Getting rid of powder mildew from grow room

Discussion in 'Marijuana Plant Problems' started by Mr.budz, May 2, 2012.


    Mr.budz Member

    So I came across some powder mildew during my last grow and I know its very easily airborne transmitted. I'm wondering what the best way to make sure I cleanse my grow room so that there is no powder mildew resin hiding anywhere.

    cannofbliss Well-Known Member

    h2O2, and or light bleach solution, and lots of dry heat say 100 deg for about a day...

    90cody Active Member

    cannabis plant prooblems

    Powdery Mildew

    Mildew spores can be brought into the grow room through air ventilation into your grow room, your cloths, pets and be carried by animals outdoors. and land on the plant infecting other parts of the plant, buds, stems, stalks and leaves, also spores can land on indoor grow room walls, tubes, growing equipment, hoods, ballast&#8217;s, cords and etc. Spores can remain dormant until environment factors trigger it, like high humidity and cool temperatures, poor air circulation. Powdery mildew in vegetative growth is much easier to rid than in the later stages of flowering. Night time temperatures and moisture triggers spores to be released. The mildew eventually covers and coats the plant thus reducing the process of photosynthesis. If left untreated powdery mildew will infect all plants in your garden and coat your plants in flour like substance and cause leaves to &#8220;suffocate&#8221; Yellow and die off. If your plants are in flowering, depending how far into flowering, your buds will eventually become infected and will not be able to be used. Buds will have a stale moist smell and will be coated with a white powdery substance that can&#8217;t be removed no matter what you do. Very early detection in flowering plants that have powdery mildew is extremely important, the longer you wait in flowering the more impossible it gets to eradicate this, due to this, bud size gets bigger in flowering and having high humidity temperatures over 65% can trigger active spores to start, not only powdery mildew, but triggers other problems from it, like bud rot. Not only will you have lower yield, but you won&#8217;t have any buds, due to the fact mold has crippled your harvest.
    Strains vary in susceptibility to molds, just like other pathogens and nutrient requirements and care.

    Prevent and Control

    Symptoms of your plants having powdery mildew include: white blotches of furry stuff and white spots or splotches that you can wipe off, having humidity that is over 65%, also starts on darker areas of the plant and spreads to the top. Darker areas on your plant that do not get a lot of light will start to show this first, then when spores become active it spreads to everything. The longer you let it go the harder it will be to eradicate, late flowering plants that have this are extremely hard to get rid of, due to bud density thicker in late flowering plants, because of this the mildew attacks the buds which you can&#8217;t cure mildew once it affects the buds.(also known as Bud Rot)Plants that are stressed from environment factors, or fighting pest&#8217;s will be taken over more by this mold, due to the fact it&#8217;s already fighting problems. If you see your stressed plants getting it first, try to isolate the plant and bring down humidity, better air ventilation and or negative air pressure grow room. If you have mildew with your fans running, you will need to take them down and clean them as the fans can spread spores around the room. You will need to wash down everything in your indoor grow room, spores land on everything, so everything needs to be washed with mild hot water and bleach solution. Removing infected leaves from the grow room is critical, carefully removing them and trying to not knock spores into the air is a challenge. Applying a bag over infected leaves and tying it shut then removing it helps out with not knocking up spores in the air. Making sure you use h202 on stems that have open wounds from leaves that was removed. DO NOT water when lights are going to be going out, doing this keeps water on the plants soil and causes higher humidity levels, this goes for foliar feeding. Water plants when lights first come on or there is at least 5 hours left of lights on. You want to reduce the amount of humidity as possible if your levels of RH are high, you want to keep your humidity levels around 40 to 50%, and anything over 60% is going to trigger problems. Also keeping plants spaced apart allowing maximum air flow in between plants will help minimize plant to plant infection. Using a dehumidifier can greatly reduce humidity issues. Using a meter that tells your grow room conditions like temperature, RH and time can help combat your problems, by keeping track before and after you water can tell you how much if any your humidity can rise after changes made to the grow room. Sulphur Burner is another way to prevent and kill powdery mildew by vaporizing spores in the air. (Do not apply sulfur when air temperature is near or over 90°F) Controlling your mildew outdoors can be somewhat of a challenge, you can&#8217;t control outdoor temperatures, or environmental factors, Using Vapor Gard,Wilt Pruf sprayed over the leaves can prevent infection&#8217;s.
    You will need to treat your plants with various organic and chemical controls. This list will work for indoor and outdoor growers in killing and preventing Powdery Mildew. Outdoor growers can use Organics List below to help prevent Powdery Mildew of starting, even after it has started using anything below will help kill it off. (Note: When using chemical and or organic control methods, do not spray the buds, and for health and safety reasons, stay away from spraying around the buds if all possible.)

