Weird burn but run off and ph is fine. Week 6 Autoflower

Hey so I started getting this weird burn going over the last 2 weeks.

> Initially I thought it was light burn which after turning down the lights to less than half power has been ruled out.

> Then thought it was a PH issue so I tested run off PH and nope its perfectly locked in at 6.0 just like input.

What could this be? it suddenly popped up 2ish weeks ago right around the time pistils started showing up. Ive been giving it like 200ppms of calmag so its definitely not a calmag deficiency either.

Please help as this popped up just as this auto was going into flower. It was growing beautifully up to this point too.

My Setup -

Coco Perlite 70/30
Canna COCO a+b
Feeding @300ppm +200ppm calmag.
Feeding every 4 hours drain to waste in high frequency fertigation system.

Initially the issue looked like light burn and only affected the top most leaves. But as time went on some lower leaves showed weird yellowing too as seen in these pics. They also "came off" the plant really easily with almost no pressure.

Unaffected middle leaves that im sure will show symptoms soon if this keeps up

That looks like typical nute burn to me. Browning tips and margins and hitting up those top leaves cause it's warmer and drawing more water and nutes into them.

Did you up your nutes 3 weeks or so ago?

What's your RH like? Mine is always really low during the winter and much easier to burn plants with a low VPD. 31% now according to my remote screen. Only 20% here in my mancave.

Used to run my DWC at 500 - 600ppm max in winter to prevent toxic salts build up that would start frying the plants mid-flower and be crisping tiny bud leaves by chopping time.

Just my experiences. YMMV

Good luck!

OldMedUser said:

That looks like typical nute burn to me. Browning tips and margins and hitting up those top leaves cause it's warmer and drawing more water and nutes into them.

Did you up your nutes 3 weeks or so ago?

What's your RH like? Mine is always really low during the winter and much easier to burn plants with a low VPD. 31% now according to my remote screen. Only 20% here in my mancave.

Used to run my DWC at 500 - 600ppm max in winter to prevent toxic salts build up that would start frying the plants mid-flower and be crisping tiny bud leaves by chopping time.

Just my experiences. YMMV

Good luck!

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My RH is always around ~45-55. And temps were in the high 20s and early 30s celsius because of Australian summers but temps are starting to slowly go down as the summer is winding down.

Nutrient-wise haven't really messed with it too much other than gradually increasing calmag to 200ppms after the burn symptoms started showing up. I might give it a full flush on Tuesday just to see if that makes a difference. Other than that no idea what's going on here.

SupremeBudDrongo said:

My RH is always around ~45-55. And temps were in the high 20s and early 30s celsius because of Australian summers but temps are starting to slowly go down as the summer is winding down.

Nutrient-wise haven't really messed with it too much other than gradually increasing calmag to 200ppms after the burn symptoms started showing up. I might give it a full flush on Tuesday just to see if that makes a difference. Other than that no idea what's going on here.

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Don't your Canna nutes have Ca and Mg? If you were seeing burn symptoms adding more calmag is just going to make it worse. When I was doing DWC for years I never even had calmag for my first 30 grows and never saw symptoms of low Ca tho did see a bit of low Mg and fixed that with some Epsom Salts. I ran AN 3-part and it must have had enough Ca because I used RO or distilled water all the time so it didn't come from the water. Even now I use maybe 1/4 of what it says on the bottle.

CalMag is not a cure-all. VeloKelp by REMO might just be tho! Love that stuff.

I'm in northern Alberta and it's dry as a popcorn fart up here in the winter. Been pretty mild for the most part this year but getting a bit of snow now. 3 week of -30C and lower in Dec was early but Jan and now most of Feb has been barely freezing and often above to 4 or 5. Climate change is real!

stop the calmag not needed, PH 6.0 -6.4 - feed every water , feed approx 600-700ppm/1.2 i-1.5sh EC.... dont need to check run off dude thats bro rubbish

Scuzzman said:

stop the calmag not needed, PH 6.0 -6.4 - feed every water , feed approx 600-700ppm/1.2 i-1.5sh EC.... dont need to check run off dude thats bro rubbish

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This is coco coir though if I stop calmag those deficiencies are almost a guarantee???

SupremeBudDrongo said:

This is coco coir though if I stop calmag those deficiencies are almost a guarantee???

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I would stop the calmag until you see a deficiency and then maybe use epsom salts instead. With those dark green leaves there's lots in the plant already and as it's CannaCoco you're using it should have extra of both to work with coco like it's designed to do.

OldMedUser said:

Don't your Canna nutes have Ca and Mg? If you were seeing burn symptoms adding more calmag is just going to make it worse. When I was doing DWC for years I never even had calmag for my first 30 grows and never saw symptoms of low Ca tho did see a bit of low Mg and fixed that with some Epsom Salts. I ran AN 3-part and it must have had enough Ca because I used RO or distilled water all the time so it didn't come from the water. Even now I use maybe 1/4 of what it says on the bottle.

CalMag is not a cure-all. VeloKelp by REMO might just be tho! Love that stuff.

I'm in northern Alberta and it's dry as a popcorn fart up here in the winter. Been pretty mild for the most part this year but getting a bit of snow now. 3 week of -30C and lower in Dec was early but Jan and now most of Feb has been barely freezing and often above to 4 or 5. Climate change is real!

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From what I understood after listening to my local hydro store guy calmag is needed especially since Sydney Australia has reasonably low ppm water But ill give it a full flush on Tuesday just to see if that will help and start from a clean slate.

