New views on PM and RH.....

[Diabolical666]

PM thrives in high RH but cannot survive actual contact with water. Best PM defense is to spray plant with clean water during veg. Rain kills PM. PM can live with any RH over 50% and no direct water contact. Until its really takes hold as soon as water hits PM it dead. Make it rain!

I had a helluva pm issue last year..actually it was carried on from the year before and just got worse no matter what i did..it becomes systemic if not treated and irradicated immediatly ime. There seems to be variables like strain, envirronment etc.
I ditched everything and started over this year.
These pm plants were outdoors with serious dry enviro, rained on occasionally as well and the pm still thrived.

 

[ZeusBarks]

These pm plants were outdoors with serious dry enviro, rained on occasionally as well and the pm still thrived.

The stage at which pm can be removed with water is well before the time it is visible. I spray my plants with water in veg for no reason other than to keep them clean. It’s like washing your hands, it won’t cure the flu but it sure does prevent it.

 

[Dr. Who]

Not knowing how you grow, how will you manage the what I will call "transferred transpiration" you say is happening?

You said the increased rh reduced the feed uptake. This means more O2 is being produced while using less food. There must be a breaking point, to now with these plants perhaps there are stores of nutrient, but what about when the high rh is present from the beginning?

I have an automatic programmed exhaust. That will take care of the O2.
This is designed as a part of the cooling system for winter months and for some summer turnover for the O2 factor.

Considering that in the veg area. They get about the same RH as the now bumped up bloom area. I expect no real difference from it that way......Yes, I did know I was doing less feeding in the veg area to start. The reductions are not big but, one of those that over time, will save you $ things....

 

[Dr. Who]

The stage at which pm can be removed with water is well before the time it is visible. I spray my plants with water in veg for no reason other than to keep them clean. It’s like washing your hands, it won’t cure the flu but it sure does prevent it.

The answer I have to that, simple..

I have had far, far fewer PM issues in veg then bloom.
Veg room is always hovering between 68 and 72 RH. In fact the area where the breeding is done has only once in it's lifetime had a PM issue (and that started in the bloom area).
Now the blooms had stayed pretty PM free for a few years. Then, the inevitable happened. Boom, rm #1 was hit and 2 not so much. Beat it down and cleaned up. I mean real sanitizing too. I had another hit in 1, then it seemed that it had almost yearly issues and I kept fighting by conventional methods and lowered RH to the 40% level...seemed to work for a few and then it has come back. Not hard but, frustrating you know.....

This ideal, appears at the outset to be working very well!. The botanical idea behind it is solid. Very solid....I simply did think of that ideal vs the old school conventional cannabis growing 50% or less.
I'm not a "Make it rain" kinda guy.....I see your point yet, you need to realize that my issues were not in veg....I respect Rid very much! I just don't practice that ideal..

What will you do if you get hit in bloom? Not the place (bloom) to be washing down plants....eh? Risking molds?
"Rain" in veg does not stop PM in bloom.....by only doing it in veg.

It is a cool theory but,,,,,,

 

[SSGrower]

I have an automatic programmed exhaust. That will take care of the O2.
This is designed as a part of the cooling system for winter months and for some summer turnover for the O2 factor.

Considering that in the veg area. They get about the same RH as the now bumped up bloom area. I expect no real difference from it that way......Yes, I did know I was doing less feeding in the veg area to start. The reductions are not big but, one of those that over time, will save you $ things....

I dont think I asked the question correctly.

Your answer brings more questions but since it all boils down to environment affecting transpiration its all related, sort of.

On earth O2 and gas concentrations (the atmosphere) are reletively similar and constant. Within "habitable" areas the concentrations range even less. When forcing environmental conditions there are so many variables unless we are using hyperbaric grow chambers it seems impossible to compare individual results, but I digress.

Back to the first question...
If the increased humidity is making photosynthesis more effecient, and is causing a reduced need for water uptake from the roots, as the water is where O2 comes from in photosynthesis not CO2, there would be a reduction in the plants nutrient uptake, unless of course the plant is able to fix the issue by adsorbing or fixing them from the air. There are plants that do this is cannabis one of them? Does the increased moisture content and therfore increased partial pressure of water vapor impact this? What about enhaced CO2?

Or is the plant simply able to adjust? If so there must be a boundry line and line is described by vpd?

Many variables.

