1st time with powdery mildew

Leeboy · Dec 5, 2025

In over 20 years I’ve never had powdery mildew on my plants . Had to throw out 7-8 when I saw a sign. My humidity never goes past 40% at most . I have a AC infinity exhaust 24/7 and hurricane fan always on in the 4x4 but somehow I saw it. It was mostly on some sugar leaves ( buds were extra sticky this run) So I tossed everything but one plant that’s about 2 weeks into flower which I haven’t seen anything on it .
Wondering if I should pull the plant , wipe everything down with bleach in the tent ? Run a ozenator ? Crank up the heat to kill it ? What should I spray my plant down with to prevent . What’s the latest and greatest ? Thanks

Ninjadogma · Dec 5, 2025

Leeboy said:
In over 20 years I’ve never had powdery mildew on my plants . Had to throw out 7-8 when I saw a sign. My humidity never goes past 40% at most . I have a AC infinity exhaust 24/7 and hurricane fan always on in the 4x4 but somehow I saw it. It was mostly on some sugar leaves ( buds were extra sticky this run) So I tossed everything but one plant that’s about 2 weeks into flower which I haven’t seen anything on it .
Wondering if I should pull the plant , wipe everything down with bleach in the tent ? Run a ozenator ? Crank up the heat to kill it ? What should I spray my plant down with to prevent . What’s the latest and greatest ? Thanks

Controlling environment is first line of prevention defense. After that...

Good HEPA filters in your air system to reduce spore count.

Add UV-B lights to kill spores.

Spot treat with a potassium bicarbonate spray like Kaligreen if you find it, can be used all the way to harvest.

When you're done with the grow, sterilize the tent so lingering spores don't come back to haunt you.

Been getting hit with WPM on my tomatoes and green beans lately but thankfully not my weed. I've just been hitting it with Neem, too bad it doesn't work well around buds.

PlumberSoCal2 · Dec 5, 2025

I watched a Scotty Real video on indoor IPM on YouTube. You might wanna give it a watch

imgrowing · Dec 5, 2025

milk and water mixture kills it with 1 shot. been there done that

Leeboy · Dec 5, 2025

imgrowing said:
milk and water mixture kills it with 1 shot. been there done that

What's the ratio you used ? I was either going to try peroxide and water tonight or I will try the milk. Only thing is girlfriend buys organic skim.

Smokey0418 · Dec 6, 2025

Leeboy said:
In over 20 years I’ve never had powdery mildew on my plants . Had to throw out 7-8 when I saw a sign. My humidity never goes past 40% at most . I have a AC infinity exhaust 24/7 and hurricane fan always on in the 4x4 but somehow I saw it. It was mostly on some sugar leaves ( buds were extra sticky this run) So I tossed everything but one plant that’s about 2 weeks into flower which I haven’t seen anything on it .
Wondering if I should pull the plant , wipe everything down with bleach in the tent ? Run a ozenator ? Crank up the heat to kill it ? What should I spray my plant down with to prevent . What’s the latest and greatest ? Thanks

Have had a few bouts with mildew.

Easiest resolve it to spray a dose of wettable sulphur “prior to flower” .

It’s like the info commercial , “ set it and forget it”
This would be “ spray it and forget it “

Good luck with any other resolve , once it’s got control you’re pucked.

imgrowing · Dec 7, 2025

Leeboy said:
What's the ratio you used ? I was either going to try peroxide and water tonight or I will try the milk. Only thing is girlfriend buys organic skim.

sorry for late reply.
not sure of the ratio but it's online

GNick55 · Dec 7, 2025

is it grey or white coloured,. i’m with @Smokey0418 that shit adapts so fast it’s impossible to get rid of, some seem to get lucky sometimes but that’s just luck,. i’ve beaten it before though the last few times it won and i just killed the plants,. i usually get it 3-4 weeks into flower,..
if i get it again in the future my next attempt will be with peroxide, baking soda and lemon juice,..
potassium bicarbonate with a wetting agent is probably your best choice,..

amneziaHaze · Dec 8, 2025

Thats why i do epson salt spray before flower helps the plant and protects it later

pnwbluntman · Dec 8, 2025

In California we would make a 1.5% peroxide mix with distilled water, and foilar spray to help prevent and sometimes you find one bud with it on it you bag and chop that limb, so no spore transfer while removing and spray surrounding buds with the spray, it is usually from pests bringing spores onto the plant, or someone brought it into your grow area on clothing. (Most problems I have had is from other growers bringing their problems unintentionally over, that's why I am the only one in mine now, other than one other buddy of mine that just takes a peak but doesn't go in) It's best to clean everything with bleach, and be sure to thoroughly clean your fan, clean or replace filter, and the ducting. The room the plant is in will need to be cleaned also. Pm is a bitch and so are spider mites. Once it's inside your grow inside you have to either stop and clean, or you will get it onto any survivors left in the grow area.

amneziaHaze · Dec 8, 2025

pnwbluntman said:
In California we would make a 1.5% peroxide mix with distilled water, and foilar spray to help prevent and sometimes you find one bud with it on it you bag and chop that limb, so no spore transfer while removing and spray surrounding buds with the spray, it is usually from pests bringing spores onto the plant, or someone brought it into your grow area on clothing. (Most problems I have had is from other growers bringing their problems unintentionally over, that's why I am the only one in mine now, other than one other buddy of mine that just takes a peak but doesn't go in) It's best to clean everything with bleach, and be sure to thoroughly clean your fan, clean or replace filter, and the ducting. The room the plant is in will need to be cleaned also. Pm is a bitch and so are spider mites. Once it's inside your grow inside you have to either stop and clean, or you will get it onto any survivors left in the grow area.

