I have dealt with powdery mildew outside but this is in a tent and it’s crowded in there. It makes me nervous.
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I have never had to deal with PM, so I don’t have any advice, but wanted to pass along my best wishes. I’ve seen so many people struggle with it, I hope you get it resolved quickly and without too much stress.
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Thanks for the help and kind wishes guys.
I’ve been pretty lucky my last few cycles.
I think I might need to switch to shorter veg times because my tent has been really full the last few goes and I’m playing with fire.
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I hear ya. My tent is packed enough right now and humidity is high enough that I’ve become concerned about it. I recently bought another fan for under-canopy air movement, and I’m hoping that’s enough to let me continue to avoid this particular problem.
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I have a humidity sensor in my canopy and it’s been a steady 55-58% for awhile. The ambient humidity is much lower.
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Sorry to hear you’re seeing some PM. I’ve been battling this shit chronically for months now. Defol is definitely important, as well as airflow. If you’re just seeing a bit pluck any infected leaves and maybe try a light hydrogen peroxide spray .I forget the amount of h2o2 tbh but there’s tons of recipes online. Use a small amount of wetting agent and be sure to spray the entire plant top to bottom.
If it persists the only thing I found that worked that I could spray in flower (if hp doesn’t work) is potassium bicarbonate. I used it at (I believe) 3tbsp per gallon with a tbsp of veg oil and a tsp of dish soap.
Keep in mind this WILL burn the pistils on the plant and seems to effect yield a bit. The bud is safe to smoke, but I still would wash them at harvest just to be sure. You’ll need to spray again weekly while they’re flowering or it will come right back.
Going forward you’ll need to extra vigilant and keep an eye out for any signs of it. I found a sulfur spray worked great in veg, and hitting them with it just before they formed flowers kept it at bay for a while. The only thing is after several applications the plants started growing like mutants from the sulfur so use it sparingly if possible.
Also keep in mind that some strains are more resistant than others, so if you don’t see it showing up on your NL it probably has resistance and you should dump the WW.
There are lots of expensive sprays that are supposedly effective but I never tried as the cost was too high to use all the time. I started a PM thread that was basically inconclusive, but there’s lots of info and suggestions:
Good luck and hopefully you can kill it, I HATE powdery mildew.
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Thanks for this info and your help beacher.
So I checked my tent again and the mildew has spread big time. It’s very obvious with even a passing glance. I’ve been manually removing affected leaves/buds but it’s not enough:
The really bad news is that it’s spread to the other WW. It’s strange, it’s developed on the outside of the plant and not the dense internal canopy.
A few little spots I might be able to correct but this is out of control. The plants are too big to realistically spray.
I’m going to kill them to protect the NL. This means that I’ll only harvest a 1/4 pound instead of a pound.
I’m still half asleep so I’ll make this final decision in a few hours but it seems to me to be the wise option.
Fuck.
Thanks for the input guys.
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A thought:
Is the point of using the bicarbonate to alter the pH to the point it is inhospitable to the mildew?
If this is the case then why not just use pH up to reach this point? When my lady makes pretzels she uses an alkali bath at 9.5 for browning.
I think it’s too late for my current plants but thought it might be worth mentioning. @beacher is this idea somewhere in your thread?
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Ya it looks like it’s coming in quickly now. It spreads very fast. Spraying big plants can be tedious, but it is possible. I prop the pot up on something to angle the plant to get the bottom of the leaves, then prop the other side for the bottoms again then blast the tops and sides. I could understand just hacking them to protect the others though.
And yes, as far as I can tell that’s the idea with the potassium bicarbonate. Why that vs any other alkaline substance I can’t really say, but I do know that people say baking soda doesn’t work nearly as well even though the effect should be similar. Also commercial fruit growers use potassium bicarb so there must be something about it that makes it more effective.
I’ve also read that calcium and silicate (in feed water) can help the plant to be more resistant but I didn’t notice much of a difference with them.
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Dang that PM. I feel for ya @Foreigner
I’ve battled the dreaded PM.
Every grow since, has me paranoid it will surface and ruin my day…week…month.
Watched beacher go thru hell.
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Ya it’s tragic lol, I can’t wait to get back to a normal house where this won’t be an issue again. I never had it in my growing life before this, I think environment plays a huge role.
@Foreigner also keep an eye on that NL and if it never shows up you probably have a resistant plant which is gold. You could at least make that a staple and try other strains as you go.
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Sorry to hear about the spread man… Sucks…
I’ll definitely be keeping an eye hoping you get it figured out. Good luck dude!
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That’s gotta hurt. Probably the right move, though.
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If you put them outside in sunlight & keep them arid as possible you’ll kill it enough that new growth will be unaffected…remove older stuff ASAP. (worked for me, but indoors I just don’t have the experience)
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So the NL is developing powdery mildew also 
It’s patchy and irregular but I have no doubt that it’s going to spread fast.
The good news is that this NL is a 49 day strain and I’m at day 41 so I don’t have too far to go. As long as I can slow the PM down a little I should be ok.
I’m going to make an alkali spray at a pH of 8.5-9 using pH up and drench the plant thoroughly.
If that doesn’t work I’ll use the baking soda method.
As I said I only need to buy myself a week so it should be ok.
The real question is how do I sanitize my tent when this run is finished.
Wish me luck.
All the best.
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F man, you don’t need that! None of us do. Best of luck.
What I have done.
Depending on the surface, I used alcohol, bleach, vinegar. Separately! Never combined!
Sulfer burn entire 2 car garage and my grow spaces within.
I have also sulfer burned the garage just before flipping.
Major bummer when that chit hits.
Edit. I also “bug bomb” the garage before starting up.
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I was thinking about using bleach to clean up my tent when all is said and done. I don’t think I can use a sulphur burn because I live in an apartment.
Also, something just exploded down the street from me. The flames were 30’ high. I felt the boom:
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Don’t look at ME! 
Yeah. That’s not a good combination IMO.
For bugs, heat is the cleanest thing I know of. 
But PM probably needs actual fire. (not 'dissing your weed! 
)
Sorry.
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My weed is fire! 
Seriously though I’m going to take some heavy action when this is all said and done.
I’m not sure what that action will be but it might be something like bleach and shutting down for awhile.
I’m also considering why this might have happened and am encouraged by some of this thinking.
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