Is your exhaust philosophy taking into account measured CO2 and O2 concentrations?

 

[ZeusBarks]

The answer I have to that, simple..

I have had far, far fewer PM issues in veg then bloom.

"Rain" in veg does not stop PM in bloom.....by only doing it in veg.

It is a cool theory but,,,,,,

PM is a well studied disease and it is also well known that prevention is the key. If you can see it at all, even with a loop you are 3-10 days too late to prevent it. From an environmental standpoint PM should actually be more likely to inoculate in veg. when you have lots of blue lights and high humidity.

If you are seeing it in flower but not veg it probably doesnt have anything to do with the rooms, if you have PM spores in one, you have them in the other, shit spreads easy. In veg your plants are small and air circulation is good. When you overcrowd in flower PM thrives. Prevent it in veg and circulate air and it should happen in flower.

You should be clearing the total air voloum in the room at least every 3 or less mins if you have correct air circulation. Some ever suggest every 60 seconds. PM takes min 10 mins to take hold and another 3 days min to infiltrate the leaf, air circulation plus some hygiene should keep PM from ever showing even though your air is likely totally full of it.

https://link.springer.com/article/10.1007/s10658-005-5804-6

https://www.noble.org/globalassets/docs/medicago-handbook/inoculation-growth-foliar-pathogenic.pdf

 

[Dr. Who]

If the increased humidity is making photosynthesis more effecient, and is causing a reduced need for water uptake from the roots, as the water is where O2 comes from in photosynthesis not CO2, there would be a reduction in the plants nutrient uptake,

While the plant is up-taking the moisture slower (less need). Nutrient use is basically the same but, less as far as "pushing" is concerned. I am not adjusting nutrient concentrations. Nor am I expecting a "need" to... In consideration of the time sense the change. I am not seeing anything in the plant that suggests any adjustment of nutrient needed.

There are plants that do this is cannabis one of them?

No.

Or is the plant simply able to adjust? If so there must be a boundry line and line is described by vpd?

Generally you adjust to plant needs. Increasing uptake and nutrient means your "pushing" the plant... That space between Green tips (point A) to a little bit of yellow on the leaf tips (point B) to burnt tips (point C) to burnt leaves (point D). Decreases at each point....The plant does not adjust - you do.

I place that boundary line between green and just past yellowing tips - This is a "for me" choice. The VPD will have more effect on that. The harder you push. And the drier you run...The faster to points C and D, over A and B.

 

[Dr. Who]

If you are seeing it in flower but not veg it probably doesnt have anything to do with the rooms, if you have PM spores in one, you have them in the other, shit spreads easy.

The spores are everywhere. They simply look for the right conditions to begin growth...

Your missing the whole point of what I'm saying in relation to plant structure and it's own ability to repel the attack.....So yes, it does have to do with the environmental conditions in each room.

In veg your plants are small and air circulation is good. When you overcrowd in flower PM thrives. Prevent it in veg and circulate air and it should happen in flower.

Over simplification....Ever seen a SOG grow? That's crowding......

You should be clearing the total air voloum in the room at least every 3 or less mins if you have correct air circulation.

What do you grow in?

For me it's not as simple as that.....Stand alone buildings that draw air from the outside.....Tend to have temp issues when attempting to do that. REAL issues. You have whole buildings being run as grow ops. Now how do you totally over turn the air in a 50,000+ sqft commercial facility, every 3 min, AND hold temps?
Go in a local greenhouse and look around.....How often are they doing it?

I run fans and move air... NOBODY but tent growers "overturn" the air....Anywhere near those times! Fun part of that is.......What if it hits something in the room the tent is in? Like another tent maybe? I can only imagine the horror that would be after a power failure of even 1 day.


At least you didn't bring up the debate on if it's systemic or not......I do NOT agree with the systemic argument....

 

[Dr. Who]

After being out in the room and really looking at the pot moisture content...

I am not getting a reduction in the amount of fluid used to water in any real useful amount....Maybe, and I mean maybe 5%<.
I'll go ahead and say I was mistaken by newly added plants that were still ramping up watering needs.....


I'm paying far more attention to the newly added plants over plants farther in bloom, that have been in the room for some time.
The new plants have less chance of lost cuticle to lower RH and higher heat exposure.
They do show no developing PM issues.

This room will be finished and turned over. In the same note she will get a complete sanitizing and a burn with no plants present...
I will then refill and closely watch plant growth, and for any PM.....

