What is this affliction?

[Jatzan]

Plant is about 2 weeks into flower, 10 weeks in total.
Medium is soil mixed with a bit of coco and vermiculite, surrounded with hydroton, sitting in 3gal fabric pot with proper drainage (not touching the bottom of the pot). The amount of soil is less than 2g.
Watering is about a quart every 2 days. Fed only 4-5 times with 0.5 EC at veg, now upto 1.2 max. PH is always around 6 when watering/feeding. Tap water has huge EC so I am using: 3/4 RO and 1/4 tap water amended with epsom salt to keep the early mag def in check (i used to have it on around week 6).
The environment is 72F during lights off and 82F during lights on, keeping proper VPD all the time with 50-65% RH as needed.
Light is LED, it is quite far but powerful enough, current schedule is 14 on/10 off because the plant is autoflower (this was reduced from 18 on/ 6 off during veg).

I noticed the bottom leaves first turning brown and mushy, not on the edge, but close to it.

Then the brown and mushiness goes to the edge.

And finally the brown of the leaves turns dry and crispy (see the leaves in the back).

 

[Jatzan]

Images didn't load:

I noticed the bottom leaves first turning brown and mushy, not on the edge, but close to it.




Then the brown and mushiness goes to the edge.



And finally the brown of the leaves turns dry and crispy (see the leaves in the back).

 

[hotrodharley]

I’m going go with root issues here. 2 gallons of soil that includes coco? And why vermiculite which retains moisture when everything else you’re doing promotes quick drainage?

 

[Jatzan]

I’m going go with root issues here. 2 gallons of soil that includes coco? And why vermiculite which retains moisture when everything else you’re doing promotes quick drainage?

Why would there be root issues when everything is set for quick drainage and I used to water it once every 3-4 days until recently. It can have a bit of runoff but it is never drenched for long.

There is only a small amount of vermiculite that has a double purpose:
1 to prevent complete microorganism death when the soil is dry (and we want a bit of dry for root growth)
2 it is a bit of a ph buffer and creates a microspot of higher ph (one that is alkaline upto 7.5ph but only locally). When breaking down the sugars, the microorganisms can create a bit of an acidic environment so I dont want that.

I might be wrong, but that is my reasoning ¯\_(ツ)_/ ¯

 

[hotrodharley]

Why would there be root issues when everything is set for quick drainage and I used to water it once every 3-4 days until recently. It can have a bit of runoff but it is never drenched for long.

There is only a small amount of vermiculite that has a double purpose:
1 to prevent complete microorganism death when the soil is dry (and we want a bit of dry for root growth)
2 it is a bit of a ph buffer and creates a microspot of higher ph (one that is alkaline upto 7.5ph but only locally). When breaking down the sugars, the microorganisms can create a bit of an acidic environment so I dont want that.

I might be wrong, but that is my reasoning ¯\_(ツ)_/ ¯

A lack of space for the roots. Again 2-gallons of fill in a 3-gallon bag. Quickly drained or not

 

[Jatzan]

A lack of space for the roots. Again 2-gallons of fill in a 3-gallon bag. Quickly drained or not

Well, on the bright side, theres a gallon space left in the pot for the roots xD

 

[VRZ711]

P defecancy, or P intake is blocked by excess of other elements.
PS: I keep my autos 20/4 all the way.

 

[hotrodharley]

Well, on the bright side, theres a gallon space left in the pot for the roots xD

Personally I keep containers filled to the top including adding as the medium compresses with age.

 

[Jatzan]

P defecancy, or P intake is blocked by excess of other elements.
PS: I keep my autos 20/4 all the way.

This might be part of the problem, I will try upping P. I don't think I have an excess of the antagonists of P. Thanks for the advice!

Btw I think I might be facing a Boron toxicity also. I found out that one of the nutes that i fed twice at low EC is actually for boron deficient soil. And it has A LOT of boron. I am an idiot. But the label didn't help at all, you have to read the "fine print" to understand that it has a lot of boron.
I also found this thread: https://www.icmag.com/threads/boron-toxicity-in-cannabis-images-and-info.213473/
The leaves look exactly the same!

I don't know if I can ride out this boron toxicity (with leaves absorbing it, dying and cleaning the soil) or maybe I should start thinking about repotting.

 

[Jatzan]

Personally I keep containers filled to the top including adding as the medium compresses with age.

This is good advice, but I cant do it with this plant, because of the LST training on this plant. The main trunk of the plant is almost touching the hydroton on top, so I cant add soil without it touching the trunk Next time

 

[VRZ711]

(with leaves absorbing it, dying and cleaning the soil) or maybe I should start thinking about repotting.

just give water , then start ammending other nutrinets