Powdery Mildew - Large scale Greenhouse

I am trying to be less of a dick lately but likesaid before, I agree with Frank.

Not to mention this is an inquiry from a sector of the industry that does everything in their power to malign us from head to toe as peddlers of poison while they themselves resort to irradiation to pass uninformed regulations they helped draft. A sector looking to wipe out our very existence. Who wins the first 14 year sentence designed to dissuade the competition?

Why would anyone treat them cordially?

People are running their sulfur pots during flowering, running 70% humidity with 5-10 % lower/higher during night periods vs day, even climate allows throughout the greenhouse allows higher humidity as you don't have larger temperature variations and dew point in certain spots with cold temperatures and higher humidity. I don't think you should run sulfur pots during flower and neither does health canada.

Botrytis has many control agents, just not in cannabis, smaller flowers dry out faster and hold less moisture, proper canopy management helps with microclimates as does your environmental controls, if you're have big swings and running pad fan etc then you're going to have to run much tighter and lower humidity. Dehumidifiers can work great yes but you don't need them if you have lower heating pipes and vents as most commercial greenhouses have. Drygair makes a great unit that people have used in greenhouses though and have a good reputation for reliability and function just be prepared to pay for them.

If you're a commercial grower, hire an advisor with long standing experience in a greenhouse and you will save a lot of headaches down the road, if you're in ontario I can tell you several that do this type of work for years in vegetable houses and have been branching into cannabis, if you don't have a crop advisor and you're in a commercial greenhouse, you'd better know your shit before you run amuck.

Just out of curiosity for all the experts in this thread and maybe some of their fanboys too. What general range would you suggest for vegging or flowering plants within a greenhouse? I'd suggest the %'s quoted here are not the OP's main issues unless those swings occur over a very short period of time - lack of light, poor air flow, piss poor VPD (obviously I know humidity is a piece to this equation), poor cultural practices and wrong strains are mostly to blame.... High humidity and temps and plants go gangbusters in a GH, adequate lighting a must.....

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The problem a lot of the new type of cannabis entrepreneurs have is they have no background in farming. They got high in college, maybe grew a few plants in their closet so they have 'experience' but that's not the same as growing 5000 plants in a greenhouse. Doesn't matter if you're clever, have a college degree, understand the basics of growing, you're going to lose a lot of money in the 3 or 4 years it takes you to figure out what the fuck you're doing.

There's a local greenhouse company that sells all the $1.50 veggie start 4 packs all over town. Their greenhouses aren't far from where I live and, I'm not sure what the relationship is, someone in my family knew someone in the greenhouse owner's family. I've been by there a few times, checked out their operations and looked over everything because of my interest in gardening. Everything's automated and dialed in. They've got thousands of pepper starts that require 80 degree temperatures and plenty of light ready to go April 1st. You know those people aren't running to the internet, 'Holy shit we've got PM what the fuck am I going to do!!!' And they aren't tossing around the kind of investment capital and profits that are common in the cannabis industry.

Doesn't matter if it's Alaska, what strains you've got, what conditions are required, if you start out with a bunch of PM clones, within a few days all that shit should be handled. Cannabis is generally a dry desert type plant, requires very low humidity. If you can't fix that in Veg when you should be testing the humidity getting it dialed in you're fucked. You shouldn't need to grow strains adapted to a tropical jungle because you're growing in a greenhouse. Deep Chunk's the most mold susceptible plant I've seen. You should be able to toss in 5000 Deep Chunks, dial the RH to high Afghan desert and watch 'em bloom.

This goes for a lot of indoor growers with much smaller grows. I've seen beautiful setups but I go in their room and the RH is 85% I'm dripping sweat after a couple minutes. In Veg especially the plants don't look bad so growers think it's alright but you're creating the perfect environment for disease and weakening your plants.

dank.frank said:

The OP of this thread deleted their account. As soon as they got the free information they were looking for, they left.

Exactly like I said from the very beginning.


dank.Frank

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I'd suggest it was more along these lines.......

1) How many LP's in Canada are ex-strawberry producers
2) How many of those are currently undergoing these issues, if there even exists more than one LP who are ex-strawberry folk in that region
3) How many of them are @ the size mentioned
4) How many of them LP's left (one) have consultants and how many total consultants are there

ding ding ding, not only was it likely fairly embarrassing it's quite likely with little effort one could know exactly who that was; that fella outed himself here, then realized it and jammed quickly IMO.... Not exactly good for business

Then again, maybe you're right and I totally wrong.... The difference is your certainty and arrogance along the way - MHO.... The information provided wasn't exactly groundbreaking either, just common for knowledgeable GH growers, it was mostly good advice though I agree....