I am not fully convinced this is going to provide a difference but, I am seeing what could be positive results so far. I must compare it to the other room and from a clean start with fresh plants...

Updates as they are needed....

 

[SSGrower]

Standards for pharmaceutical packaging areas range from 4-10 air changes per hour, far less than 20. To keep costs down they hepa and uv filter the air, they bring in as little outside air as possible as it costs more money to condition AND filter it.
IMO one of the most effective things you could do for prevention is filter the air. Standard hvac filters can catch a good % of mold spores. I run an inline duct filter on my recirculating tent vent system.

 

[ZeusBarks]

What do you grow in?

For me it's not as simple as that.....Stand alone buildings that draw air from the outside.....Tend to have temp issues when attempting to do that. REAL issues. You have whole buildings being run as grow ops. Now how do you totally over turn the air in a 50,000+ sqft commercial facility, every 3 min, AND hold temps?
Go in a local greenhouse and look around.....How often are they doing it?

I run fans and move air... NOBODY but tent growers "overturn" the air....Anywhere near those times! Fun part of that is.......What if it hits something in the room the tent is in? Like another tent maybe? I can only imagine the horror that would be after a power failure of even 1 day.

Um im not sure how your going into full power failure, you lost me there. However it sounds like you are growing in an inviroment ill suited for cannabis. Basically your outside air is bad. Sounds like it’s way too hot, which make it weird that you would ever have pm issues. This again points to really poor air circulation.

If you outside it that toxic to cannabis you need to create an artificial outside. Like the top configuration:



If you want to see a real comercial greenhouse go to a big time agriculture operation not some for borderline profitable weed grow. Air gets out of the grow space, normally right outside b/c it is not profitable to a/c food. However if you’re not in a climate that allows that, fake it with a/c. that’s not an excuse to seal a grow space. Sealed spaces mold

 

[BarnBuster]

If you want to see a real comercial greenhouse..

lol, yeah, Doc

 

[ZeusBarks]

lol, yeah, Doc

I never said I ran a commercial al agriculture operation off my yellow pad but fact is even the best cannabis operations in the world have no experience compared to the wine, grain and vegetable industries. For example, lollipop pruning that the cannabis industry think is so cool, is a trick practiced in ancient roman wine vineyards. Humans have been growing plants for 1000s of year, the cannabis industry is less than 100 years old. Basically every type of pot grown now didn't even exists before 1960.

 

[Dr. Who]

Um im not sure how your going into full power failure, you lost me there. However it sounds like you are growing in an inviroment ill suited for cannabis. Basically your outside air is bad. Sounds like it’s way too hot, which make it weird that you would ever have pm issues. This again points to really poor air circulation.

If you outside it that toxic to cannabis you need to create an artificial outside. Like the top configuration:

View attachment 4315272

If you want to see a real comercial greenhouse go to a big time agriculture operation not some for borderline profitable weed grow. Air gets out of the grow space, normally right outside b/c it is not profitable to a/c food. However if you’re not in a climate that allows that, fake it with a/c. that’s not an excuse to seal a grow space. Sealed spaces mold

You don't know me very well......I've been growing cannabis for over 45 years now. I ran over 10 acres of commercial greenhouses in/after college to pay for college. I then was hired by a major US pharmaceutical company to run the whole Yew farm operation to make Taxol...Just to get a grip on how big that was. At one point we had 24,000,000 plants in various stages of growth. That area, covered square miles!

I grew up on a farm, and now in retirement. Run that farm and manage 4 more that created a now 5 farm organic co-op that supplies Produce, Dairy, Beef, Pork, Poultry and now moving the grain ops to Barley and Wheat for organic brewing for use in the two major brewing cities in our state. One has been given the national title of "Brew city USA". We are now expanding into more Hops area's for the same reason.

Outside air is never "toxic" to cannabis.....I grow some outside every year for my personal stash and Christmas gifts...... You make me laugh kid. My "out side air is BAD".....ROTHFLMAO!

I have one of the tightest environmentally controlled grow operations in the area.

All incoming air is HEPA filtered. The op is set up for gassing by CO2 generator(did you know they (mostly) are REALLY portable hot water makers for camping? - Yup, that's where the designs were stole from) I later choose NOT to gas.

