Nute Burn?

[AJrexxx]

I think this is nute burn not sure though. Second opinion would be appreciated.

Growing coco 70/30
Temps running 74-65 degrees
Using flora nova grow & cal mag (2ML cal mag per gallon). Bumped up to 400 pm and noticed this on one plant.
It is a Nirvana Blueberry Kush.

Other plants look fine look fine. Below is a picture of my Nirvana Norther lights I have 2 going neither are showing any issues.

I am growing two Sour Diesel as well, but did not any picks. One of them has 2 of the rust spots on it, but none of the damage at the tips like BB Kush does.

Thanks in advance.

 

[AJrexxx]

Well I guess my self diagnosis was all wrong. Went into my tent this morning and the spots had doubled. Looked at the post that @TRED made realized I had similar spots. I have been doing 2ml per gallon of Cal Mag so did not think it could be a cal deficiency. Well back to basics I went, it finally dawned on me to check my PH meter. Calibration was way off was reading .4 high so I thought I was phing to 5.8 was actually coming in at 5.4 (a little low from what I understand.)

@jingo mentioned a foliar spray so I did that dumped my nutes and made a new batch hopefully that fixes the issue.

Just curious if my PH is that low why did it only cause issues with two of the plants? I have two sour diesels and it only happened to one of them.

New picture...More damn spots.

 

[jingo]

For some reason images didn't show for me. To answer your question, when you mix soil in smaller batches you can get less consistent buffering between pots.

pHing water is foreign to me when using soil, that's why I recommended the foliar it won't mess up soil.

If your input pH is to low your plant won't uptake enough calcium from the soil, so you have confirmed the diagnosis.

 

[AJrexxx]

For some reason images didn't show for me. To answer your question, when you mix soil in smaller batches you can get less consistent buffering between pots.

pHing water is foreign to me when using soil, that's why I recommended the foliar it won't mess up soil.

If your input pH is to low your plant won't uptake enough calcium from the soil, so you have confirmed the diagnosis.

Thanks for the reply I will load the pictures differently tonight.

 

[AJrexxx]

@jingo Here are some pics in a different format. Some new growth cam in and the tips seem to be showing the same signs. My PH is now right so I guess I keep watering and hope it recovers?

@Waira I was told you might be able to assist.

Thanks in advance.

 

[Waira]

Hey AJ'- yeah, pH dipped a bit low there,... possible sub-lockout of P, from those broad interveinal necrotic patches,... (BTW, just to eliminate, that leaf isn't lying low and getting splashed is it?)... Between the pH drop and the mild nute burn on the tips she might be feeling a bit cooked too,.. the feeds bring the acidity, not just from the solution itself, but roots and 'crobes can influence as well,... coco is a bit tricky of a medium, and if you're new to it, I recommend using a coco-specific line which will help deal with it's unusual CEC properties...
I think an in-pot pH test is called for; if you don't have a good pH probe, then do the run-off test method, which can be iffy to useless for accuracy if done wrong,.. here's a link to an improved method and calculation- ( https://www.autoflower.org/threads/...-for-run-off-testing-and-ph-estimation.41733/ ) If you can, get me a TDS or EC reading of the run-off too please, just to see what kind of load is in there,.....From what I gather of our best coco-nuts here, they run high 5's to low 6's pH.... Meantime, ease off the nutes a bit, watching those tips for halting of burn progression, if they haven't stopped yet, but stay on the Ca-Mg,; pH at 6.0,... what's you water source? If it's too acidic in there, a flush is called for, which needs to done a bit differently from soil,...

 

[AJrexxx]

Hey AJ'- yeah, pH dipped a bit low there,... possible sub-lockout of P, from those broad interveinal necrotic patches,... (BTW, just to eliminate, that leaf isn't lying low and getting splashed is it?)... Between the pH drop and the mild nute burn on the tips she might be feeling a bit cooked too,.. the feeds bring the acidity, not just from the solution itself, but roots and 'crobes can influence as well,... coco is a bit tricky of a medium, and if you're new to it, I recommend using a coco-specific line which will help deal with it's unusual CEC properties...
I think an in-pot pH test is called for; if you don't have a good pH probe, then do the run-off test method, which can be iffy to useless for accuracy if done wrong,.. here's a link to an improved method and calculation- ( https://www.autoflower.org/threads/...-for-run-off-testing-and-ph-estimation.41733/ ) If you can, get me a TDS or EC reading of the run-off too please, just to see what kind of load is in there,.....From what I gather of our best coco-nuts here, they run high 5's to low 6's pH.... Meantime, ease off the nutes a bit, watching those tips for halting of burn progression, if they haven't stopped yet, but stay on the Ca-Mg,; pH at 6.0,... what's you water source? If it's too acidic in there, a flush is called for, which needs to done a bit differently from soil,...

Waria I did a soil test and the PH meter I have says 7ish. It is more than likely not accurate and is junk. I actually don't remember buying the thing probably came free with the garage when I bought the house. So tonight when I have time I will run the method you described above. One question just to make sure I have it right. I am going to run RO water through and not adjust the PH and do not add any nutes correct? Two of my healthy plants have a few of the orange spots similar to the pictures above. I was hoping it was an isolated incident, but I have the feeling it is not. I bought brick coco and re hydrated it i am thinking that i messed something up and that might be part of my issue. Thank you again for the help.

 

[Waira]

... yeah, that reading is dubious! The Accurate 8 is a decent unit for the price; same operating principle, just better made...
... Use your usual water source and pH to moisten up the medium just like it says,... then after that hour, use the RO/DI water to get the test leachate -- reason being, is you want to no further pH skewing inputs at that stage (reason for no nutes as well), you're trying to get the best possible "snap-shot" of the pH in there,.. using RO/DI to pre-moisten it would skew results as well, since that type water has no pH buffering capacity at all, and as such is prone to exaggerate the pH from what's in there already,...

 

[jingo]

Sorry dude, I totally missed you were in coco. Sounds like you're getting sorted.

 

[AJrexxx]

@Waira So i put 5.75 in and 6.72 came out with 480ppm. So if I am doing the math right I am at 6.72.

Do you think this could be caused from me not hydrating the coco properly. I typically put in at 5.7-5.8 and so far the highest I have gone is 400 ppm and I backed off that when I noticed what I thought was burn.

Very lost as to what I should do here.