Peace

chronic82 said:

No where on the label does it says it’s effective against botritys. I don’t think there is anything on the market that’s effective against botritys. Powdery mildew and budrot are 2 totally different problems

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https://www.tlhort.com/crop_protection_label_search/Actinovate_SP_-_Streptomyces_lydicus.pdf

It is supposed to be effective against botritys for cannabis, look it up.

I used it preventivly because I know lot of growers that got major budrot, but still got an outbreak.

But I was not controlling my environement proprely (Lack of experience and proper climate control.

Mikell said:

I am trying to be less of a dick lately but likesaid before, I agree with Frank.

Not to mention this is an inquiry from a sector of the industry that does everything in their power to malign us from head to toe as peddlers of poison while they themselves resort to irradiation to pass uninformed regulations they helped draft. A sector looking to wipe out our very existence. Who wins the first 14 year sentence designed to dissuade the competition?

Why would anyone treat them cordially?

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so true

Change your environment and the ph off your leaf. More air movement, lower humidity, higher temperatures and spray with potassium bicarbonate. Get rid of all signs off infection.

Heating a 30ft tall greenhouse in Canada is the problem.
You could use a climate screen to reduce your space to 8-10ft tall. That's 1/3 of the space to heat. Really the best investment for a greenhouse in cold climates is to ditch your standard black out fabric and use insulated curtain like they use for refrigerated warehouse zones.

therevverend said:

There's a local greenhouse company that sells all the $1.50 veggie start 4 packs all over town. Their greenhouses aren't far from where I live and, I'm not sure what the relationship is, someone in my family knew someone in the greenhouse owner's family. I've been by there a few times, checked out their operations and looked over everything because of my interest in gardening. Everything's automated and dialed in. They've got thousands of pepper starts that require 80 degree temperatures and plenty of light ready to go April 1st. You know those people aren't running to the internet, 'Holy shit we've got PM what the fuck am I going to do!!!' And they aren't tossing around the kind of investment capital and profits that are common in the cannabis industry.

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In the early 90’s I worked for a couple years as one of seven growers at a place that grew those spring bedding flowers and vegetables, all in those flats with either 32 or 72 cells in each.

I bring it up because this place was the opposite of high tech, flats were grown on wooden slats that were 3’x6’ frames, two inches above the ground. The owner believed his 3’x6’ frame tech at the time was innovative enough that he didn’t want me to take a picture of it when he saw me with a camera one day. To see the place flowering was a sight, had to get pics. The ground had 2-3 inches of chat, a waste product from lead mining.

At the time it was the largest bedding flat producer in the state, and all surrounding states, in the Midwest, outside of the Michigan area.

Between eighteen greenhouses they pumped out 15-17 million flats at 7$ a flat wholesale by the first week of June, and for the rest of the year they did repairs on buildings. They had a fleet of gooseneck trailers and trucks to deliver with.

There were not a lot of losses from disease, very minimal, biggest losses were from inexperienced “experts” who couldn’t water their sections properly. It was always a game of either pushing one group to be ready faster, or more often holding massive numbers through water stress by letting them go into full wilt and reviving them on a daily basis. A little stressful until you get the hang of it. The entire tomato house was run that way, even plants at eighteen inches were routinely let go till they looked like they wouldn’t recover, leaves would get watered and they were fine for a few more hours.

The bigger houses had 450,000 flats when full, I ran one of those and a 350, 000 one. When I started the place was entirely HAND watered.

Last year I was there we put in sprinklers which helped but was predictably uneven, more loss than with a competent hand water person.

I wasn’t in charge of pesticide apps, I assume they were not shy with their fungicide use but cannot confirm that. Grew everything from seed and had an efficient transplant system, mixed their own version of pro mix.

Just get yourself some peroxyacetic acid

dank.frank said:

300,000 sq ft grow consultant, has to come ask a bunch of hobby growers how to run their operation... (which is really 15,000 sq ft because cubic measurements are a different thing)

Perhaps if they hired experts in the first place, instead of trying to penny pinch and hire a basic labor force there wouldn't be powdery mildew issues.

Sorry. I have no pity on those who are in the game for purely capitalist objectives. You want answers? You should perhaps, HIRE A RISK MANAGEMENT CONSULTANT -oh wait, that's supposed to be you.

Seems to me this post is more about you saving face and your job.



dank.Frank

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G `day DF

I was just looking at this study from Holland .
As far as I know they know their shit when it comes to Green Houses .
But even they are learning on the job .

Ventilation has hardly any effect on spreading mildew spores in rose



The perfect rose is not a perfect rose, as long as powdery mildew stays on its head. Researcher Kirsten Leiss has been trying to get a grip on the fungus since March last year and has already been able to draw several sensational conclusions. With a resilient plant, much profit could be achieved, is the expectation.