Before I wrote this post.....Conditions were set for - Temps of 73 deg F at the therm. level. 45% RH and all strains dialed in on that. Night temp drops are normal... Everything is controlled by environmental controllers with fuzzy logic.

Here's last remaining pic of one 12x24 production room.



That is a "support" the central AC system portable that is online for several months a year.

Each light now has a 400w Merc vapor under it, for added blue and UVB spectral bands. The inside the hood lamps are 1K HPS in Jupiter 6 hoods that deliver 20% more light. They are set at 6ft centers to overlap for one continuous lighting zone of high intensity light delivery - NO WEAK ZONES!

I have no real issues other then in the first building, and then in only one room. I made the dumb ass mistake of not sanitizing before I moved the operation in.... Chalk it up to being too damn excited to move in the new building....

Next thing is "jr".....That you carry spores into any facility that does not have a "blow off" area and shoe cleaning station.....Like a chick breeding poultry operation....They are everywhere. They only need the right conditions to actually start growing....

They got that in mine, this last spring when a storm caused a power failure in our area... Understand power failure now?

I was polite here.....

I won't be next time.

Oh yeah, I grow 4 different types of wine grapes for my own wine making.... I got root aphids once, some years back.....I traced that down to the wild grapes giving it to my wine grapes and then to my indoor opp.....There are NO MORE wild grapes within 200 meters of my farm.. I go out every year and kill off any new ones..

Now that's prevention.

 

[Renfro]

Standard hvac filters can catch a good % of mold spores.

Depends on the MERV rating. Unless it's a filter with a MERV rating of at least 7 or 8 it has little chance of catching mold spores. You need to catch 3 micron size particles. 1 micron is better as some mold spores can be that small.

 

[Dr. Who]

OK everybody. With that out of the way.. Time for a big statement...

The plants that had been in the room the longest.
Have had new and increasing outbreaks.
New plants into the room have had nothing... Problem is, they will not for long, with the others expressing advancing PM infestations.

The old plants may have less of that cuticle.
The new plants more.. These would be remaining the same in the new RH value vs the old as per the writer of the article's theory would indicate..The newer the plant was in the bloom area....The less to none it had.

I'm canning this till I can get this room harvested off and then return after a deep and complete sanitizing.

I want to run this in this entry room. It is the room that opens to the outside, by my garden. The garden has mama's squash and zucchini in it. Thy always get PM and I think it gets carried in and waits for happy conditions to take off..

This building is now back-up generated too..

So, am I saying this is bunk? NO, just needs the right start to test and test over the summer conditions I normally have.

In fact, I have shifted a whole nother spot to this. This spot has no trouble. I want to see if it remains and what the plants look like at 65-70% RH all through bloom.

45% does NOT hurt. I am intrigued by this guys theory on holding the cuticle as a primary defense......Just look at the response here, by those already doing a VPD chart RH value RH in their rooms. No infections...

We'll see how I do later....Till then. The other building is on the clock...

 

[Dr. Who]

Depends on the MERV rating. Unless it's a filter with a MERV rating of at least 7 or 8 it has little chance of catching mold spores. You need to catch 3 micron size particles. 1 micron is better as some mold spores can be that small.

I use the same lab rated filters from when I worked for BMS Pharama... All intake vent seams are sealed...

 

[ZeusBarks]

You don't know me very well......I've been growing cannabis for over 45 years now. I ran over 10 acres of commercial greenhouses in/after college to pay for college. I then was hired by a major US pharmaceutical company to run the whole Yew farm operation to make Taxol...Just to get a grip on how big that was. At one point we had 24,000,000 plants in various stages of growth. That area, covered square miles!

I grew up on a farm, and now in retirement. Run that farm and manage 4 more that created a now 5 farm organic co-op that supplies Produce, Dairy, Beef, Pork, Poultry and now moving the grain ops to Barley and Wheat for organic brewing for use in the two major brewing cities in our state. One has been given the national title of "Brew city USA". We are now expanding into more Hops area's for the same reason.

Outside air is never "toxic" to cannabis.....I grow some outside every year for my personal stash and Christmas gifts...... You make me laugh kid. My "out side air is BAD".....ROTHFLMAO!

I have one of the tightest environmentally controlled grow operations in the area.

All incoming air is HEPA filtered. The op is set up for gassing by CO2 generator(did you know they (mostly) are REALLY portable hot water makers for camping? - Yup, that's where the designs were stole from) I later choose NOT to gas.