    Plant Shield
    Garden Disease Control
    Fungicide containing Lime, Sulphur

    JMS Stylet Oil
    Saf-T-Side Spray Oil
    Sunspray Ultra-Fine Spray Oil
    Neem Oil
    Neem 2
    Safer Garden Fungicide
    Concern Copper Soap Fungicide
    Guardian Angel
    Serenade Garden Disease Control OMRI
    Safer 3-in1 Garden Spray OMRI
    Sulfur Vaporizer
    Garden Sulphur
    Sulphur Burner
    Sodium Bicarbonate
    Mother Nature's Karanja Oil
    Concern Copper Soap Fungicide
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    [TD="class: td1, width: 20"][/TD]
    [TD="class: td2"][/TD]

    cannofbliss Well-Known Member

    good info^^^ but i think their grow is done with and they are just looking for cleaning it without cannabis in it... that is if i understood correctly... ;)

    90cody Active Member

    good call, took me a second read lol.

    in that case i agree with cannofbliss, i was wondering why would he want the grow room 100 degrees to get rid of powder mildew ha should have caught it then, just got done smoking.. my apologies :)

    i would use the light bleach solution mixed with plenty hydrogen peroxide mixed

    Bayou bud

    Bayou bud Active Member

    H2O2 is grand. Try to snip off and remove any leaf with mold, as long as it is less than 40% of the canopy. Adjust your humidity down 10-15% Check your night temps and RH as well. Throw in another oscillating fan, and when you do snip infected leaves put a cup or paper under each leaf to catch it when it falls. The powdery mildew will drop down off of the currently infected leaf and onto lower leaves and start wreaking havoc there next. Make sure fans are not blowing when snipping off these infected areas.

    I did this last night:

    -Turn off all venting and fans when you remove the mold or it'll blow everywhere.
    -Snip infected leafs with something to catch them with under them (your hand will have the powder stick to its oils, then rub off on the next leaf you touch), discard immediately
    -Spray down with H2O2
    -Reposition plants that were close to one another
    -Turn back on all venting and fans

    Mr.budz Member

    Ya, I am not growing eight now, I took everything out of my room, cleaning it with light hydrogen peroxide mix, I'm spraying down the with warm water, now I'm thinking of adding some peroxide to that water as well. Would you guys consider lighting a sulphur burner in there before I place any plants back in there.

    Im thinking...sulphur burner first then wash my room with a power washer with some peroxide in the water?

    Mr.budz Member

    Great info 90cody!!!

    panhead Moderator

    Once you get pm you are likely to have it over & over again,bleach & other cleaners only kill some of the spores,the only sure way to entirely rid a room of live pm spores is to seal the room & ozonate the room with mass dose ozone.

    Every grower should have atleast one ozone generator,rooms that are generaly damp & suceptable to pm can greatly reduce the risk in future grows by running an ozone generator full time,just be sure to research how to use one without killing the plants.

    I spray all my crops with copper soap the day before i put them into bud,this coats the pistils & calyxs that will end up inside the buds,spraying before bud growth explodes greatly reduces risk of blight or bud rott.

    Copper soap can also be used to kill off pm on buds in their final weeks,the product i use is BONIDE LIQUID COPPER SOAP & its safe to use on edibles.

    Optic1 Active Member

    Hey all, This post is a little old from the other month but since I am going again doing some plants here is something that worked well last fall when our rains hit.
    I did this both indoors and outdoors and it works very well. Humidity rocketed skywards last fall indoors also so I started getting mildew bad there too.

    Got Milk?

    The family recently bought a vineyard and I had to really bone up fast on some grape research.
    I stumbled on some research studies on the use of milk for powdery mildew.
    I have also passed the tips now to a few friends and there all very happy.
    First milk when it rots smells a little so I would not use whole milk indoors, that kinda stunk inside. Outdoors is fine.
    I have now found skim milk indoors works very well with no smell and just spray it on the plants. Mildew stops. Simple.

    I guess researchers found down in south america vineyards that the use of milk on grapes really upset the ph of powdery mildew and killed it.
    It has worked good so far and really is cheaper than any chemicals at 2 bucks a gallon. One gallon of milk gives you ten gallons of spray.
    For more info if interested just google using milk for powdery mildew control.
    You should find plenty of info from research studies on grapes and mildew.

    It has worked so well whole vineyards are now being crop dusted with milk.
    They are astounded at the results using something so simple.
    Use a 10% solution of skim milk added to water and I spray three times at first and you will be very pleased.
    You will find it works just as good as any chemical. Then mist here and there as needed.

    At least in your testing you do not need to spend a fortune just to try it. You probably have it in your kitchen.
    Plus one giant benefit is it is 100% safe and no worries.
    Best advice is to not go wild and maybe wipe down areas of over spray like your floor. Unless you feel walls and floor have tons of spores.
    I sprayed a whole room and problems just disappeared.
    Skim milk vs. whole milk both work the same, just the added fat in whole milk can result in an indoor smell.

    I wish ya good luck and big buds.

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