Every week on the same day and at the same time, Kirsten Leiss and her researchers from Wageningen University & Research walk through the rose greenhouse to scoop powdery mildew. On one side is the now five-year-old Red Naomi breed. On the other hand, the variety Avalanche, which was only planted last spring. The researchers are looking for powdery mildew and if so, where it occurs in the greenhouse and how heavy the infestation is.For this they have developed a score, with which they have been mapping the entire greenhouse every week since March last year.

No spreading through ventilation
"It is interesting to see what has come out of this," says Leiss, WUR researcher at the business unit Greenhouse Horticulture in Bleiswijk. "Firstly, we see the worst damage on the middle paths. Secondly, young shoots suffer much less from the fungus than the older leaves and thirdly, there is much less mildew infection in the young Avalanche plant than in the older Red Naomi. It is noticeable that the mildew fireplaces remain in the same places during the time.They do not move. This means that ventilation has hardly any effect on the spread of mildew spores, a rather surprising conclusion. "

That she does not find any fireplaces at the young plants Avalanche is also surprising, she says. "I doubt that this is the breed. I hear from many growers that this variety is sensitive to this fungus. I think that it is the age of the crop. This effect can also be seen in the less sensitive young shoots of the Red Naomi compared to older leaf material. It is plausible to think that this has something to do with different leaf structures and components, "Leiss assumes.

Scouting versus climate sensors
The researcher was asked at the beginning of last year to do research on powdery mildew in roses. Colleagues were working on the project 'The perfect rose, the next level', commissioned by Kas as Energy Source and with energy saving as the starting point. How can 25% energy be saved in rose cultivation? By using LED lighting and OPAC heat exchangers, they were able to make progress in energy saving, but the researchers ran into another problem: the entire greenhouse was full of mildew. Spraying with fungicides took place every five days. "They asked me if I could do something about that fungus", says Leiss. "I have started mapping out the current situation in order to get targeted measures from here."

The data from the scouting is related to the data from climatic sensors, which measure the humidity and the temperature. These sensors measure within the crop at three heights: the leaves, the shoots and the buds. There appeared to be no differences in temperature and humidity between sites with and without mildew.

Fungicides do not kill traces
The life cycle of powdery mildew consists of a powdery layer, mycelium, visible on the leaves and traces that you can not see with the eye. In the literature she found that the fungal spores germinate at a humidity of 90% and at a temperature between 20 and 25 ° C, at night. The mycelium, on the other hand, benefits from an air humidity of 60 to 70% humidity and a temperature between 20 and 25 ° C, the situation during the day.

"Because the fungus often returns after spraying, my hypothesis is that fungicides cause the mycelium to die off, but that the spores remain and thus ensure that the fungus returns. This seems to be a problem especially for a crop like rose that stays in the greenhouse for several years. "

Fungicides only kill mycelium
To test their position, the researchers developed a test in which they collect mildew spores and identify and quantify them by molecular determinations. Mildew is a fungus that only grows on living plants and not on artificial media. That is why the researchers hung air samplers between the plants, which suck in air, so that the fungal spores fall on a filter.Through polymerase chain reaction - this is a way to multiply one or more parts from very small amounts of DNA until there is enough of it to analyze it - they could identify the traces and see if there were many or few of them. "We saw that there were many more traces in the leaves package than in the shoots. There was also much more in Red Naomi than in Avalanche. "

Then they took air samples before and after the spraying and it appeared that the sprays had no effect on the amount of spores. "This result therefore answers my hypothesis," says the researcher. "Fungicides only have a hold on the mycelium."

Reduce number of tracks
The logical next question was: What to do? "We have to reduce the number of tracks," says Leiss. "Cutting out the mildew's heads will significantly reduce the number of spores."

In addition, she has three methods in mind to kill traces in a sustainable way. The first is the use of UV-C. This has a disinfecting effect, but requires discipline from the grower, because this has to be done every day. In addition, the researcher wants to test plasma water and thirdly, she wants to start with the greenhouse temperature.

"In the literature, I found that if the greenhouse temperature is more than 30ºC for 1 to 2 hours per day, the number of spores dies significantly. The mildew scouting showed that after the very hot days of last summer with cabinet temperatures of more than 30 ° C, the mildew infestation decreased considerably. But in the context of energy saving and production; which grower wants this now? "

Yet the growers, with whom she regularly consults, thought along with her. They proposed that the temperature rise to 70 to 80 º C for a few seconds per day as a test by driving along the plants with a radiator and seeing what happens next. "So now we're going to try it out in a test setup."

Resilience
But because it involves substantial numbers of spores (up to more than 10,000 per mildew), you do not just manage to reduce spores. "Surviving traces must be able to germinate as little as possible", says Leiss.

