Is this powdery mildew?

This topic has 21 replies, 4 voices, and was last updated 1 year, 2 months ago by mrgrowit.

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September 7, 2023 at 4:53 pm #2748

GrowerGamer
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Is the white on the leaf shown below powdery mildew? I only ask because I have not encountered it before and it doesn’t look “powdery” to me but it has been showing up on more leaves. I clipped all leaves off that had it and sprayed the remaining leaves with a 40/60 milk to water mix after seeing it recommended and it seems to have slowed dramatically. I’m in the northeast so only a couple of weeks from harvesting this outdoor crop and I’d hate to lose it…

September 8, 2023 at 11:07 am #2753

CamZ
Moderator

That is what it looks like from the photo. You could try a stronger milk spray. Truthfully, unpasteurized milk is what you want. I believe it’s the white blood cells that kill the bacteria. In pasteurized milk everything is dead. You can also use a spray from southern ag that is concentrated bacillus amlyoliquefaciens. Those are the only 2 safe methods I’d use. I would budwash regardless.

September 8, 2023 at 4:28 pm #2754

GrowerGamer
Participant

Okay, thanks for the confirmation. I’ve actually brought them inside since they’re in pots and the central AC is keeping the humidity low enough inside (40-50%) that it seems to have slowed dramatically or stopped progressing altogether. I guess I may keep them in here for the foreseeable future since the humidity outside doesn’t look like it drops below 80% anytime soon. If I were to plant in-ground next season, what’s the best way to prevent it? Neem oil spraying throughout the season and adding silica?

September 8, 2023 at 10:13 pm #2755

CamZ
Moderator

Your best bet is finding strains that are resilient to it. Silica can help too. If you get monosilicic acid and mix it with water it can strengthen the cell walls of the leaves considerably when used as a foliar spray, which can help prevent pm too.

September 9, 2023 at 11:32 am #2757

GrowerGamer
Participant

Awesome, thank you for the suggestions!

September 9, 2023 at 4:15 pm #2766

mrgrowit
Keymaster

Bummer! I hope it is low impact. Here is an article I wrote all about powdery mildew and treatment methods:
https://mrgrowit.com/post/powdery-mildew-on-cannabis-plants/

Hope this helps!

September 10, 2023 at 10:53 pm #2768

GrowerGamer
Participant

Thank you! I’ll definitely be trying some of the suggestions. I’ve got a bottle of the Southern AG organic fungicide arriving tomorrow that CamZ suggested. Bringing them indoors into a dry, climate-controlled environment seems to have also helped to slow the spread. At this point, I feel like I’m running out the clock in a football game.

September 16, 2023 at 2:31 am #2781

SeasonsLater
Participant

Great article. Thank you for sharing. Grow safe looks especially interesting, you can use all the way up to harvest?

September 18, 2023 at 4:09 pm #2788

mrgrowit
Keymaster

I wouldn’t spray that in flower.

September 19, 2023 at 10:24 am #2791

CamZ
Moderator

The Sothern Ag product? It’s just concentrated bacillus bacteria. I tried to comment yesterday but the robot check can’t do math correctly lol.

September 19, 2023 at 11:04 am #2792

GrowerGamer
Participant

I hope he didn’t mean the Southern AG product because I’ve already used it twice lol

September 19, 2023 at 11:11 am #2793

GrowerGamer
Participant

When I bud wash, is it recommended to leave an oscillating fan directly on the washed flowers until they’re dry to the touch? I’m really paranoid about making the problem even worse by introducing mold…

September 19, 2023 at 2:15 pm #2794

mrgrowit
Keymaster

Sorry for the confusion. @SeasonsLater was asking about Grow Safe which is linked in the article I posted. It has corn oil, soybean oil, and a few other things which is why I was saying I wouldn’t spray that in flower. I’ve never used Southern AG but I trust Cam Z

September 19, 2023 at 2:21 pm #2795

mrgrowit
Keymaster

@growergamer when I bud washed I dried at 50% RH 70F for the first 1-2 days then I was more towards 60% RH 65F. Air circulation is a must and exchanging the air at least 1x per day is also a must imo. Hope that helps.

September 19, 2023 at 2:26 pm #2796

GrowerGamer
Participant

@mrgrowit Thanks, I meant immediately after the washing to try and dry the water droplets as soon as possible. I’ll be doing it in a tent in my basement with two clip on fans hitting the inside walls and the online fan exhausting 24/7. It’s usually in the upper 60’s and around 50-60% RH year round in my basement so I’m hoping for the best. Thanks again for the tips!
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