the plants tend to kill off parts of itself where there is little light/wind but I really doubt it. Could it be my coco is so filled with roots that I'm getting waterlogged? (straight canna coco with nothing else)
Here's my canopy thickness (probably about 50cm !), how dark the bottom is (manually taken so it looks like real life) if it could help identify this problem.
I also took a photo where you can see a lot of the necrosis happening (plucked most of it off on some plants but left one plant with it on).
In the end I'm hoping someone had the exact same problem and solved it for their grow.
Thanks again for the help.

EDIT: I have actually changed my A and B brand, but surely it can't be as simple as that.

Those leaves definitely aren't touching soil or your pot. But get no light.
Your ph and ec seem fine. How is your temp rh and air circulation?

 

[Weaselcracker]

Well I don’t think your coco is getting waterlogged. Leaves naturally die off when they are shaded. When it happens to me they don’t normally turn black but it still could be the same process. Honestly I don’t think you have anything much to worry about there.

 

[Boogyman69]

Those leaves definitely aren't touching soil or your pot. But get no light.
Your ph and ec seem fine. How is your temp rh and air circulation?

I have the Can Fan QMAX EC 355mm and am running multiple ceiling fans so pretty much perfect air ciculation (above canopy). RH has always been high 70-80 but in the past I never experienced this problem.

I'm just wondering because my smart pots are so wide (used to use airpots) that I'm getting some salt buildup in areas on top my drippers aren't spreading to. I just realized i only started using smartpots. They're a lot wider than the pots I used to use, i think these are actually almost 15 gallons and I may have salt buildup pockets?

 

[Weaselcracker]

EDIT: I have actually changed my A and B brand, but surely it can't be as simple as that.

Why not? Unless you can analyze the contents of your bottles and break it down to the individual elements there is no way to really know what the plants are getting. Switching nutrients will usually change the outcome.

PS. The guaranteed analysis list on the backs of bottles are not to be trusted. They are just a legal minimum, and even with that, companies routinely lie about the contents

 

[Emilya Green]

It does look like phosphorus pickup is lacking... have you tried using myco when building those large containers?

 

[Bill284]

I have the Can Fan QMAX EC 355mm and am running multiple ceiling fans so pretty much perfect air ciculation (above canopy). RH has always been high 70-80 but in the past I never experienced this problem.

I'm just wondering because my smart pots are so wide (used to use airpots) that I'm getting some salt buildup in areas on top my drippers aren't spreading to. I just realized i only started using smartpots. They're a lot wider than the pots I used to use, i think these are actually almost 15 gallons and I may have salt buildup pockets?

80 % humidity isn't helping you any. Make sure your air is circulating well below canopy.
Bags shouldn't be an issue compared to air pots. But I'd use air pots any day first. You might want to think about investing in a dehumidifier for future grows.

 

[CrimsonEcho]

I have the Can Fan QMAX EC 355mm and am running multiple ceiling fans so pretty much perfect air ciculation (above canopy). RH has always been high 70-80 but in the past I never experienced this problem.

I'm just wondering because my smart pots are so wide (used to use airpots) that I'm getting some salt buildup in areas on top my drippers aren't spreading to. I just realized i only started using smartpots. They're a lot wider than the pots I used to use, i think these are actually almost 15 gallons and I may have salt buildup pockets?

i’d have to agree with the other guys on your plants looking fine and happy so you shouldn’t worry that much about a couple of leaves. chances are you will screw them up worse if you try to correct this minor glitch at this point but i’ll just say this 70-80% rh is very problematic, i had crazy bud rot before and the tighter and denser the nugs get your chances of getting it increases. i’d shoot for at least under 60. other than that seems great.

 

[Boogyman69]

Yea, I actually have a 4-5hp dehumidifier but it can't keep up. The intake air moves out so fast that the dried air gets vented anyway. I don't get budrot with this strain as its mould resistant. There is probably too many plants hence the humidity.

Looking at the PH charts for phosphorous it starts at 6. Should i maybe raise my pH? I dont think my pH pen is a problem also because i've actually taped 3 different pH pens side by side.

I've looked at tens and tens of phosphorous leaf deficiency photos online and only 2-3 were similar. On my leaves, most of the darkness starts on the serrations so I couldn't actually be sure if it was phosphorous.

EDIT : I know a lot of people seem fussed about the high humidity, and I've been growing for years in 80-90% without any problems (circulation is a must though) There is a thread called "lies our fathers told us" online detailing this as well as a medigrow youtuber who had one of this fans or something fail and ended up with dripping wet walls but such a good result he only grows in high humidity! I'll see if i can find the channel.

I remember about 10 years ago though, when my room wasn't so filled i actually used to get budrot when it was dry. (wasn't using ceiling fans at that stage though).

"Botrytis is favored by cool temperatures (50° to 60°F) and high relative humidity, and may sporulate on dead or dying plant tissue. It can also be severe at higher temperatures."

Just throwing out my experience on this growing adventure that hopefully someone can learn a thing or two.

