Tales of the great battle of powdery mildew

[Drewsif]

Y’all are going at this wrong. Research actinovate. It’s active ingredient is an old antibiotic that humans used to take before amoxicillin came out. It will live in the surface of the leaf and eat any bacteria that lands on it. I’ve never seen it not work. Use double recommended dose with some coco wet. Spray weekly or just once

I read Dutch research where most fungal endophytes identified in Cannabis were Penicillium strains. Of course other studies show Aureobasidium, Alternaria, and Cochliobolus as the most prevalent fungal endophytes (with Pseudomonas, Pantoea, & Bacillus as most prevalent bacterial types). Obviously, each varietal and phenotype has a different demographic.

I guarantee someone has cultured various Cannabis endophytes with PM and published the results. I ain't gonna be published on ICMag.
Personally I simply reintroduce a varietals own trimmings into its own soil to boost whatever "bennies" work within varietal naturally.. For example hose unfamiliar with the reality of nature, my theory is backed by scientific experiment: https://www.sciencenews.org/article/plant-microbes-crops-food-endangered-species

Use the plants own microbes. Its that simple. People have been overthinking this shit for too long. How did mother nature get so far with milk and neem sprays?

 

[spazspaz]

Critic acid. Miracle. Insecticide and fungicide. Works great on pm. Can use at harvest. OMRI listed. Be careful not to make too strong of a mixture, especially on younger plants.

There are two brands I’m aware of in the US for the grow store crowd. The one I like comes in a .05% solution. Forget if the other is the same concentration. If you get a stronger product, you’re getting into herbicide territory—so, careful with your dilution!

One more warning: I hear that product sprayed with citric acid will test positive FOR fungus, since derived from yeast.

 

[spazspaz]

Also, one should be prepared to spray (under and over) at least once a week. Five to seven days seems to work fine for me, if I have no apparent powdery mildew. Maybe longer intervals are occasionally satisfactory.

Maybe don’t risk spraying clones as much—maybe don’t spray them at all (or wait until they’re rooted and go lightly. I don’t think I’ve ever seen mildew on a clone, though.) Probably best to spray moms before taking cuttings and avoid harshing out cuttings with sprays (other than a little water mist if necessary for humidificaction.)

I’ve already recommended citric acid. I also spray silica. In addition to saving money compared with adding it to my soil feeding solution, I’ve been told the acidity of the Si spray has similar effects as the citric acid spray. I wouldn’t rely on foliar Si alone as a pm treatment, but if you’re wondering why your plants are so mildew-free when you spray so infrequently with citric acid (or neem, or eagle 20, or buzzard 666) maybe it’s that...

No need to fear powdery mildew.

 

[digging]

Has anyone tried the AiroClean 420 machines.

https://www.airoclean420.com

They are suppose to be quite effective in getting rid of Powder Mildew …

 

[Hydro8]

PaulieWaulie Thanks for sharing your battle and experience with us. A couple of thoughts I had from looking at your pics.

Drainage- I looks like you pots are sitting on the saucers. Many times that will hold just enough moisture to keep cultures and spores reproducing. You might be able to raise the pots 1/2” from the saucers to keep air getting under them. Also good drain medium in the bottom of the pots will help.

Ideally, If you could make a trough for each row the air could get into it and dry the drainage out much quicker. Easier to clean and keep dry.

Airflow- The plants are close together and thick. If you could get nice rows to keep air moving in all directions. Platforms with legs would help the airflow under the plants.

Good Luck, thanks for sharing.

 

[MIhomegrown]

Also, one should be prepared to spray (under and over) at least once a week. Five to seven days seems to work fine for me, if I have no apparent powdery mildew. Maybe longer intervals are occasionally satisfactory.

Maybe don’t risk spraying clones as much—maybe don’t spray them at all (or wait until they’re rooted and go lightly. I don’t think I’ve ever seen mildew on a clone, though.) Probably best to spray moms before taking cuttings and avoid harshing out cuttings with sprays (other than a little water mist if necessary for humidificaction.)

I’ve already recommended citric acid. I also spray silica. In addition to saving money compared with adding it to my soil feeding solution, I’ve been told the acidity of the Si spray has similar effects as the citric acid spray. I wouldn’t rely on foliar Si alone as a pm treatment, but if you’re wondering why your plants are so mildew-free when you spray so infrequently with citric acid (or neem, or eagle 20, or buzzard 666) maybe it’s that...

No need to fear powdery mildew.

I used earth juice ph down which is citric acid. How does it prevent/kill if citric acid lowers ph. Silica raises ph on the plant surface when sprayed which doesn't allow pm to prosper.

