Powdery Mildew

Discussion in 'Growing Marijuana Outdoors' started by BrianR32GTR, Aug 8, 2019.

  1. I searched and tried reading some old posts but couldn't find the beat definitive answer.

    It's been really humid these last couple days and I've noticed on some fan leaves a small amount of PM growing.

    What's the best way to nip this in the butt before it gets out or control. The plants are outside and in a spot that receives airflow but unfortunately it's just been humid and no wind.

    Any products that will eradicate the problem?


    Sent from my SM-N950W using Grasscity Forum mobile app
  2. Green Cure once a week will control it. Found at most hydroponic stores
    Baking soda can be used in a pinch. 1 tablespoon per gallon of water.

    Cure = potassium bicarbonate
    Baking soda = Sodium bicarbonate.

    • Informative Informative x 1
  3. I might use the baking soda just to hit it before I can get green cure. Would you advise spraying the whole plant or only where its visible?


    Sent from my SM-N950W using Grasscity Forum mobile app
  4. I might have some as well in one plant. I don't have baking soda at hand, but bicarbonate of soda (for cleaning and bath bombs), would that do the trick?
  5. It's the same thing.

    Sent from my [illustrious_imagination] using Grasscity Forum mobile app
  6. Spray the entire plant. While it is a systemic infestation and the whole plant has it all we can do is control what shows on the surface. It's on the entire plant and will start to show everywhere eventually.

    If your new to outside growing consider finding BT while your shopping. It's for caterpillar control and them little bastards are the biggest threat to an outside plant.
    Also known as Bud Worms they can really screw up your plant and you may not find them till harvest and by then it's way to late.
    Bacillus Thuringiensis
    Once a week every week in flower right up to harvest. The primary enemy is the Tobacco moth and BT is only effective on their larva. The cattie has to eat some treated leaf then it forms crystals in their digestive tract and they die. Very safe it's organic grow rated and harmless to fish, birds and humans.
    Local garden center should have it for hornworm control on tomatoes.

    I run a bug zapper nearby to help limit the moths that are the trouble in the first place. I lost my first big outside grow to caterpillars as I didn't know about them. Tossed out 5 pounds of what looks beautiful till I hung it up. Dozens crawled out the first day. Hundreds the 3rd day. By the end of the week thousands were hanging from silk and every dot of caterpillar crap had a big blob of mold around it. Total loss.

    • Like Like x 1
    • Like Like x 1
  7. unfortunately pm is impossible to get rid of. when i noticed plants catching it I tried everything. I even took out the big guns for a last shot. I tented plants and fogged them in stages of sulpher, in a burner.

    I learned to keep healthier plants. I went full organic, and added things like silicate. along with health of plants the silicate toughens up all plant fibre. think of it being another big block in the wall to guard off pathogens bugs, etc.

    as another measure especially during damp conditions (i try to maintain a routine) foliar spray with a mild worm casting tea. not only is it good for your plants diet. the friendly bacteria sets up and even those give things like bad bacterias. think if them as microscopic little armies fighting another level of defense of your plants.

    the best defense in any army is multi layered.

    good luck with the pm nasties. you may be able to control it some what but never rid it. In all my time of growing Ive had to throw nugs in there prime away cuz I wont chance smoking it.
  8. P.m. is not impossible to get rid of, just difficult. All your treatments you described using are surface level treatments. Since PM is a systemic fungus, you need a systemic fungicide. You can only use sulphur burners and green cure and the like for prevention because it changes the ph of the leaf and doesn't allow new spores to take hold from the outside -> in, you want something that works from the inside-> out. There's right ways (organocide plant dr) and wrong ways (eagle 20) to go about doing it. Most systemics I would never be putting on products for combustion and inhalation.
  9. if no visible evidence of pm shows after treatment you can bet it will pop up again later.

    preventative is the best defence starting from day one.
  10. Sadly plant doctor also isn't available in Canada... not that I can find however.. I've o my had issues with PM once and it was a nightmare when I had it during flower... had to remove some good buds due to eventual bud rot.

    Sent from my SM-N950W using Grasscity Forum mobile app
    • Like Like x 1
  11. Do you have any hydro stores near you? I'm in Ontario and picked up potassium bicarbonate which is the main ingredient in green cure. H202 is supposed to help as well but look up dosing as I can't remember off hand.

    *Edit* If it isn't flowering yet pick up this
  12. sns-244c

    Sierra Natural Science
    go to website
    pay for shipping they will send samples

    Sent from my iPhone using Grasscity Forum
  13. Hey there. I'm having PM problems. I live on Cape Cod, so the shit is literally everywhere here. All 4 of my plants have it to varying degrees. How do I destroy this shit? The plants are still about 2 weeks out from harvest... I have tried baking soda solution and it didn't do shit.
  14. Green Cure...
    or neem oil.
  15. I'll look into greencure. Is it safe to use on buds very close to harvest? I aint spraying neem oil on mature buds. No way. I'll use it in Veg, but it aint going on buds.
  16. I do not know.

Share This Page