She also wants to look more closely at the crop itself. "Nature already shows us a lot. For example, young, less susceptible rose petals look very different from older rose leaves. So the plant already shows us what we can do something with. I would also like to review the leaf morphology to investigate why less spores germinate here. Perhaps with this knowledge we can make plants less susceptible to mildew. "

She has already made a PPP application to compare secondary plant content substances and to relate them to mildew resistance. Meanwhile, she continues scouting. Every week on the same day and the same time. "The results so far are very interesting and will certainly remain so. At one point there will be a tipping point in Avalanche, where a fire will suddenly arise.That is very exciting for us as researchers. "

Resume
Kirsten Leiss, researcher in Bleiswijk, is researching mildew in rose and has already made a number of interesting discoveries. For example, fungicides only kill the mycelium and not the mildew spores. In addition, older leaf material appears to be more susceptible than young shoots. She thinks that a lot of profit can be gained if the plant itself can be made more resilient.

Text: Marjolein van Woerkom.
Picture: Studio GJ Vlekke.

dank.frank said:

300,000 sq ft grow consultant, has to come ask a bunch of hobby growers how to run their operation... (which is really 15,000 sq ft because cubic measurements are a different thing)

Perhaps if they hired experts in the first place, instead of trying to penny pinch and hire a basic labor force there wouldn't be powdery mildew issues.

Sorry. I have no pity on those who are in the game for purely capitalist objectives. You want answers? You should perhaps, HIRE A RISK MANAGEMENT CONSULTANT -oh wait, that's supposed to be you.

Seems to me this post is more about you saving face and your job.



dank.Frank

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G`day Frank

See above ...


Thanks for sharin

EB .

What is the highest day/night temperature that would be appropriate to grow quality flowers, if heating is the only option to reduce humidity in a greenhouse ?

for example; I need to reach 35c/95f to have rh below 40% during daytime, would having temps around 30c-35c at night to reach target rh really affect flower quality (terps, color, maturation)

I am wondering since indoor climate is very easy to control and never really had to deal with mold/rot before and always have cool temperature late in flower to help maturation/color...


(northern climate, very humid)

I'm sorry, this is fucking hilarious....

If heating is your only method with no venting possible you will not be having a great time over all, stretched out weaker plants will become more susceptible to diseases and pests and even worse collapsing from weight. You will need a place for the humid air to go, venting, exhaust fan, dehumidifiers are options. Keeping the climate even throughout is important as well, horizontal airflow fans above the crop blowing slowly and constantly help circulate the air and mix the layer which helps.

How in the fuck do you call yourself a grow consultant with 6 years experience, and cant control pm?

Wait for real trouble like russets or broad mites. Powdery mildew is child's play.

It fucking priceless to see these large ops that try to put us out of business not gave a harvest they can sell in any other form than distillate for 2 years. Until they bring in a black market goon like me.

Good luck man. Books are your friend. You remind me 9f the assuole who goes deer hunting sounding g like a rattling sporting goods store who cant even sight in his rifle...

Wendull C. said:

How in the fuck do you call yourself a grow consultant with 6 years experience, and cant control pm?

Wait for real trouble like russets or broad mites. Powdery mildew is child's play.

It fucking priceless to see these large ops that try to put us out of business not gave a harvest they can sell in any other form than distillate for 2 years. Until they bring in a black market goon like me.

Good luck man. Books are your friend. You remind me 9f the assuole who goes deer hunting sounding g like a rattling sporting goods store who cant even sight in his rifle...

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Little too late for literature at this point it seems.

Limeygreen said:

If heating is your only method with no venting possible you will not be having a great time over all, stretched out weaker plants will become more susceptible to diseases and pests and even worse collapsing from weight. You will need a place for the humid air to go, venting, exhaust fan, dehumidifiers are options. Keeping the climate even throughout is important as well, horizontal airflow fans above the crop blowing slowly and constantly help circulate the air and mix the layer which helps.

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I meant dehumidying by heating and opening the roof...
I have a bunch oft 4ft 20000cfm fans but isnt pointless if outside humidity is over 70% ?

Lots of very strong HAF...

My question was; how would cannabis react to high temperature at night(90f-35c) in terms of maturation and color at the end of flower , if heating and venting is the only way to keep botrytis away ?

G' day EB,

I think the point of your post has gone over the heads of some. Can't say I'm surprised, sadly.

Nice share.

Shmavis said:

G' day EB,

I think the point of your post has gone over the heads of some. Can't say I'm surprised, sadly.

Nice share.

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G `day Sh

Props to a friend who translated the article from Dutch to English .

I heard a saying as a kid ; you can lead a horse to water , but you can`t make him drink .

Thanks for sharin

EB .