 

[spazspaz]

I used earth juice ph down which is citric acid. How does it prevent/kill if citric acid lowers ph. Silica raises ph on the plant surface when sprayed which doesn't allow pm to prosper.

Hmmm. Perhaps needless to say, I do not have a grasp on the chemistry here. It does appear that I have been the recipient of Bro Science, in re: Purported pH of Si spray.

It seems that Si will have the opposite effect on pH than citric acid. This brings to mind ye olde baking soda treatment for PM.

Also, I’m reminded that I came across speculation that the yeast (listed in “other ingredients”) might be the secret to the brew I have referred to as ‘citric acid.’ There’s also water and potassium sorbate listed in “other,” but I always say ‘citric acid,’ since that’s what’s listed as the “active ingredient.” Mind you, this is a product intended for additional uses, not only PM.

There are quite a few things for me to investigate here. My severely limited knowledge and search engine plunking today are inadequate to answer your question.

Furthermore, many new questions arise—not least of which is, should I be concerned with pH level maintenance and changes on my plants’ surface? If I wanted to use silica and/or baking soda at various stages, for any reason, how might I best schedule things?

Thanks for pointing out my mistake. I’ll see what more I can learn about these things.

I will still enthusiastically recommend a product containing citric acid (and yeast, water, potassium sorbate) as a preventative and curative for PM. It’s also great as an insecticide.

Maybe it’s time to reacquaint myself with a pH pen, anyway.

I’m a little scared to ask, have you been spraying that pH down product for a while, or...? I don’t see anything on their website about a foliar treatment. Is there any mention on the label? Let me know if it’s my fault if everything is fried in the morning.

 

[MIhomegrown]

Hmmm. Perhaps needless to say, I do not have a grasp on the chemistry here. It does appear that I have been the recipient of Bro Science, in re: Purported pH of Si spray.

It seems that Si will have the opposite effect on pH than citric acid. This brings to mind ye olde baking soda treatment for PM.

Also, I’m reminded that I came across speculation that the yeast (listed in “other ingredients”) might be the secret to the brew I have referred to as ‘citric acid.’ There’s also water and potassium sorbate listed in “other,” but I always say ‘citric acid,’ since that’s what’s listed as the “active ingredient.” Mind you, this is a product intended for additional uses, not only PM.

There are quite a few things for me to investigate here. My severely limited knowledge and search engine plunking today are inadequate to answer your question.

Furthermore, many new questions arise—not least of which is, should I be concerned with pH level maintenance and changes on my plants’ surface? If I wanted to use silica and/or baking soda at various stages, for any reason, how might I best schedule things?

Thanks for pointing out my mistake. I’ll see what more I can learn about these things.

I will still enthusiastically recommend a product containing citric acid (and yeast, water, potassium sorbate) as a preventative and curative for PM. It’s also great as an insecticide.

Maybe it’s time to reacquaint myself with a pH pen, anyway.

I’m a little scared to ask, have you been spraying that pH down product for a while, or...? I don’t see anything on their website about a foliar treatment. Is there any mention on the label? Let me know if it’s my fault if everything is fried in the morning.

I never used the ph down as a foliar since I usually want to raise it. Silica is great and baking soda will raise ph as well but not recommended for flowering plants.

 

[big315smooth]

stopped at a friends yesterday he's been battling pm for years. his house from late 1800's poor insulation. warm when light are on and cold when off. doesnt really clean under plants poor air circulation. then other friend only gets patches of pm during late flower in winter months guessing temps jumping

 

[MIhomegrown]

stopped at a friends yesterday he's been battling pm for years. his house from late 1800's poor insulation. warm when light are on and cold when off. doesnt really clean under plants poor air circulation. then other friend only gets patches of pm during late flower in winter months guessing temps jumping

Yup temp swings will do it

 

[big315smooth]

makes sense the old house gets it bad the other just catches spots at end of flower depending strain

 

[ion]

temp/rh swings + lapse in health regimen = PM

ive went from pm on the buds to slight patches on leaves every fruiting/spore cycle in the span of 4 months.

soon will be PM'free'

PM has been a blessing in disguise fer me, quite seriously. if you dont freak out it's your friend. when/if you go off the rails with your op, it will let you know. after fighting it for 3mo it quietly whispered to me.....'your indoor environmental control is eeeeeverything. pay attention or tear it down"

i started paying better attention.

and for the vacuous, vapid growpro shop guy(who i hope is on here, but know he aint smart enough to be...) with 25 years experience and self-proclaimed title of king of cannabis(yea, more full of shit then the ghs guy) who stated PM is systemic, you'll never get rid of it, trash everything you new grower........you can find an OFF to fornicate with, then go boil an egg.

