Yellow tips, blotchy yellow spots - Nutes, light, or fungus?

[Lil Dab]

Tutorial - A word on Nutrients

The proper use of “salt” based fertilizer to grow Auto Flowering Cannabis. Salts: Natural and man made any chemical compound formed from the reaction of an acid with a base, with all or part of the hydrogen of the acid replaced by a metal or other cation. Learning how to use salt based...

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Tutorial - Quick and Dirty Deficiency Guide. With photos

:toke: Folken- This thread is for compiling various deficiency pics gathered from all around,... the idea is to get several pics of each defc. and it's various symptoms, particularly the more atypical ones,... hopefully, to be included in a more comprehensive, consolidated thread for staff...

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[Kazooey59]

Here is an "inside view" into the plant. All the growth beneath the canopy is 100% healthy, new or old. This is confusing. Ignore my feet by the way, they ain't free.

But what is also confusing is, that I haven't used my PAR meter in a few weeks, as I.. lost it. So I opened up my Photone app as usual (s21 ultra, it is usually fully calibrated to this phone), and they made an update so I have to use a diffusor now.

I just checked the PPFD, and they were at over 1000PPFD at 20/4 cycle, which translates to a DLI of 72. This seems like a lot, or? I feel like something is really off here, and it might not be the nutrients at all. As you can see in the video, all the growth is just fine beyond the canopy, it's all green, light tip burn here and there because of high EC, but that's about it. As soon as you view the top canopy though, all leaves are crispy yellow, burnt and blotchy everywhere, curling upwards here and there.

As far as I know, deficiencies or toxicities always show on ALL the leaves, either new to old, or old to new, starting somewhere, and then spreading. but in this case, it's literally just the canopy as of 3 weeks ago. Did I really just burn them because my app wasn't calibrated correctly? The light charts for this lamp are also not made for this, as they recommend 100% at 12/12, which is fine, considering that around 1300PPFD at a 12/12 cycle should only be around 56DLI, which is totally fine for photoperiods. I heard a DLI of 45-55 is the max for autos without CO2, usually needing CO2 at 50+ DLI.

Did I really f this up because of my funky app? Was this the ghost I chased?

 

[Bruce Campbell]

Looks like a K issue.

Canna A + B has a ratio of about 1:2:1 for K:Ca:Mg on its own. I try to keep those in a 4:2:1 ratio.

So, my guess would be high Ca locking out K.

I'd remove the calmag and somehow increase K (without adding extra Ca). Potash may work, but is high S, so it may not be the best long-term / permanent solution for reservoir applications (and/or have other compatibility issues). If you then continue to have Mg issues, I'd try using epsom salts instead of calmag (but with same caveat on S).

 

[Kazooey59]

Looks like a K issue.

Canna A + B has a ratio of about 1:2:1 for K:Ca:Mg on its own. I try to keep those in a 4:2:1 ratio.

So, my guess would be high Ca locking out K.

I'd remove the calmag and somehow increase K (without adding extra Ca). Potash may work, but is high S, so it may not be the best long-term / permanent solution for reservoir applications (and/or have other compatibility issues). If you then continue to have Mg issues, I'd try using epsom salts instead of calmag (but with same caveat on S).

Problem is that I'm using RO + Tapwater, my base EC is at around 0.1, which I then raise to 0.6EC with canna calmag agent, as I otherwise had heavy magnesium deficiencies, and with less than 0.4EC of Calmag, also severe calcium deficiencies.

What would your recommendation be here? Maybe Calmag until I hit 0.4EC, and then Magnesium / epsom salts? But how much, I'm still a bit new to the synthetic world of nutrients

 

[Mañ'O'Green]

Top leaves is the clue here that it is the immobile nutrients most likely the problem here almost impossible to say if iron or zinc. Give a shot of Earth juice Micro Blast.

Be sure your inputs are PHed to 5.8.

