Greetings all. Looking for advice on a recurring pathology/toxicology problem we are experiencing in a newly constructed licensed indoor commercial grow facility in Oklahoma.
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.
Our first experience with this came in late January on the first plants ever brought into this building. I cut a bunch of clones from several very healthy mothers that are proven good genetics from a years long pheno hunt. Clones from these plants have been taken to successful harvest several times at a different location, with excellent health and wonderful end results - i.e. the base genetics were known to be ‘good.’
Those clones started out healthy, but as they aged they started showing some truly awful symptoms that remain unidentified.
We fought this for about 6 weeks and exhausted all remediation possibilities from my ideas, countless hours of research, and those suggested through communication with hundreds of fellow growers in another forum.
Initial growing parameters:
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
Some plants under LEDs, some under CMH, some under HID. Ppfd at canopy ranging from 400 to 1400 at various times trying to identify any light issues.
I’ve examined plants under a microscope (60x - 180x) 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 small groups with several innoculants: microbial, 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 test set. 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.
My last resort was a thorough flush with a high concentration of hydrogen peroxide sufficient to kill anything living in the root zone.
I have sought advice from multiple experienced ‘master grower’ type people whose opinion I highly value, and tried their suggestions with no effect.
We finally threw in the towel and completely purged the entire facility after a seven week battle - trashing about 1500 plants in the process.
We then sterilized the entire facility to a ridiculous degree. Every single system was disassembled, washed with a soap solution, then a bleach solution, then a hydrogen peroxide solution, and finally rinsed with known clean RO water at essentially zero PPM.
We washed every floor, wall, and ceiling in the facility with bleach water, wiped down every single table, shelf, and counter top, and finally ran a high output ozone generator inside the facility with all air moving fixtures running (ac, fans, dehus.)
We sterilized every single tool, tray, feed line, drain line, and humidity dome in the whole facility using the same protocol.
This was not a minor undertaking. With 10,000 square feet it took a full crew of people a full work week to accomplish.
Finally every system was reassembled and the ozone generator ran again prior to repopulating the facility.
Operating under the assumption that any viral vector had been eliminated, we then sourced ten new healthy clones from a different facility and imported them as our canaries in the coal mine. Those ten plants were monitored closely for ten days, and exhibited vigorous and healthy growth.
At that point we then repopulated the facility with 450 new clones from a known healthy facility that practices fairly strict clean room protocols.
Those plants have been resident within this facility for 26 days now, and up until yesterday were all exceedingly healthy. Lush, green, vigorous growth, and absolutely no signs of any pathogens.
I left the building last night with perfectly healthy plants.
When I came in this morning, approximately 100 plants in multiple locations within the building had developed symptoms identical to those from our first experience.
Plants exhibiting these symptoms were not clustered in ‘groups.’ They are sprinkled around in between hundreds of other plants that remain healthy looking.
We’ve pulled every plant from production that has any hint of symptoms, but given the rapidity that whatever this is blew through our facility the first time I have little doubt that others are likely infected.
Our local ag extension office is unfortunately closed thanks to the covid situation, so my only available resource locally to have tissue and soil samples tested is out of service.
Looking for ideas at this point regarding source, cause, transmission vectors, remediation ideas, or anything else that may help us either save these current plants or keep future replacement plants from following the same trajectory if we have to eliminate this batch of plants as well.
The pictures attached show the progression of the damage.