 

[p0opstlnksal0t]

who stated PM is systemic, you'll never get rid of it, trash everything you new grower........you can find an OFF to fornicate with, then go boil an egg.

its out of ignorance. its most certainly not systemic and can almost always be cured by getting that climate in check. PM is fucking everywhere and no one is growing in a 100% sterile lab.

 

[siftedunity]

theres a reason why most pm sprays are systemic. not necessarily that pm is systemic, but if you read its life cycle it does appear to be within the leaves to some degree. that's from the information ive read anyway.. but still reading..

 

[mean mr.mustard]

Wettable sulphur...?

 

[Bwanabud]

Could someone please enlighten me as to the best environmental temp/humidity range, to prevent PM ?


I have tons of fans and air flow, lows in the 72-74F...highs 82-84F range,,,,humidity range about 39-45% light & dark period.


I just just it last grow, first time in 10 years, now spraying Green Cure every 5 days and it's still showing new spots on leaves...4 weeks into flower.

 

[zachrockbadenof]

Could someone please enlighten me as to the best environmental temp/humidity range, to prevent PM ?
I have tons of fans and air flow, lows in the 72-74F...highs 82-84F range,,,,humidity range about 39-45% light & dark period.
I just just it last grow, first time in 10 years, now spraying Green Cure every 5 days and it's still showing new spots on leaves...4 weeks into flower.

i never had pm till i took some plants outside late last summer , and started to bring them in a shed at nite to try and prevent bud rot . i had a fan blowing air around them. had no bud rot, but PM instead. i took clipping of the plants for a winter grow in a tent, and even after dipping them in greencure, and spraying them with milk, i still now have PM in my tent- i'm 3odd weeks from harvest and have hit em a couple times already with greencure, the PM shit still comes back..

at the end of the harvest i will clean the buds with hyd peroxide , lemon juice/etc which removes the PM... and this summer will 'nuke' the tent area ... but that shit is in the air - spores are everywhere... not sure if i will ever able to rid the area...

 

[Lyfespan]

npk raws omina will fortify plants so they cant grow PM, your welcome

 

[Sam_Skunkman]

PM can be eliminated one way for sure, Do not plant or grow any variety that gets PM, that may not be something you are willing to do but it works.
As soon as you see any PM on any variety, quit using that variety.

Different varieties have major differences in susceptibility, WLD like Afghan are the worst, hybrids with WLD in them are also bad. A few years ago I had 1000 seedlings imported from Afghanistan growing in my greenhouse, almost all got PM, while a few OHaze clones a NLD variety from near the Equator, that were also in the greenhouse and completely surrounded by the Afghans did not have or get PM, coming from a hot humid country they have a high resistance to Molds and PM unlike the Afghan WLD varieties with almost no resistance.
People that have PM problems need to only grow varieties that do not get PM, and the problem will be gone.
And not using PM prone varieties will encourage breeders to not use PM susceptible varieties in the first place to breed with.

Someone needs to start a list of PM susceptible Varieties and Landraces and Hybrids along with a list of PM resistant Varieties be they Landraces or Hybrids. There are enough growers on IC that if all their experiences were in a Cannabis PM susceptible list it would really help the newer growers without the experience to avoid WLD varieties that almost always have PM susceptibility where it is a problem. Breeders are to blame for using and making varieties that do have PM problems, I destroyed any I found, and I found a lot growing mostly imported seeds over the years looking for keepers.
-SamS

 

[HorseBadoritiz]

I took in a clone I really wanted back, and never even thought it might have pm... fuck me!


For two years I tried a lot of concoctions: milk, aminos, aminos and Ca, SNS90, compost teas, bicarb, potassium bicarb....and the list went on and on, and even on-er!


I grow in a crawlspace under the house, couldn't sulfur bomb cos of all the mechanicals, and a lifetime of construction tools and other really sensitive and important junk!.


Green Cure was the last spray. It controlled, but didn't eliminate, then rinsing the buds in H2O2 cleaned things up at harvest.


Last straw was getting some bud rot from spraying, okay overspraying, and losing a few ounces. Not much to most, but a lot to me and those I help out.


I'd read about UV-c, and was too chickenshit to give it a go, plus I'm a cheap bastige. Anyway, I found a ClearLight Pro for a good price, about an oz!


There's a learning curve, and it's potentially dangerous to both me and the plants, but after 4 months, I am finally seeing no more pm... at all, nada.


RH regulation, lower N in feeds, major air circulation, temp control in conjunction with all the other shit I tried did nothing but marginally control it. Granted, I may not have tried everything in the right ways, or even all the right things, but I tried... anyway cleanlight has meant no more foliars, none, and no more rot, none... at least for me, and I'm what's important, right, lol!