Diagnostic and treatment help needed please.

[BR2K]

Could your lights be going on the fritz? What's the humidity in the room? Is it stable? Grasping at straws, I know.

[Serapium]

BR2K i have already sacrificed a half dozen plants to examine the rhizosphere in minute detail. No obvious aberrations.

[Serapium]

Daskahn i use clonex, same stuff I've used for years with great success. Same cloning technique I've been using with 92-95% success rate for years running.

[Serapium]

BR2K yes these are all clones taken from known good healthy mothers. Some of the mothers were acquired as clones and others were started from seed. Almost all these clones were taken from 1st Gen moms or were propagated from 2nd Gen clones.

[Daskahn]

My questions and I apologize if I missed it.. but what type of cloning gel are you using?
and are these autos or non autos?
main observations of mine.. your clones seem to large.. and to many nodes left on them.. my rule of thumb is.. the newer the growth node you us for clone the better the success also if you remove all but the top and reduce the stem they do better.. but I’m not an expert on cloning

[BR2K]

Are all of your plants clones? How many generations? Please bear in mind, I'm a newbie - I'm just trying to brain storm here...Perhaps you'd be willing to sacrifice the worst specimen to examine the roots?

[Serapium]

Symptoms are NOT present in all plants. Symptoms are present in some specimens of every strain in the library, but not every specimen of any single strain. These plants are in the same room with the same growing parameters and techniques, taken at the same time from the same mother plants.

Also, I manage several different grows in different geographic locations. This is the only location exhibiting these symptoms.

[Serapium]

@bt2k nothing changed. Same grow techniques. Same IPM procedures. Same environment, nutrients, pH values, feed rates, lights, etc. Plants just started doing this one day with no obvious alteration in growing parameters.

[BR2K]

Since you're much more experienced than I, my only advice is to ask - What has changed? New pet? New person (not cannabis friendly)? Any other new variables, such as new grow tent? Good luck!!!

[Serapium]

Ok, so let me begin by saying I'm not new to the game. Been around a while, and while my knowledge is far from comprehensive I know more than most when it comes to growing cannabis (largely thanks to years of research in wonderful groups like this, reading books, hands on instruction from people with decades of experience, and personal experimentation.) With that said, I'm currently stumped.

I cut a bunch of clones from several very healthy mothers that are proven good genetics from a years long pheno hunt. These plants have been taken to successful harvest several times, with excellent health and wonderful end results.

Those clones started out healthy, but as they age they're showing some truly awful signs of stress that I can't identify.

I've been fighting this for about 6 weeks now and have exhausted my ideas and those I've found through research.

Growing parameters:
Coco
Cloth pots
GH 3-part at 1/3 strength
Using RO water
Supplementing with CalMag
Ph to 6.0 to 6. 1
Temps in low to mid 70s
Humidity 50-60%
Some plants under LEDs, some under CMH, some under HID. Ppfd at canopy ranging from 400 to 800 at various times trying to identify any light issues.

I've examined plants under a microscope and find absolutely zero evidence of pests of any kind.

They are not being over-watered. I have tried various levels of both nutrient density and feeding amounts. Various combinations and ratios ranging from 400ppm to 1100ppm and anywhere from a quart a day to a gallon a day.

Runoff tests good, with pH and ppm coming out where they should.

I have flushed repeatedly with straight water to full runoff a couple of times.

I've experimented with a few and let them dry out almost completely.

I've treated with several beneficial innoculants, both bacterial, enzymatic, and fungal.

I've used a couple of natural foliar sprays, including a neem based product, an all-natural organic plant-oil product, and a sulfur based product. I even went nuclear on a few in quarantine with hard core chemical insecticides (and when that didn't have an effect I discarded the plants.)

I've changed pH up and down on a few. I've calibrated my pH meter, and then also double checked for pH accuracy using drops and strips. PH is being raised and lowered with both natural and chemical means on different small test groups (vinegar, lemon, and baking soda to commercial GH up/down.)

The pictures attached show the various stages of progression as the clones age.

Suggestions? Today I'm trying a solid flush with H2O2, but that's the last thing I have to try.

This is in a commercial facility, and I have sought advice from multiple experienced 'master grower' type people whose opinion I highly value, and tried their suggestions with no effect.