Before I wrote this post.....Conditions were set for - Temps of 73 deg F at the therm. level. 45% RH and all strains dialed in on that. Night temp drops are normal... Everything is controlled by environmental controllers with fuzzy logic.

Here's last remaining pic of one 12x24 production room.
View attachment 4315885


That is a "support" the central AC system portable that is online for several months a year.

Each light now has a 400w Merc vapor under it, for added blue and UVB spectral bands. The inside the hood lamps are 1K HPS in Jupiter 6 hoods that deliver 20% more light. They are set at 6ft centers to overlap for one continuous lighting zone of high intensity light delivery - NO WEAK ZONES!

I have no real issues other then in the first building, and then in only one room. I made the dumb ass mistake of not sanitizing before I moved the operation in.... Chalk it up to being too damn excited to move in the new building....

Next thing is "jr".....That you carry spores into any facility that does not have a "blow off" area and shoe cleaning station.....Like a chick breeding poultry operation....They are everywhere. They only need the right conditions to actually start growing....

They got that in mine, this last spring when a storm caused a power failure in our area... Understand power failure now?

I was polite here.....

I won't be next time.

Oh yeah, I grow 4 different types of wine grapes for my own wine making.... I got root aphids once, some years back.....I traced that down to the wild grapes giving it to my wine grapes and then to my indoor opp.....There are NO MORE wild grapes within 200 meters of my farm.. I go out every year and kill off any new ones..

Now that's prevention.

So with all that filtration and extraction you clearly agree, sealed spaces mold.

P.S. feel free to be however nice or rude you are. You can run Phillip morrris future cannabis farm, crop dust your fields and bathe in vats of hash and it still won’t change the facts of mold growth.

Also, air can be very toxic to plants. That’s why growers monitor and manage temp/RH. Cannabis has a pretty narrow environmental band. Again, sounds like you know this since you quoted your own environmental condition

 

[Dr. Who]

Zeus, you are an odd fellow. You take a different path to room design.... I'm sure it works well. Just kinda different and not exactly well documented in many places (books shall we say) but interesting and annoying all at once.....

Simply moving air is a novel approach to preventing PM...... Once you supply the prime environmental conditions for cannabis........PM is generally a when and not an if......My opinion but it has proven true in the past..

I have to say that after running greenhouses for some years. I don't understand your ideal in greenhouse management..... In the summer and parts of the spring and fall. Yeah you use large fans (not to mention the open roof sections) to pull hot air out of the houses but turning it over in 3 min or less......Nah, I never dealt with that.....Then you have the winter. Heating systems keeping the ground warm and buildings warm. We sure didn't move air through for shit! We did move it around but, not turning it over with outdoors much at all...... Co2 generators did their part during those months. Adds RH too....


I suggest you pony up the several hundred dollars for a nice new Nelson's Greenhouse Guide and learn more about how a greenhouse really works.....Many seriously good things you could crossover to cannabis work.....

Later

 

[ZeusBarks]

Zeus, you are an odd fellow. You take a different path to room design.... I'm sure it works well. Just kinda different and not exactly well documented in many places (books shall we say) but interesting and annoying all at once.....

Simply moving air is a novel approach to preventing PM...... Once you supply the prime environmental conditions for cannabis........PM is generally a when and not an if......My opinion but it has proven true in the past..

I have to say that after running greenhouses for some years. I don't understand your ideal in greenhouse management..... In the summer and parts of the spring and fall. Yeah you use large fans (not to mention the open roof sections) to pull hot air out of the houses but turning it over in 3 min or less......Nah, I never dealt with that.....Then you have the winter. Heating systems keeping the ground warm and buildings warm. We sure didn't move air through for shit! We did move it around but, not turning it over with outdoors much at all...... Co2 generators did their part during those months. Adds RH too....


I suggest you pony up the several hundred dollars for a nice new Nelson's Greenhouse Guide and learn more about how a greenhouse really works.....Many seriously good things you could crossover to cannabis work.....

Later

You are completely ignoring the science of air movement. Traditional green house are not sealed they are open. Green house up heat and humidity for a crop. As you do that the hot air naturally rises and exchanges with colder air outside the green house. Growing indoor adds insulation and restricts are flow so yes you have to move the air. Green house are not sealed. Indoor grows have very little air exchange. You aren’t working in a green house for this grow but you should be, that is why you have to move air.