Powdery Mildew

So I have powdery mildew. I have been spraying with Serenade but it keeps coming back. The humidity outside is 80-90 percent sometimes and I don't have anywhere else to pull air from. I got an air cooled hood so I could keep the temp down without having to exhaust the room. I have a dehumidifier but it just runs all day and the humidity still gets up to 60%+ sometimes. The humidity hasn't been quite as bad the past few days and it seems to have slowed the mildew down but it still comes back. The only thing I can think of would be to buy another dehumidifier but I don't really want to spend the money. I only grow for myself so I'm not making any money from this.

The plants are 30 days into flower now and I need to do something. Should I just give in and buy a dehumidifier? Any other ideas of what I could do? If I keep spraying or even use a sulfur burner will it just keep coming back since the humidity is too high? Would an air filter help at all?

I would REALLY appreciate any help or ideas.

I have 10 Hawaiian Mango plants under a 1000 watt HPS in an 8x12 room. If you need anymore details let me know.

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No ideas? Anybody?

Excel lg has worked wonders for me in this grow, but it's systemic so I would only use it if ur planning on flowering for at least a full three weeks
out.
PurfectStorm

dogsled said:

So I have powdery mildew. I have been spraying with Serenade but it keeps coming back. The humidity outside is 80-90 percent sometimes and I don't have anywhere else to pull air from. I got an air cooled hood so I could keep the temp down without having to exhaust the room. I have a dehumidifier but it just runs all day and the humidity still gets up to 60%+ sometimes. The humidity hasn't been quite as bad the past few days and it seems to have slowed the mildew down but it still comes back. The only thing I can think of would be to buy another dehumidifier but I don't really want to spend the money. I only grow for myself so I'm not making any money from this.

The plants are 30 days into flower now and I need to do something. Should I just give in and buy a dehumidifier? Any other ideas of what I could do? If I keep spraying or even use a sulfur burner will it just keep coming back since the humidity is too high? Would an air filter help at all?

I would REALLY appreciate any help or ideas.

I have 10 Hawaiian Mango plants under a 1000 watt HPS in an 8x12 room. If you need anymore details let me know.

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Hi, *warning novel follows*
...so what are you using to circulate air in the room? Just the venting fan that's hooked to the hood? Not enough if that's the case.
My grow gets powdery mildew too. (stick with Serenade it IS the best! Use it every 7 days and I apply it sometimes with a foam paint brush to minimize bud spray. Spray all new plants going to flower too if you rotate. I wouldn't let up.)
Otherwise...and in addition, I have to really work to lower the humidity by leaving the vent fan on 24/7 and increase the vent fan speed on the variable speed dial and add a couple more occilating fans to REALLY circulate the air in the space. I also try to raise the temps during the lights on cycle to dry the whole space out a bit more. I've done this by detaching the vent line from the light hood. I still leave the opening of the vent duct at about the level it was at when attached to the light but this configuration lets the light warm the space and evaporate some of the moisture that's just hanging around.
Other ideas are... don't keep the soil soaking wet, most growers tend to over water a bit. Try to dry your plants to almost the point of wilting before you water again, the High humidity is also playing a role by slowing the actual transport of water out of the leaves...moist air doesn't wick water out as quickly as dry air, so it's possible that your regular watering pattern is a little too much when the humidity is high, which in turn results in lots of wet soil longer than usual which makes things extra humid at night....if you're growing hydro don't water late in the light cycle, let them dry a couple to 3 hours before lights out. Hope this helps a bit. Happy Gardening! GrowIT!

dogsled said:

No ideas? Anybody?

Click to expand...

im guessing u got a cheap ass dehumidifier..right? where i live its about the same 80% outside and i got a 30-40 pint dehumidifier that does the job for me..i got PM this grow and it fuked up one of my plants but i saved the others with serenade and the dehumidifier..which ever one is the worst id just take it out..i learned the hard way..i dried the buds and the smell made me wanna puke, ended up being a waste of space cuz im probably just ganna throw em away or give it away

Once you have it no amount of humidity control or serenade will bail you out. Seriously go to ur local hydro store and pick up some systemic fungicide. It's the only way possible now short of a wind tunnel. I've found pm can continue to thrive in very low humidity and serenade will do nothing but knock it back for a few days. I will never go back to these bandaid procedures.

out.
PurfectStorm

Though some folks use systemic fungicides to treat Powdery Mildew I would really be reluctant to ingest in anyway a bud or food that was treated at some point with a systemic. It's pretty much always going to be 'IN' the plant in order to do it's job. So that means by inference, that it will eventually end up 'IN' you.
Serenade is the QST 713 strain of Bacillus Subtilis. The Bacillus is a naturally occuring soil micro-organism. Not known to cause food poisoning in humans, not a human pathogen what so ever. Most systemics are chemically derived. Look up their ingredients and see how good they are for the human body and which ones are rated by the OMRI for use up to and including harvest...not too many I think you'll find. SAFE gardening! GrowIT!

If you'll read more about how systemic fungicides work, they only are "in the system" for three weeks. Therefore, I will let you use the bacillus, and laugh when your heavy drenching of foliage with the stuff does nothing but boost you're humidity, waste your money, make your grow room smell like shit.

All Excel LG is mono and di potassium salts of phosphoric acid, i havnt used any of the fungicide in weeks, and my grow is still looking nice and extra green compared to the last batch, not a hint of PM in sight.