 

[Bill284]

Yea, I actually have a 4-5hp dehumidifier but it can't keep up. The intake air moves out so fast that the dried air gets vented anyway. I don't get budrot with this strain as its mould resistant. There is probably too many plants hence the humidity.

Looking at the PH charts for phosphorous it starts at 6. Should i maybe raise my pH? I dont think my pH pen is a problem also because i've actually taped 3 different pH pens side by side.

I've looked at tens and tens of phosphorous leaf deficiency photos online and only 2-3 were similar. On my leaves, most of the darkness starts on the serrations so I couldn't actually be sure if it was phosphorous.

Coco is hydroponic and requires a ph of 5.8

 

[Weaselcracker]

It’s just never that simple. Well, the occasional deficiency can be simple but it hardly ever is.

If you’re determined to do something about it. I would look at dialling in the environmental conditions first. Look at your venting situation and dehumidifier setup, look at VPD charts and see if you can get your humidity and temperatures closer to optimum. After that start looking at your nutrient routine and try to figure out what you’re actually feeding the plants and if anything is out of line.

I think you’re trying to fix something that’s not broken though. Want to trade grows?

 

[bluter]

80 % humidity isn't helping you any. Make sure your air is circulating well below canopy.

you can do it if your vpd is there and you don't get big temp swings in day/night or other conditions that help harbor mold spores and other stuff.

You might want to think about investing in a dehumidifier for future grows.

maybe not a bad idea regardless.

Yea, I actually have a 4-5hp dehumidifier but it can't keep up. The intake air moves out so fast that the dried air gets vented anyway. I don't get budrot with this strain as its mould resistant. There is probably too many plants hence the humidity.

extraction is the cheapest method to move wet air. the more plants, the more transpiration, the more moisture in the air.

we did larger grows where the humidity climbed to constant 70% and over in the flower rooms, when the ambient outdoor rh% was 15. never had any issues at all, and some of the best weed. it was like working in a sauna though.

edit: we moved mountains of air though. individual rooms with active intake and exhaust, as well as circulation, all dumped in to a lung room with it's own scrubbing and exhaust to outdoor.

sealed area under constant negative pressure.

Looking at the PH charts for phosphorous it starts at 6. Should i maybe raise my pH? I dont think my pH pen is a problem also because i've actually taped 3 different pH pens side by side.

stick to hydro ph - 5.8. the drift will take you right through 6 fast no matter.

I've looked at tens and tens of phosphorous leaf deficiency photos online and only 2-3 were similar. On my leaves, most of the darkness starts on the serrations so I couldn't actually be sure if it was phosphorous.

edging can be an early ask. a lot of times it's read as a tox.

EDIT : I know a lot of people seem fussed about the high humidity, and I've been growing for years in 80-90% without any problems (circulation is a must though) There is a thread called "lies our fathers told us" online detailing this as well as a medigrow youtuber who had one of this fans or something fail and ended up with dripping wet walls but such a good result he only grows in high humidity! I'll see if i can find the channel.

you can always stretch one parameter if others have a balance. we got away with high rh in flower due to other things being in balance. we only got those results on winter grows, in summer grows there were all sorts of issues.

Want to trade grows?

been thinking this myself. my run is looking a shocker right now ...

 

[CrimsonEcho]

EDIT : I know a lot of people seem fussed about the high humidity, and I've been growing for years in 80-90% without any problems (circulation is a must though) There is a thread called "lies our fathers told us" online detailing this as well as a medigrow youtuber who had one of this fans or something fail and ended up with dripping wet walls but such a good result he only grows in high humidity! I'll see if i can find the channel.

I remember about 10 years ago though, when my room wasn't so filled i actually used to get budrot when it was dry. (wasn't using ceiling fans at that stage though).

"Botrytis is favored by cool temperatures (50° to 60°F) and high relative humidity, and may sporulate on dead or dying plant tissue. It can also be severe at higher temperatures."

Just throwing out my experience on this growing adventure that hopefully someone can learn a thing or two.

dude i don’t know what lies your fathers told you but mine is a personal experience also. high relative humidity is a problem in most cases and many plants are not very resillient against mold, especially the ones that grow very tight nugs and indica doms. its ok if you are comfortable with high rh but i wouldnt go as far as calling it a lie. thats a bold claim and may cause many new growers much headache.

 

[bluter]

may cause many new growers much headache.

yes.

 

[Boogyman69]

I know you guys don't think anything is broken, but every grow where I've had great results have had perfect leaves bottom to top (I don't flush). My best was about 650gr/m2. For the last 3 or so since I've been seeing this problem and I've dropped to about 520-550gr/m2 which is a huge difference. I'm only worried as this has only started happening recently.

According to this VPD chart I'm actualy still in the green at 0.5kpa . But there are so many baseless VPD charts.

https://www.perfectgrower.com/knowledge/wp-content/uploads/2018/08/VPD_chart.png

Ok since now I've just added another fan on the floor, I also saw condensation on my fabric pot and touched it and licked it, it was slightly salty. I'm wondering if i'm getting salty sections in the coco where the water doesn't spread now.
Since I'll be chopping in 2 weeks I'll probably ride it out and change back to H&G like i used to as well as smaller pots.