Tracking a new problem for me

[PacificNorthWest]

Powdery Mildew?

Been growing in this tent for about 3 years now and I have yet to see this. I did have a circ fan go down that I didn't replace so maybe contributing factor there? I have massive intake and exhaust...Dehumidifier running in the basement maintains 50-55% RH.

I've seen mild powdery mildew on my outdoor plants and it never seemed to be too much of a problem. Always on the lower branches near the ground...and never spread much.

Today as I was inspecting my 4x4 canopy...I noticed these white spots and I'm not really sure what to do from here. Thankfully its only prevalent on one of the 6 plants. But fungus is fungus right? It's probably everywhere by now. I think I'm about 4 weeks into flower.

Any suggestions? Maybe a fungicide spray? Too late into flower for that?

Please guide me you marijuana experts.

 

[PacificNorthWest]

I think I know how this happened. I recently added a thermostat to my tent. When it got too hot a big exhaust fan kicked in and exhausted to outside. When big exhaust fan wasn't running, I was inadvertently pulling in cold/wet outside air into my tent via the big exhaust fan duct (no check valve).

Anyway, fixed that. Now how to make the girls happier?

 

[Carcass]

A 1% citric acid spray is the best, for a more permanent fix- but for right now (unless you've already got the citric acid) a spray with vinegar will kill a lot of it (25% vinegar/ 75% water) but you'll have to spray with it every day.
Add a few drops of dish soap to the spray- it makes it "stick" to the plant a little better.
Citric acid is used in cooking, so you may be able to find it in a grocery store- if not, it's pretty cheap on Amazon- you don't need much, a little 4oz pkg will last a very long time.
I battled PM in my outdoor grow last year- it's a real pain- I never got it to go away completely, but
spraying kept the damage to a minimum.

 

[PacificNorthWest]

A 1% citric acid spray is the best, for a more permanent fix- but for right now (unless you've already got the citric acid) a spray with vinegar will kill a lot of it (25% vinegar/ 75% water) but you'll have to spray with it every day.
Add a few drops of dish soap to the spray- it makes it "stick" to the plant a little better.
Citric acid is used in cooking, so you may be able to find it in a grocery store- if not, it's pretty cheap on Amazon- you don't need much, a little 4oz pkg will last a very long time.
I battled PM in my outdoor grow last year- it's a real pain- I never got it to go away completely, but
spraying kept the damage to a minimum.

Thank you thank you!

So a little dr. bonners...with some citric acid. Check!

How many applications do you figure with the citric acid solution?

 

[Carcass]

Well, my citric acid didn't get here till harvest day, so I used the vinegar all the way to the end...I think with the citric acid you only need to spray once a week or so ,but I'm not sure- Maybe @InTheShed will chime in
with that info.

 

[PacificNorthWest]

Wonderful thank you both. Love it here!

 

[InTheShed]

Thanks for the tag carcass!

So a little dr. bonners...with some citric acid. Check!

How many applications do you figure with the citric acid solution?

It's a tiny bit of dish soap, like drops, compared to the amount of water. Dr Bronners is an oil-based soap and oils will brown your pistils.

My 1% citric acid recipe is:
500ml distilled water
5g food grade citric acid
4-8 pipette drops of dish soap
Scale as needed.

Shake well and spray the entire plant: leaves, stems, flowers, and I even pull buds away from the stems to get where the spores hide.

Since you're in a tent and can't pinpoint the source of the PM, I'd say every three days or so. It kills it where it lands, but doesn't kill what it doesn't touch.

I'd turn off the fans for 20-30 minutes to let it work before the fans evaporate it away.

 

[Carcass]

Thanks for the quick response, Shed..
.hopefully, I never have to use my citric acid, but I've got plenty if I ever do!

 

[PacificNorthWest]

You guys. Dammit. You guys are good! I will update on this one for sure.

 

[013]

Nicely done