That amount % doesnt do anythibg to mold

Leeboy · Dec 30, 2025

Just an update . I took out all the plants , and ran an ozenator inside the tent . Put some clones I had inside my house ( grow tent is in the garage) . I sprayed the plants heavy with peroxide and water 1:4 part with water. Today , I looked at a couple leafs on one plant and noticed some white . After the pics I tried rubbing the white off and it’s like it’s embed in there kinda. The fluffs come off but the white ring still is there. So , I’m 3 weeks or so in flower . I’m wondering if I can spray again ? Peroxide again ? A milk mix? I’d like to spray the little mini buds and everything else if possible just to be safe. Or toss it all again including the tent . Thoughts ?

Leeboy · Dec 30, 2025

Here’s a pic after I washed it with a cloth . My humidity is between 30% and 35% maybe that’s too low ?

GNick55 · Dec 30, 2025

let’s see the whole plant,.
some forms of the wpm are impossible to get rid of,.. you’ll be fighting it till finish and harvest will be sub par at best,.
no reason to throw tent away

LoveGrowingIt · Dec 30, 2025

I've had good results treating WPM by spraying the leaves with a water and milk solution. I used a mixture ratio I found on the web: Combine 1 part milk (skim, 1%, 2%, or whole) with 2 to 4 parts water in a spray bottle or garden sprayer.

Grownsince95 · Dec 30, 2025

PM thrives in extremes. It actually prefers warm and dry during the day and cool and damp at night. If you can reduce your environmental swings you will be halfway there. 78° air with 45% humidity cooled to 68° now has 65% rh. Cool it to 75 and you're still below 50%. Boosting lights off temp to be at least as warm or warmer than the day will help a lot but I know most growers are uncomfortable with that. Try to at least get the day/night temp difference to 5° or less and you will see an improvement in prevention.

Many of us tent growers experience a big jump in humidity when the lights go off and it's exactly the kind of seesaw that PM loves to take advantage of.

Greenadian · Jan 2, 2026

I have battled the WPM twice in the last few months. Its a pain in the ass. I have removed all grow cabinets, grow chamber amd tent!!
One small room, better temperature regulation, increased the humidity during lights on (was at 38%) now at 53%, increased the exhaust fan power, added another small oscillating fan. Hopefully it does not raise ots ugly head again!!!
I feel for ya bro!!! Pain in the ass

Hossgrows · Jan 2, 2026

LoveGrowingIt said:
I've had good results treating WPM by spraying the leaves with a water and milk solution. I used a mixture ratio I found on the web: Combine 1 part milk (skim, 1%, 2%, or whole) with 2 to 4 parts water in a spray bottle or garden sprayer.

Same here. I didn't chance it, and used it straight. It was a couple weeks before harvest when I noticed it on some of the leaves, and had found a bit of bud rot, too.

Soaked the whole plant, so it stunk for a few day's, but worked wonders. Rain and a spray before harvest cleaned it all off, but it held on thru the heavy evening dews, till then .

I used whole milk, only the best for my kids.

dreamnfox · Jan 3, 2026

sulfur is really the best thing for PM, if you are in flower, then its not really an option, unless its the first couple weeks, in veg you can use a burner or just use the powdered sulfur and dust every surface

Hossgrows · Jan 4, 2026

dreamnfox said:
sulfur is really the best thing for PM, if you are in flower, then its not really an option, unless its the first couple weeks, in veg you can use a burner or just use the powdered sulfur and dust every surface

Nice to know. How much in cost, compared to a gallon of milk, though.
Aren't both just changing the pH.? Or is there other benefits to the sulfur. Milk gives some quick calcium....so they say. But what about what it might do to the soil is my concern. I grow in ground, and don't know what kind of residual affect it may have, or not. There's always soil testing and lime, I guess.

1st time with powdery mildew

1st time with powdery mildew

Leeboy

Ninjadogma

PlumberSoCal2

imgrowing

Leeboy

Smokey0418

imgrowing

GNick55

amneziaHaze

pnwbluntman

amneziaHaze

Leeboy

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Leeboy

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GNick55

LoveGrowingIt

Grownsince95

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Greenadian

Hossgrows

dreamnfox

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1st time with powdery mildew

1st time with powdery mildew

Leeboy

Ninjadogma

PlumberSoCal2

imgrowing

Leeboy

Smokey0418

imgrowing

GNick55

amneziaHaze

pnwbluntman

amneziaHaze

Leeboy

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Leeboy

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GNick55

LoveGrowingIt

Grownsince95

🤘😆👍

Greenadian

Hossgrows

dreamnfox

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