 

[Mañ'O'Green]

Problem is that I'm using RO + Tapwater, my base EC is at around 0.1, which I then raise to 0.6EC with canna calmag agent, as I otherwise had heavy magnesium deficiencies, and with less than 0.4EC of Calmag, also severe calcium deficiencies.

What would your recommendation be here? Maybe Calmag until I hit 0.4EC, and then Magnesium / epsom salts? But how much, I'm still a bit new to the synthetic world of nutrients

It is not light burn!

Use Canna schedule off their website precisely, you do not need extra calmag with their products.

Good luck!

 

[Kazooey59]

It is not light burn!

Use Canna schedule off their website precisely, you do not need extra calmag with their products.

View attachment 1699876View attachment 1699877


Good luck!

Thanks for all the input!

I talked to canna already because of a magnesium problem early on, and they blasted me for using straight up RO water. They told me to use Tapwater + RO water, around 25/75 tap/ro, and to raise my calmag ratio to 0.4-0.45EC to not cause any problems. I use RO because my tapwater is insanely unstable with PH, I learned not to use it raw by past experiences.

I did use 0.4EC as base calmag solution + nutrients afterwards, but had severe magnesium problems. I then raised calmag to 0.6EC, and all the problems disappeared. They told me to never ever use Canna Coco A/B without Calmag if I use RO water, which is why I always add that stuff first, and nutrients afterwards.

I swear by the schedule, but always add my base EC of 0.6 including calmag with the custom water EC, and go by that, because as soon as I go lower than 0.6EC, I get heavy magnesium deficiencies all over the plants. Even now I still have very light magnesium issues on a few leaves, but around 99% less worse than it was before.

Top leaves is the clue here that it is the immobile nutrients most likely the problem here almost impossible to say if iron or zinc. Give a shot of Earth juice Micro Blast.

Be sure your inputs are PHed to 5.8.

View attachment 1699871

Just so I understand correctly - Do lower **new** leaves not count? I made a video about this plant, showing that it's totally healthy on all the newest and oldest leaves beneath the canopy, it's just the very top of the canopy showing these symptoms. I thought symptoms show on all new leaves, as they don't just grow on the top, but everywhere. Is this wrong information I got? I wanna understand this problem correctly, so I don't cause any more trouble.

I was focused on lightburn because not one leaf beneath the canopy is damaged, be it old or new growth, buds with new leaves, they are all 100% healthy. It's only the very top with these crispy yellow blotchy leaves

EDIT:

I flushed one of them. I did it, just to make sure everything is actually in check.

These plants are currently receiving 2.4EC of feed 24/7 in autopots. Flushing isn't recommended at all, but whatever. 120L with a 0.8EC solution at 5.8PH got blasted through the pot, just to make sure the salt-layer is fully flushed out, as there never is any runoff otherwise.

Here is the weird thing - The EC never spiked at all. It didn't matter how much flush-feed I poured in, the EC kept being at around 0.7-0.8EC, even though they were feeding on 1.6EC by day 15 already, only rising upwards without having runoff once.

The other weird thing is the PH - The plant measured a runoff PH at around 6.45PH. Now this is the problematic thing, because most people say that runoff PH is worthless. My plant is showing severe symptoms though, so is this something I should go deeper into? I flushed with 5.7-5.8PH, but the runoff PH kept stable at around 6.4-6.5, not budging one bit.

Just wanted to mention this!

 

[Bruce Campbell]

Have you hit the 'Generative Period II' stage in the chart that includes the P/K yet?
That could be the shot of K that Canna uses to smooth out cation ratios - you may just need it a bit earlier and/or longer than usual.

Earth juice shouldn't hurt anything and may be worth a try. Your 25% tap water, the early onset (originally ~day 30-ish), and tip-inwards progression makes me think it's not a micro issue, but I wouldn't rule it out. Just be aware that micro issues can be slow to resolve, so it may take some time to see whether or not it's working.

