I am looking for input from experienced commercial growers.
I have been growing cannabis for 19 years and 6 of those years on a commercial scale.
I am a botanist and horticulturalist by training. At our farm we try to take a scientific approach to problem solving. This problem is big, has come on fast and requires as much information gatherning as possible.
I have encountered many hermaphrodite issues over the years, but this one is different.
We are having a sudden surge of male flowers growing on strains that have never done this before.
I am growing in 6 large indoor flower rooms (1200sqft each) Our farm has been using these rooms for over 1 year now quite sucessfully. We grow 12 strains in each room and cycle through 48 strains in total. We grow in climate controlled rooms under mixed DEHPS and CMH lighting in a hybrid of rockwool and coir media. Nutrients are Jacks 5-12-26, calcium nitrate, monopotasium phosphate and potasium sulfate. Run-to-waste pressure compensated drip irrigation. We monitor pH and EC of feed, effluent and media regulary. All trays have on-table ducting that blows filtered air up through the canopy.
In the past 8 weeks we have had a shockingly huge number of plants herm on us.
And when I say herm, I don’t mean stress induced bananas forming on the top flowers at the late stage of flower. No, this is happening on the underside of the canopy separate from the female inflorescence. It’s also happening at weeks 3-5 to plants growing in seemingly great environmental conditions. I typically grow batches of 100 plants per strain (1 plant/sqft). Over the past 8 weeks I have had to remove plants from 3 different rooms totaling over 500 plants.
These male flowers look similar to hermaphrodites I would cull from a pheno hunt. These are not pheno hunt plants. 50-75% of the plants from a strain batch will develope male flowers within a week timeframe. So we have to kill the batch. Additionally I have found dozens more plants in these rooms doing the same thing, but only a few plants in the batch will do it.
The first time we saw a batch herm it was with a strain that was on its first production run. We thought we had just missed the trait in the pheno hunt process. Then came batch after batch of strains we have been growing for years with no issue. One OG Kush strain I have been growing for almost 10 years had 100 of 100 plants grow male flowers. Ive seen this cut develope a few bananas in stressful conditions in late flower, but this was week 4 and all of them with male flowers under the canopy.
So this is a pretty big problem.
Checked all the usual things. Heat stress, light stress, light leaks, lights turning on at night. Nutrient stress. Nothing obvious.
About half way into this 8 week period we start to see some possible nutrient deficiencies. At first it looks like Nitrogen and maybe a little Calcium. We bump up those two elements in the feed but no response from the plants. The yellowing continues along with brown splotches that look almost like pesticide burn.
So we have come up with a hypothesis on the yellowing and hermaphrodite issue. If anyone has heard of hermaphrodite induction for this reason I would love to hear about it, because I have not heard of this happening.
CHLORINE TOXICITY: The most significant change we have seen in the time-frame of this issue is the Corona-virus. We have started bleaching walls, the edges of trays, doors and table handles every day to keep workers safe from the virus. Historically we have been cleaning under canopy table-ducting between crops with isopropy alcohol. Since isopropyl alcohol has become scarce we began doing our post harvest table-duct cleaning with bleach instead. The idea is this daily addition of bleach from wiping and possible bleach residue from the duct being blown constantly on the underside of the canopy could be causing stress leading to hermaphrodite problems. The location of the male flowers on the plant fits well with this idea. We don’t have any evidence that chlorine causes hermaphrodites, but we know it could be causing stress, and stress can cause male flowers to form. Also possible that bleach contains metal impurities such as silver, a known cause of hermaphrodism. The possible Nitrogen and Calcium deficiencies we have been seeing have not responded to increases in these nutrients as we would have expected. As the issue has continued it looks less like N and Ca deficiencies. What it does look like is chlorine toxicity. See pics below.
We cannot say definitively that this is the problem. We have stopped using bleach in the rooms and we have removed any duct that has been bleached. We have wiped all bleached surfaces and now sanitize with hydrogen peroxide. If this is the problem, we do not know if this could be a delayed reaction and we might still see this issue for a little while.
So now that I have probably bored half of you into reading something else, I ask for input from those who powered through.
Has anyone heard of this problem being caused by chlorine?
Has anyone had this happen to plants that have no history of herming?
I am open to any possible area of discussion relating to this problem.
Other factors that could play into discussion: This building was once a metal fabrication shop on half and a cabinet manufacturer on the other half. We have tested product for heavy metals and never found anything unusual. We use compressed CO2 instead of CO2 generators so there is no combustion in the building.
If you have any ideas I am all ears.
Thanks for your participation