Has anyone defeated powdery mildew?

gthaenigma said:

I just read an article that tied pm issues to humidity. According to article they eliminated pm from their grow spaces by running 70% in veg and 60's for flower. I will try to find the article again and link it here.

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There's perhaps some truth to that, but there are members here who live in the desert and have had pm with 10% RH.

The article was in grow magazine and authored by todd mccormack. Talks about leaf vapor pressure deficit being the key to controlling it.

manfredo said:

There's perhaps some truth to that, but there are members here who live in the desert and have had pm with 10% RH.

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Low humidity is the problem according to the article. Says it affects stoma function by drying out the plants natural waxes leaving them vulnerable to infection. Very interesting article by a pioneer in the game.

gthaenigma said:

I just read an article that tied pm issues to humidity. According to article they eliminated pm from their grow spaces by running 70% in veg and 60's for flower. I will try to find the article again and link it here.

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PM absolutely LOVES it when you have swings back and forth from high to low humidity. Low humidity spreads spores and high humidity causes growth.

Renfro said:

PM absolutely LOVES it when you have swings back and forth from high to low humidity. Low humidity spreads spores and high humidity causes growth.

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I think that's how I initially got it...I'm in the north east and it's a constant struggle....Lower humidity in the winter, then it can spike to 90-100% in spring/summer.

But @curious2garden got pm and she lives in the desert with a fairly constant 10% RH....So as you said earlier, it's everywhere. I've been growing for 20 years though, and never had an issue until a year ago. I never even really knew what pm was. In fact that's the reason I joined this site, and a few people like curious2garden taught me the importance of an IPM program... and honestly I was at the end of my rope with it!

Every day I read here about people with bugs or pm, and they spend all kinds of money and time trying to get rid of the problem, when if they had a simple inexpensive IPM program from the start, would never have these issues.

I personally spent a lot of money before I bought the Regalia, replacing things, trying all these home remedies that nearly killed my plants, buying a ozone generator, cleaning, re-cleaning, etc... And 2 crops in a row that basically sucked, and I lost my 3 long running strains.

Loving my new IPM program, and wouldn't grow without one again. And it doesn't have to be Regalia / Venerate..If a sulfer burn works for you and you feel safe, make that part of your IPM program....but you should have something or sooner or later, you'll be sorry, IMHO.

I never had PM in 20+ years of growing in MO. We NEVER had low humidity. It wasn't until I moved to Colorado that I first encountered PM. It needs those RH% swings.

I totally agree on the need for preventative IPM, whatever works for you. Better to stop a problem before it starts than to try and clean it up afterwards.

So this is a really interesting thread. Lots of new stuff to learn for me, but it was well worth it.

To add to the UVC info:
So if anyone uses UVC lamps to disinfect the air at its intake, use without Ozone (O3) so 210-250nm (not below). Don't use them in tents XD or if, only swiftly manually or with Ozone, on a timer. For permanent sterilization of the air intake they need to be away from the inside because they gleam lightly (think of flower). Use aluminium as reflective, inside the pipes works very well + usersafe.

Regalia:
This stuff is superpotent versus PM. It's so effective it was worth of a great dissertation that had many Profs as assistance & financial support for extra studies. I've just "read it fast", and from what I could gather so far is:

- It works by activating the immunesystem of the plant, so it's somewhat similar to Chitosan. No clue if one should/could use them together.

- When a plant is infected it will create ROS (stuff that oxygenizes other molecues, and that is dangerous due to DNA damage & mutation) like H2O2 or NO which attacks all tissue but also, the infection. (After which the plant simply repairs its autodamage.... this way the immune system works in us, too BTW)

- Active known compound:

The Physcion can be given by foliar application but it must be directly after lights out, bc only when the stomatas are open it can find entrance to a leave (90mins window approx)

The clips says biocide/fungicide but it won't harm the microbes if one waters with it.

manfredo said:

Not true...I only used it twice in flower, at week 2 and week 4, and I'm in week 9 now. Next grow I'll probably skip it all together in flower, becaues I really don't like putting anything on flowers even if it is organic.