Also Jesus Christ man -30c is like a different world to +30C in Aus rn lol

no- thats bro rubbish in Aussie tap water has cal-mag already- you are under feeding the plants , I grow autos in 100% coco coir dont have issues - keep it simple, alot of others are the same

SupremeBudDrongo said:

Also Jesus Christ man -30c is like a different world to +30C in Aus rn lol

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We hit +42 summer before last when we had 2 'heat domes' late June and mid July. Coldest here at my house was -38.1 but when I worked further north was running my water truck at -51. None of the seismic drills could spin their bits so we went back to camp early that day and I sprayed my load on a freshly made snow bridge over part of a pipeline on the way back. Got the next day off with 12 hours pay too.

OldMedUser said:

We hit +42 summer before last when we had 2 'heat domes' late June and mid July. Coldest here at my house was -38.1 but when I worked further north was running my water truck at -51. None of the seismic drills could spin their bits so we went back to camp early that day and I sprayed my load on a freshly made snow bridge over part of a pipeline on the way back. Got the next day off with 12 hours pay too.

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I just read the back of my Canna Coco a+b bottles and it says it has more calcium than nitrogen by percentage. Think you were on to something in an earlier reply. Im gonna immediately cut down on the calcium and just feed some epsomsalt for mag. Gonna flush the plant regardless for a fresh start. Man I hope it pulls through this plant was motoring along beautifully then BAM odd burns and twisted new growth..

Yeah folks over use calmag which causes lockout of other nutes. Alot of plants dont need it no matter what medium its in. So I only use it if plant shows signs it needs it which is usually week 3-6 in bloom if at all. Not a fan of flushing cus it stresses plant and u need a recovery time. I'd just water a few days without nutes then start low feeds.

Grow Monster said:

Yeah folks over use calmag which causes lockout of other nutes. Alot of plants dont need it no matter what medium its in. So I only use it if plant shows signs it needs it which is usually week 3-6 in bloom if at all. Not a fan of flushing cus it stresses plant and u need a recovery time. I'd just water a few days without nutes then start low feeds.

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Most people make the mistake of flushing then waiting for the soil to dry out before feeding again. That can be critical especially with autos that run on their own timetable.

A decent flush is to saturate the pot with pH'ed water or better yet RO, allow to sit for an hour then pour thru the same volume of water ass the pot holds. Discard that water then follow with another volume that has 1/3 to 1/2 strength nutes and is pH'ed properly. Tap water with a high ppm leaves behind mineral salts with each watering that build up in the pots over time and can screw up the pH to the high side so just pH'ing your feed water does not change the pH in the pots. Starting with pure water makes sure that your tap water isn't the cause of any issues you might have as the grow progresses.

If you have hard water with high alkalinity I can guarantee that problems will arise because of that even in organic grows where pH isn't such a big deal.

OldMedUser said:

Most people make the mistake of flushing then waiting for the soil to dry out before feeding again. That can be critical especially with autos that run on their own timetable.

A decent flush is to saturate the pot with pH'ed water or better yet RO, allow to sit for an hour then pour thru the same volume of water ass the pot holds. Discard that water then follow with another volume that has 1/3 to 1/2 strength nutes and is pH'ed properly. Tap water with a high ppm leaves behind mineral salts with each watering that build up in the pots over time and can screw up the pH to the high side so just pH'ing your feed water does not change the pH in the pots. Starting with pure water makes sure that your tap water isn't the cause of any issues you might have as the grow progresses.

If you have hard water with high alkalinity I can guarantee that problems will arise because of that even in organic grows where pH isn't such a big deal.

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Quick question few days on. What does lower most roots peaking out browning mean? pls dont tell me its root rot..

SupremeBudDrongo said:

Quick question few days on. What does lower most roots peaking out browning mean? pls dont tell me its root rot..

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Peeking out of the drain holes then going brown? Just root pruning is all that is if that's what you mean. Fabric pots do that all over when root tips burrow into the damp fabric and get too much air they die too at the tips. When the tip dies or is cut off little side roots branch out from the main part of the root and spread fine feeder roots off in all directions which is a good thing.

I grow in plastic pots and cut the bottom of the rootball off when I up-pot just so that will happen.

Thanks a million so far cutting off calcium seems to have stopped the rapid yellowing/damage. But the plant is still not healthy. When I lifted up the pot there were brown roots at the bottom of the pot which got me thinking if this is early root rot that im seeing. Yield will be in the gutter it looks like..

SupremeBudDrongo said:

Thanks a million so far cutting off calcium seems to have stopped the rapid yellowing/damage. But the plant is still not healthy. When I lifted up the pot there were brown roots at the bottom of the pot which got me thinking if this is early root rot that im seeing. Yield will be in the gutter it looks like..

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If you're talking about lifting the rootball out of the pot and all the roots at the bottom of the ball are dead looking and maybe stinky? then that's a different story.

That could very well be root rot which is usually caused by overwatering, (which is different than soaking the pot good when you water), by watering too often because it's dry two knuckles deep at the top. As you are in that coco/perlite mix it should be wet all the time as opposed to peat that works best with a wet/dry cycle but not bone dry so the plants droop.

If it has a dead stuff smell to it then I'd use a bread knife and cut the bottom third of teh root ball of and put it in a clean pot the same if you have it with fresh medium on the bottom to keep it at the right height. Water it good so the new stuff ready for new roots. Good time to use a myco product like DynoMyco sprinkled liberally all over the top of the new medium in the out and sprayed to moisten it. I spray the bottom of the rootball too and will even sprinkle some myco on that.

Don't have to use stuff like that but it inoculates the roots so bad bacteria can't take hold and cause more rot.

SupremeBudDrongo said:

This is coco coir though if I stop calmag those deficiencies are almost a guarantee???

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Not really.

Are you using RO water?

40% of your nutrient are calmag.. sounds off.

What's 300ppm in EC?

I dont use calmag in my coco .