All i'm saying is that in some areas (nor cal included) sometimes more drastic measure need to be taken and some grows are simply not meant for a sulphur vaporizer.

out.
PurfectStorm

I struggled with pm as well. Once your plant has it you cannot get rid off it. It lives inside the plants, the white powder is just the flowers/spores. Serenade and sulfur smell terrible and are not really options for people growing in their rooms. I used a product called GREEN CURE, no smell and it worked better than serenade. Also buy more fans!!! and if your gonna get a dehumidifier, just buy an ac with dehumidifier function instead. An AC unit is the same thing as a dehumidifier only it vents it's hot air outside. don't be fooled.

good luck

PurfectStorm said:

If you'll read more about how systemic fungicides work, they only are "in the system" for three weeks. Therefore, I will let you use the bacillus, and laugh when your heavy drenching of foliage with the stuff does nothing but boost you're humidity, waste your money, make your grow room smell like shit.

All Excel LG is mono and di potassium salts of phosphoric acid, i havnt used any of the fungicide in weeks, and my grow is still looking nice and extra green compared to the last batch, not a hint of PM in sight.

All i'm saying is that in some areas (nor cal included) sometimes more drastic measure need to be taken and some grows are simply not meant for a sulphur vaporizer.

out.
PurfectStorm

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LOL! Thanks for the education, but I already have read up on the 'food grade' Potassium salts used for fungal control. It's just a choice, and we disagree, no worries. Sure I trust the FDA, they never do anything that would intentionally hurt someone huh? They're always on top of things huh? No Lobbying money being spent there I bet.
Meanwhile I'll stick to ALL OMRI ORGANICS. The smell of Serenade dissapates after a day, you can apply it with a brush if you don't like spraying it, and if you buy a big enough vent fan up front and pay attention to cleanliness and avoid getting too greedy by packing in too many plants for your space, you'll do just fine. Best of Luck to you! Happy Gardening! GrowIT ORGANICLY!

also, remeber that powdery mildwer and DOWNEY mildew look virtually identical to the untraned eye when they both are young. remeber, what works for downey mildew doesnt always work on powdery mildew.


i use a systemic (exel LG ) for downey mildew and powdery mildew both, and generally works great, but its working great is also strain dependant. ive had strains ( such as U2 kush) that had bot powdery and downey, and have had systemic treatments kill one while doing nothin for the other. no one product on the market is a "wonder product" that will kill everything, but neem seed oil comes close. what i generally do is i will treat systemically with exel in both a foliage spray and also a systemic treatment. if anything comes back, i then hit them with neem oil which generally takes care of it. the neem oil is great for just about everything pestwise that afflicts and attacks cannabis.

remeber, powdery and downey mildew are not the same.

That shit sucks. Don't let it get to your buds. You should google milk and powdery mildew. Turns out that milk, in a 1part milk to 9part water, helps the plant build ammunity to the diease and acts as a folier feed also. Hookdonchronics brought that to my attention yesterday. Good luck.

usinwatts said:

That shit sucks. Don't let it get to your buds. You should google milk and powdery mildew. Turns out that milk, in a 1part milk to 9part water, helps the plant build ammunity to the diease and acts as a folier feed also. Hookdonchronics brought that to my attention yesterday. Good luck.

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yes, milk and water works, as does baking soda and water, BUT the problem you run into is they dont CURE shit. all they do is kill the powedery mildew that you actually see. the part you see on your leaves isnt the whole thing. once your plant has powdery mildew or downey mildew, its ALWAYS GOT IT, until you treat systemically and kill the problem INSIDE THE PLANT. the mildews micilieum (not sure of the spelling) extends well into the plant itself. surface preperations dont do anything to kill it. exel LG only stays in your plant for about 3 weeks, and its foodsafe. ive used it before,durng and after harvest and never had any issues. using milk or baking soda and water may make the plant LOOK like its void of any fungus, but its still present. unless you treat systemically, youll be smoking the mildew even if it looks clean.

the main cause of either is high humidity. best thing to do instead of fighting the stuff is to get ourself a decent free standing dehumidifier with a humistat .

why would you say that exel sucks and not to get it on your buds? i spoke to the company in length about it, and they told me that it is designed to use on vegatables and is completely food safe if used as directed.

I said it once.... I'll say it again .........PM IS HERPES FOR WEED...NO CURES JUST ALOT OF TREAMTMENTS

greencure for flowering....oderless.... organic.... works for 10-12 days......milk, h202 works for 4-5 days

Eagle 20 ew for vegetive ....30 day systemic.....kills the pm from inside the plant

You HAVE TO CLEAN YOUR ENTIRE GROW ROOM!!! Walls, floors, ceilings, lights everything....1/4 cup bleach per gallon of water......1 spore and you have it again

Powdery mildew spores float in the air and are everywhere. They need the proper conditions to germinate: a surface that contains nutrients on which they can grow, temperatures over 60?F (16-20 C), high humidity and a slightly acidic environment. Once the spore senses these conditions , it germinates, sending out a hyhae which seeks out a stomata. It enters the tissue and lives off its nutrients, eventually killing the tissue. The downy mildew powder you see on the leaf is the reproductive organ of the plant, which is releasing spores into the air.

Once the spore germinates, it survives in a wider range of conditions. Lowering humidity does not eliminate the infection.

Yes.... infected Mother plants WILL pass the pm to the clones/cuttings...usually the PM will not show itself until your in flower

PurfectStorm, Help! I have powdery mildew on my plants from veg to full flowering and bought the Exel LG Fungicide, but I can't figure out from the directions exactly how much of it to put into my reservoirs. I have 40 gallon reservoirs and I grow in rockwool (both ebb and flow and Nutrient Film Technique).

-How much do I use for a 40 gallon reservoir?
-Do you use it also as a foliar spray, and if so, how much for a quart sprayer and how often? Every week?

Do you use it all the way up until harvest, or would it leave a nasty taste?

Thanks!