Unusual leaf browning

[abominableSCOTT]

-Problem: unusual leaf browning 21 days into flower happening on middle of the shade leaves and around some of the bud sites. not from the bottom up or visa versa
-Medium/grow method: Coco coir (Moonshine brand) mixed with perlite
-Feed and supplements used: Fox farms tiger bloom 4 teaspoons per gallon along with 1 teaspoon of CalMag.
-Water source: PH in 6.5-7 PH runoff 6-6.5 Colorado Well Water

-Strain and age 90 day old plants hybrids
-Climate: greenhouse grown 68-88F temps with 40-70% humidity
- Light used: diamond 300W LED on 12/12 timer. 12-18 inches from canopy
-Additional info: started showing 1-2 days ago.
--Pictures

 

[Waira]

--- I think you have some nute burn/toxicity-salt build-up happening here,... Coco is very different that a true soil, and can't be treated like it,... lot's of do's and don't's! So, are you familiar with coco growing? Is this in a stand alone pot, or a feed system pot? If a solo pot, are you doing 15-25% run-off every time? The nutes dosage is too high, even for soil, but in coco, it's a recipe for disaster,.. cumulative inputs will begin to build up, leading to lots of problems,... Also, the pH is too high all around,... in-pot pH should be about 6.0,.. coco growing has more in common with hydro than true soil basically,... straight run-off testing for pH is not an accurate measure of in-pot pH, you'll need a good pH probe for that,... usually in coco, you measure your inputs pH and ppm/EC, the measure the last of the run0off for both to see where your build-up levels are, and if the pH is drifting off range,..... very likely you'll have to flush the pot, and in coco, that's also done differently than soil or peat based soilless,... due to coco's weird CEC properties (cation exchange capacity), namely the way it strongly binds Ca, and Mg to a lesser extent, the levels of those need to be maintained, or if too low, the roots can't 'peel" that Ca/Mg off the particles, it won't release until the sites are sated, then it'll start to give and take,.... to preserve this balance, it's recommended to use RO/Di water, with 150ppm Ca-Mg, plus another 150ppm nutes, pH to 6.0,... pour through until the run-off is at or near input values,...2-3x pot volume typically,...

 

[abominableSCOTT]

--- I think you have some nute burn/toxicity-salt build-up happening here,... Coco is very different that a true soil, and can't be treated like it,... lot's of do's and don't's! So, are you familiar with coco growing? Is this in a stand alone pot, or a feed system pot? If a solo pot, are you doing 15-25% run-off every time? The nutes dosage is too high, even for soil, but in coco, it's a recipe for disaster,.. cumulative inputs will begin to build up, leading to lots of problems,... Also, the pH is too high all around,... in-pot pH should be about 6.0,.. coco growing has more in common with hydro than true soil basically,... straight run-off testing for pH is not an accurate measure of in-pot pH, you'll need a good pH probe for that,... usually in coco, you measure your inputs pH and ppm/EC, the measure the last of the run0off for both to see where your build-up levels are, and if the pH is drifting off range,..... very likely you'll have to flush the pot, and in coco, that's also done differently than soil or peat based soilless,... due to coco's weird CEC properties (cation exchange capacity), namely the way it strongly binds Ca, and Mg to a lesser extent, the levels of those need to be maintained, or if too low, the roots can't 'peel" that Ca/Mg off the particles, it won't release until the sites are sated, then it'll start to give and take,.... to preserve this balance, it's recommended to use RO/Di water, with 150ppm Ca-Mg, plus another 150ppm nutes, pH to 6.0,... pour through until the run-off is at or near input values,...2-3x pot volume typically,...

Thanks for the very detailed answer. This is our first real grow in coco... we have the plants in solo pots with run off. We will start with your suggestions. We did a PH flush the other day and it appears that it hasnt spread since we posted this. The shade leaves that were affected are toast unfortunately... I will keep you posted and thanks a million for your professional help!!!

 

[All I HAVE]

Is this the same thing I'm seeing.

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