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How To Use Uvc Light To Treat Powdery Mildew- Please Help!

Discussion in 'Hydroponics' started by Greengrower8, Aug 12, 2018.

  1. Plants are 3 weeks into flower and I’m about done trying to treat my PM problem by spraying different liquids all over everything and it’s not working anyways.

    I know UVC light can be used to kill PM, but at what concentration? Will a 3 watt handheld UVC light work to get rid of this? How should I be exposing my plants to this sort of light in order to kill the PM without damaging the plants?

    Please help! Thanks!!
  2. Here's an easy way to beat powdery mildew - Don't let your night temps get below 70F. It can't germinate if night temps aren't low. Treat an existing infection with a horticultural oil like JMS Stylet Oil.
  3. Temps are always between 73 and 79. I have doused them in straight 3% hydrogen peroxide and with Armor Si (silicon). (Separate treatments) Added Armor Si to res. Spot treated with each. It just keeps returning. I will look into this oil. Is it safe for flowers? Most of the stuff to treat it cannot be sprayed on flowers. Thanks!
    45North likes this.
  4. CrimsonEcho

    CrimsonEcho Premium Member Supporter

    Use potassium bicarbonate, it works by shifting the ph. It will not completely cure it, neither will the oil and i don’t think it is suitable to use on flowers you are going to smoke, takes time for oil to breakdown.
    There is a milk cure but, if i am not mistaken, not after 2nd week of blooming.
    If you have decaying plant matter around your grow area get rid of it, don’t get the leaves wet, drop rh to 40%ish.
    Get a better air circulation around the plant ie. More fans.
    Give more info please. Rh, lights, medium etc.
    Aqua Man likes this.
  5. Plants are in dwc setup, fed half strength GH trio, treated with Hydrogaurd and armor Si. Have 2 inline fans cooling 5 600w hps’. There are also 3 box fans and 1 oscillating fan creating air circulation.
    Rh stays around 65% and doesn’t fluctuate much. This is according to my digital hydrostat which are notoriously inaccurate. I can’t get it much lower. I have used a dehumidifier and it only helps a few % and it creates heat on top of it. I have trimmed the plants down considerably to create more air flow.
    Again, these plants are well into flower and pretty much nothing should be sprayed on them from what I’ve read.

    This is why I was looking into using UVC light.

    I would love to make an environment change to help it, but I dunno what else I can do.
  6. Do not use UVC light on your plants it WILL KILL THEM. Its nasty shit and would only use to steralize after harvest to kill any remaining spores before starting another grow
    SwampHerb and CrimsonEcho like this.
  7. UVC light will NOT kill the plants themselves as long as the exposure is correct and that is my question. UVC light has been proven to control PM without harming plants, but exposure power and time are crucial.
    Jack og, CrimsonEcho and Aqua Man like this.
  8. Let me know how that works for you ok. I stand by my statement
    SwampHerb and CrimsonEcho like this.
  9. Aqua Man likes this.
  10. CrimsonEcho

    CrimsonEcho Premium Member Supporter

    Yes it may not kill, if you can correctly time the exposure but if you can’t, it will burn and destroy the plant.
    I had a good experience with biobizz leaf coat but if there is less than 20 days to harvest i wouldn’t do it.
    If you are that close just ride it out with potassium bicarbonate and h2o2. I wouldn’t risk burning my plants with uvc.
    Give a h2o2 bath after harvest. 1% solution should be good imho.
    SharkLasko and Aqua Man like this.
  11. Not sure what you intended to reference in that post. Go ahead give it a try. Again I stand by my statement. It damages DNA and permanently damages the plant. In all likelyhood you will kill it if you provide sufficient enough amount to kill the PM. But they are your plants... have at it and let us know. I hope you do some research on how to use safely that shot is extremely nasty.
    CrimsonEcho likes this.
  12. They are 4-6 weeks away from harvest. I can’t imagine spot treating this crap for that long, but I dunno if I have a choice.
    I’ve read that spraying the flowers over a long period of time with h2o2 can cause them to oxidize prematurely (I have already noticed slight browning, but nothing crazy), so I’m not sure if I wanna keep using that.
    Using Armor Si as a foliar spray did pretty much nothing.
    Will spraying with baking soda be gentler to the flowers? At what concentration?
    Thanks for the replies guys.
  13. The 4th and 5th reply in that post discuss the science of using UVC light to kill PM.
    I know it’s dangerous. I thought it may be more commonly used than I am finding, but everyone is just scared to death of it. There are plenty of articles supporting these type of lights to sanitize in horticulture, but it doesn’t seem like anyone messes with them.
    Aqua Man likes this.
  14. For good reason. They destroy DNA and can cause cancer
  15. CrimsonEcho

    CrimsonEcho Premium Member Supporter

    Dude in that thread there is an article that says, just a quick once over with 11w uvc can kill spores, i don’t know if it’s true or not but how slow or how quick?
    Also, again, it says use it regularly, so not a real cure if you cannot get to the root of the problem.
    Meanwhile potassium bicarbonate is perfectly safe for you and your plant, so is h2o2, don’t spray under the lights.
    I did 1 tsp per liter before with potassium bicarbonate, had no negative results.
    Try on a smaller scale first.
    Not baking soda by the way, thats sodium bicarbonate. That works too, but i read potassium bicarbonate is better for couple of reasons.
    Aqua Man likes this.
  16. Lol because your using the wrong stuff. Procidic2 or Regalia bye bye pm. Both safe for flower, but if you use in early veg you won't have the problem in the first place. Oh and air flow, air flow, air flow can't stress this enough. If you can light a bic lighter and the flame doesnt nearly go out, then your not moving enough air. Happy Growing
    Jack og, Aqua Man and CrimsonEcho like this.
  17. I have read about Regalia, but haven’t heard of procidic2. They are both hella expensive, but worth it if they actually work. I was hesitant to buy something that’s 6 times the price (or more) of what I’ve tried and have the same results.
    Aqua Man and CaliRooted like this.
  18. Yes both are expensive but they absolutely work. Procidic2 was the first for Cannabis use label on the market out of Colorado. I've been using for 2+ years pm free. The Regalia is just a good but I perfer to water that in early veg. You must treat systemically to cure your pm period and both of these accomplish that. Ive used everything over the years and these 2 products are where it's at.
    Jack og and Aqua Man like this.
  19. CrimsonEcho

    CrimsonEcho Premium Member Supporter

    100+ dollars for a gallon. Wow! And just for knotweed extract and surfactant if i am not mistaken.
    I may try a knotweed ferment, even if i buy the weed i think it will be way cheaper per gallon.
    Aqua Man likes this.
  20. 100 bucks isn't shit for how much money and time we put into these plants, think about it. 100 bucks to keep months of hard work pm free PRICELESS!! That hippie stuff doesn't work been there down that. Happy Growing
    Aqua Man likes this.