White Powdery Mildew

@bob31 @Donaldj @Covertgrower @Screwauger @dbrn32
Its been a little humid in my fridge the last two days with it being very cold and using a propane heater. I jist noticed a couple of small white circular patterns on leaves. I know its WPM. I went ahead and quarantined the leaves (snipped and tied in plastic bags). Im afraid i may have disturbed some spores. Is there anything you can recommend to treat the rest of plant before any more happens? Would a foilar spray be ideal?

50/50 milk water mist but since this grow is a fridge I am currious why you need heat? I would be circulating exhaust back into it to add warmth.

@Donaldj sorry i wasnt very clear; the fridge isnt functioning, im just using the shell, so it doesn’t keep any cold. The propane heater in is the shed tjat the fridge is in. When lights go out at 12am it gets to like 30 in shed, so i turn on proprane heater. Lights come back on at 12pm, but sometimes i am at work and am not able to get home to turn heater off, so sometimes it gets too warm in shed for about an hour or two! I have another tent coming, but i wanted to solve this so as not to cross contaminate!


@Donaldj that will be ok? i forgot to mention i am 4 weeks into flowering

I am aware and have been tracking the thread so what I am saying is based on fact that a fridge is well insulated and that propane heater creates high levels of co2 which raises RH drastically. You should be able to put fans and exhaust on timer so during dark the fridge gradually cools when lights go offand warms again when lights come on. If I unplug my fridge it stays cold for hours insulation works both ways holds warmth or cold

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It’s 30f out rightnow and I know if power were to go off my shed would hold enough heat for my ladies for 12-14hrs before I would start to think about adding a heater :wink: If you are in the must add heat thinking then use a dry heat source space heater, propane and fuel heaters create greenhouse gases co2 carbon monoxide water steam etc… most who use co2 generators have to dehumidify


@Donaldj the fans stay on all the time

that is my point by turning it off during dark cycle heat would stay in fridge for hours :slight_smile:


lets look at this from different angle a plant during flower wants a 10-15f swing dark to light and exhaust and fans are designed and used for 1 reason to remove heat. So if I didn’t remove heat it would climb but if I take away source of heat what does the fan do? it continues to cool when it is no longer needing to in our case I say our because I grow in a cold climate with no heater we don’t want it to cool. We want to store heat for future use fortunately our pots and reservoirs do that quite well releasing it slowly in the dark as long as we don’t let it escape too fast or take it away I insulated my shed but a fridge is an insulated box too :wink: if you were using a tent that’s another story

I second @Donaldj suggestion. Just turn off the fans at night to keep warmth in. @VelcroThumb the other thought is spray everything with hydrogen peroxide. A lot of people have used milk though, I’m just not familiar with it.

Bad… it will burn your leaves if using peroxide it needs to be cut almost to a non effective concentration apple cider vinegar likewise milk has protein and coats leaves in a film which mildew can’t grow in


Thanks @Donaldj


@Donaldj isnt one of the main things to not turn on exhaust fans and intake fans? But i get how to prevent the mildew… my question was moreso regarding fixing the present situation. My fridge also gets down to lower than 40 degrees if there is no other heat source. Running LED in fridge and it puts off np heat

@Donaldj as for milk, does one work better than another? 1% vs 2% vs skim vs whole?

Soil or hydro? a heating mat under plants adds warmth. As for air movement helping to prevent mildew yes and no mildew doesn’t like cold but a fan can spread it too. Ok lets rethink exhaust is too fast if you can’t keep heat or raise it enough even with lights on and air movement doesn’t always mean exhaust :wink: a closed room with a fan running has air movement exhaust is to remove exchange air and cool but whole grow rooms are built with no exhaust or intake. So perhaps we should be looking at the exhaust itself being an issue

@Donaldj exhaust fan cant get any slower. Growing in soil in fabric pot. Heat is no issue when lights are on, except for the 2 days that it got too warm once lights turn on and heater was still on. So everything being equal from here on out, i just need to take care of the mildew i have (which is minimal now). New tent coming today so it wont be an issue after this!

Very hard to explain a concept which is in my mind and seems easy to me some days? I actually recycle air in my space I don’t exhaust it unless temps are too high my exhaust vents into open space pre-warming cooler fresh air but I built a grow box last winter which just used exhaust fan for everything including air movement basically by circulating exhaust directly back into space but was also -14f- -20f

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@Donaldj does type or percent of milk matter?

not realy it’s the film milk leaves that kills and prevents though higher % is fat which could potentially clog stomata so I would go with 1% and when you get these ladies through scrub everything with bleach

@Donaldj awesome, gotcha!!! Is there prime time to do this; right before lights out or while lights are out