Is this your first grow with Canna? Were the Mg deficiencies earlier in this grow, or in a previous grow? These guys are around day 60 right now?

 

[Kazooey59]

Have you hit the 'Generative Period II' stage in the chart that includes the P/K yet?
That could be the shot of K that Canna uses to smooth out cation ratios - you may just need it a bit earlier and/or longer than usual.

Earth juice shouldn't hurt anything and may be worth a try. Your 25% tap water, the early onset (originally ~day 30-ish), and tip-inwards progression makes me think it's not a micro issue, but I wouldn't rule it out. Just be aware that micro issues can be slow to resolve, so it may take some time to see whether or not it's working.

Is this your first grow with Canna? Were the Mg deficiencies earlier in this grow, or in a previous grow? These guys are around day 60 right now?

Hey Bruce,

No, I haven't hit Stage 2 yet, no PK booster added so far, because I am scared of a K toxicity as mentioned.

Earth juice sadly doesn't exist here, I'm from Germany. About the micro issue - Yeah I don't know. I imagine all the immobile stuff will be visible from the top, but i'm still confused as to why it's only happening on **the top** canopy. I remember having micro / immobile issues back then, and it started on the top and also n the bottom, but only on the newest growth / leaves. This time it's just the top canopy, while everything below is healthy and thriving.

Something else I have noticed - The trichomes on top disappeared, pretty much the "frost". It's only beneath the canopy where all the leaves are healthy.

This is my first official canna grow, yes! The MG deficiency started at around day 5-7 after sprout, and kept appearing until around day 20, at which point I have raised my base EC all the way to 0.6 with calmag (0.1ec because of tap mixed into my water, 0.5 calmag). This is where the mag deficiencies slowly disappeared. As of that day, it's all 99% gone. Heavy mag deficiency at around 0.45EC of calmag, heavy cal/mag deficiency at around 0.3EC of Calmag, so 0.6 was the sweetspot.

And yes, they just hit day 60 since sprout, with 2 of them probably having around 20-30 days left, while the other 2 (including this funky one) still haven't even hit the bulking stage, just lots of pistils for now. Probably at least 30-40 days for them

 

[Bruce Campbell]

First - It's not unusual to sorta 'limp' across the finish line at harvest with ugly looking fan leaves. Most growers accept some yellowing (or worse) since you're pulling those leaves off at harvest anyways, as long as it doesn't get into the buds themselves.

As far as micros - Earth juice is basically a micro-only / micro-focused supplement intended for hydroponics - anything similar would work. You'd be looking for something with at least Zn and Fe on the label, and as little N-P-K-Ca-Mg as possible. Then, I'd probably say use about 1/4 to 1/2 strength of manufacturer's directions.

But, overall, it sounds like your plants may just be hungry for that P/K - not the other way around. That is, I'd be more concerned about a K deficiency than a K toxicity at this point.

Although there's a tolerance on the range and you don't need to hit the ratios exactly, a general rule of thumb is to provide K:Ca:Mg in a 4:2:1 ratio by weight. You can't really determine the relative ratios by EC alone - you have to go back and calculate/ballpark it from the label wt% of each element for each product that you're adding.

Canna A+B is 1:2:1, and the calmag would make the K:Ca side worse (even if it fixes the Ca:Mg side). Looking at the Canna feed schedule, reports from others pre-stage 2, and the fact that feeds for coco grows generally tend to be high Ca, it looks like Canna kind of rides the edge of low K / high Ca until the hit of K from stage 2.

As far as previous Mg issues, seedlings are more sensitive to feed variations than the adult plants. If you were having Mg issues during seedling, they may not (or take longer) to reappear now. And, I wouldn't worry too much about the upper vs. lower canopy distinction. It may just be an artifact of indoor growing vs. outdoor growing.

In the end, you may just be stuck with having to alternate calmag on/off during the grow until stage 2.