Yellowing on leaves

[Moose8810]

Problem:
Slight yellowing bands on some of the leaves, 3rd node from the top. Appears to be isolated to 3 of the colas.

Medium/grow method:
Coco/Perlite 70/30

Feed: and supplements used:
Calmag+ 3.5mL/gal
GH Flora trio @ 2mL Micro, 1 mL Gro, 2 mL Bloom per gal
Buddha's Tree Flower Burst 0.5mL/gal
Liquid Karma 2mL/gal
Hesi Supervit 1 drop/gal

All mixed to around 1.2-1.3EC, 5.8-6.1pH

Optic Foliar and Recharge every 5-6 days

water source:
Well water, 7.1pH and ~140ppm from the tap

Strain/age:
White Crack by Mephisto, day 43 from sprout

light used:
6x 3500K and 2x 2700K Autocobs

Climate:
5x5 Tent. 75-80F ambient, 68-74F leaf surface temps, 55-65% RH

Additional info:
We had a roughly 48 hour power outage about 4 days ago, when the leaves pictured were the top growth tips. Not sure if the two are related, the plants didn't seem too phased by the prolonged darkness other than the tops being a little yellow - these spots just never got green. I always make sure to water with plenty of runoff. I upped the EC tonight, thinking she may just be hungry.

Feed input tonight was 1.4EC, 5.8pH. Runoff was 1.2EC 5.8pH.

Any and all input is greatly appreciated! Hopefully I didn't leave anything pertinent out.

 

[Moose8810]

Here's a few shots right before lights on today if it helps at all. Anyone have any insight?

 

[MedGrower]

Seems like a slight magnesium deficiency on those leaves but since it is localized to these 3 colas, I wouldn't be concerned. We see this happening with COB's from time to time and as long as it doesn't get pronounced more, I don't think it needs any action. I think it is a kind of "light stress" in this case. You are already supplementing with CM and this is always a bit of a balance game. I think you're golden.

I think at this stage the need for Ca is reduced so you might as well simply supplement with Mg. Generally there are increased need for Ca at the vegetative stage, while in generative stage Mg plays a bigger role. Also Mg will absorb better at pH over 6.0. However, this is a minor issue and may not need any action regardless. Best.

 

[Moose8810]

Seems like a slight magnesium deficiency on those leaves but since it is localized to these 3 colas, I wouldn't be concerned. We see this happening with COB's from time to time and as long as it doesn't get pronounced more, I don't think it needs any action. I think it is a kind of "light stress" in this case. You are already supplementing with CM and this is always a bit of a balance game. I think you're golden.

I think at this stage the need for Ca is reduced so you might as well simply supplement with Mg. Generally there are increased need for Ca at the vegetative stage, while in generative stage Mg plays a bigger role. Also Mg will absorb better at pH over 6.0. However, this is a minor issue and may not need any action regardless. Best.

Thank you for taking a look! Any suggestions on a suitable Mg-only supplement? I've only ever run Calmag all the way through, would lowering the dose a bit work? This is my second coco grow, first one had a lot of issues at about 1-2 weeks further on and upping the Calmag to 3.5mL/gal seemed to stop the progression.

The leaves I posted originally have darkened up considerably! I can't help but think it had something to do with the 48 hour darkness. From what I can tell I have some pretty happy plants - just hoping I can keep it together for a few more weeks.



Cheers

 

[MedGrower]

Thank you for taking a look! Any suggestions on a suitable Mg-only supplement? I've only ever run Calmag all the way through, would lowering the dose a bit work? This is my second coco grow, first one had a lot of issues at about 1-2 weeks further on and upping the Calmag to 3.5mL/gal seemed to stop the progression.

The leaves I posted originally have darkened up considerably! I can't help but think it had something to do with the 48 hour darkness. From what I can tell I have some pretty happy plants - just hoping I can keep it together for a few more weeks.

View attachment 1181210View attachment 1181211

Cheers

Very good news! It may have just had some hard time after the dark period to adjust and now got over it. Great!

I've used Canna MONO Mg for when I've needed Mg only but these days I really am a big fan of Remo Nutrients and their "Nature's Candy" has both Mg and Iron in it and works great for generative period. Basic feed already includes some Ca in their Micro nutrients so they also balance out nicely.

Keep in mind that its good to maintain a healthy balance between Mg, Ca and Iron since too heavy disproportions can lead to problems. My rule of thumb is though: Pronounced need for Ca in vegetative stage and pronounced need for Mg in generative. Quite straight forward

All the best and hope you have a smooth ride to the end. Seems like you will!

 

[Moose8810]

Thanks for the suggestions, sorry for the delayed reply - life's been crazy. I'll check those out, not sure if I'll be able to get any before this round is over. Pretty smooth sailing since my last post, however some new stuff is coming to light and rather than starting a whole new post I figured I'd keep this grow to this thread.

~3 days ago, I noticed some yellowing on some of the uppermost 5-fingered leaves on one cola on one plant. I've also got some red petioles scattered around. The red is showing on all the plants, all in the top of the canopy and only the top half of each petiole. All the lower petioles are nice and green, and after a little reading I've been thinking the red top half of the affected petioles is from the lights. But now with some interveinal chlorosis on this girl I'm thinking I may have some other issues brewing.

Same conditions as the original post, plus 2 more 3500K Autocobs. Still using GH Trio, though I've been upping the EC as they've progressed over the last couple weeks.

Going into each 5gal bucket I mix up currently:
15mL Calimagic (what I've got on hand, ran out of Calmag+)
16mL Micro
32mL Bloom
5mL GrowthTech Ionic PK Boost (ran up to 10mL but got a little tip burn as you can see in the pics)
5 drops Hesi SuperVit
10mL Liquid Karma
10mL Sensizyme

I also hit them with Recharge yesterday. Feed input tonight was 1.5EC/5.9pH, runoff into a clean tray was 1.6EC/6.0pH. Using a Bluelabs Truncheon to measure EC.

62 days old today, lights are 12-14" from the tallest colas - can't hang them any higher, the affected cola is one of the tallest. Any idea what I'm looking at @MedGrower @Waira ? All pics are lights off with flash, not sure if the limey green comes through sufficiently - it looks worse to my eye.

 

[Waira]

Looks light blasted to me.... you should consider supercropping that cola, 12-14" is too intense with COB's... A Q-board you may get away with it because the light is far more diffuse over a wider area..

 

[Moose8810]

That's what I was worried about. Any tips on supercropping her without doing serious damage? Did not expect these to get this tall!

 

[Waira]

Well, I'm no expert, so read up on it here and around,... last time, basically it was kinda like felling a tree, you gotta pick where you want the top to lie; then you start gently squeezing/rolling the main stem to soften it up some before bending; usually the stem is hollow, so it's not hard at all, you just must be careful not to wrench the thing down and snap it... I put a pencil against the stem below where I wanted to kink it, then bent it down over the pencil.. it should kink readily, do it just enough to get it to lay over about 90 degrees.....

 

[Moose8810]

I ended up kinking a few of the colas, tied a few others down. I didn't want to risk bending them over too low, they're all pretty woody and I didn't want to snap any. Also took down all the ratchet hangers on the lights and zip tied them all to the ceiling of my tent - gained a good 3-4" in addition to the height gained from the supercropping/tying. Colas closest to the lights are around 18-20" now, scorching seems to have stopped but I'm still a little worried they're too close.

Thank you for the input, think I'm going to be running fewer plants in the future so I can spread them out a bit more