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Do you use it in your soil like recommended

Renfro said:

I never had PM in 20+ years of growing in MO. We NEVER had low humidity. It wasn't until I moved to Colorado that I first encountered PM. It needs those RH% swings.

I totally agree on the need for preventative IPM, whatever works for you. Better to stop a problem before it starts than to try and clean it up afterwards.

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so your saying I should keep my RH up in flower ??? I’m so confused rite now. Lol. Must be that fungaside I’m smoking. Lmao.

SickboyDilligaf said:

so your saying I should keep my RH up in flower ??? I’m so confused rite now. Lol. Must be that fungaside I’m smoking. Lmao.

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I am saying don't let it fluctuate much, avoid having times of really high and then really low RH% and back up again. For example, lets say we have our veg room and we like it up around 65 - 70% RH. Now say we live in an arid climate, and we must use a humidifier or swamp cooler to keep our room up at that high RH%. Say for some reason the humidifier quits and you don't notice it quick enough, the RH% drops into the low 30's. Thats the swings I am talking about. Try to stay within a 10% range, in your Goldilocks zone and don't go from wet to dry.

I never saw PM back in Missouri because it never got dry there, it was always humid except for winter but even then my grows were sealed / CO2 basement setups and because of stealth you couldn't have a hint of odor. So I always needed dehumidifiers, humidity was always trying to go above 50% and I had to fight to get it down to 45% in flower lol.

Powdery mildew just thrives on those large RH% swings. I believe that because it would stay above 50% that swinging from 50 - 70 wouldn't' be bad like a swing from 35 - 55. Does that make sense? Avoid being really dry ever, and if you must live with a really dry grow then NEVER let it get above 50%. If spores are present (difficult but not impossible to eliminate with expensive equipment running 24/7), conditions on the acidic side and you have those bad RH% swings then PM is ready to come out and play.

I am stoned af rn and hope that made sense lol.

If you wanna dump some coin and have state of the art whole room sanitation that is constant, able to address incoming bullshit on the fly, go here https://airrosshield.com/competitive-technologies

I installed three of these into my hvac system so it does the entire house including the flower room,they emit ZERO OZONE and kill pm at the source,one of my best investments ..it also kills germ/viruses.

The neat thing about the product I linked is it not only continuously sterilizes air but also surfaces and is safe for your plants if setup properly, they have sensors and all that jazz.

SickboyDilligaf said:

Do you use it in your soil like recommended

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I have, but I use 10G bags so root drenches would require a lot of product, so mainly I spray it on during veg, and I use at as a root dip when transplanting clones or seedlings, and dunk the entire plant in the solution for a few seconds.

I am still experimenting with it...my second batch since pm has been in the veg room for 16 weeks now...They are huge, and I have only sprayed them 4-5 times in that 16 weeks...with a few root drenches when they were in smaller pots and at transplant. I doubt I'll spray them past week 2 in flower this time, and maybe 1 root drench at like week 4 of flower...maybe.

And I've used the Venerate even less, as I have never had any bug problems, and just hoping to keep it that way.

And then silica I use all through veg and well into flower.

I’m moving to Louisiana. What kinda climate is there. I know it’s hot but how’s the Rh all year round. Anyone know. I do know that if I go outside at 3 o’clock in the morning to have a cigarette in the summer I come in dripping wet

SickboyDilligaf said:

I’m moving to Louisiana. What kinda climate is there. I know it’s hot but how’s the Rh all year round. Anyone know. I do know that if I go outside at 3 o’clock in the morning to have a cigarette in the summer I come in dripping wet

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Never been there, but I imagine it's similar to Florida...Humid all the time.

Cleaning my tent again. Black dots on floor. Only like 6 and tiny. Won’t come off for nutin!!! Is this mold ?? I’ve seen photos of PM with black dots in it

Nah...mold would wipe off of that surface I believe. It's the spores you can't see that you have to worry about....I cleaned and cleaned, and then used an ozone generator, and still the pm came back.

So I guess this won’t work lol Uv light