Powdery Mildew, Sulfer and H2O2

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I've got powdery mildew on a plant that is in it's 12th week of flower, I'm going to harvest this weekend. The mildew has kept mostly to the bottom third of the plant, mostly on the leaves.

I spent most of this afternoon researching and this is what I've got.

I'm thinking of getting a surfer burner but I don't know how many sessions it takes to kill PM completely. 1: Is it safe to burn sulfer so late in the plants life? 2: How many sessions will it take?

I was also thinking of an H2O2 bath after harvest to wash away all of the PM. 3: Do you think this is necessary after sulfer burning?

Thanks for any help you can give!

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Sorry for the shitty picture, it's the best my 20 year old camera can do.



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Don't burn sulfur while flowering, bad idea. I like to mix h2o2 and water and spray affected areas in flower. Spray and rub where there's pm, should get you through to the end along with doing whatever possible to correct environmental conditions

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Thanks Mac, I definitely don't want to loose this plant after 12 weeks of flower.

I was thinking of mixing 1.5 ounces of H2O2 with 1 gallon of water, would you go more potent?

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Hobbes said:

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Thanks Mac, I definitely don't want to loose this plant after 12 weeks of flower.

I was thinking of mixing 1.5 ounces of H2O2 with 1 gallon of water, would you go more potent?

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8-10:1 water to h2o2 ratio usually, start lower and see how the plants take it. Some plants seem to be more sensitive than others, some can take a stronger ratio.

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Thanks Mac!

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I came across a neat little gizmo that I ordered this morning - a UVC hand held light that's designed to kill powdery mildew. Just sweep it across the plants and the infected areas are sterilized.

I'll let you know how it works, for now I'm off to use Mac's advice with H2O2 and a spray bottle.

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Hobbes said:

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Thanks Mac!

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I came across a neat little gizmo that I ordered this morning - a UVC hand held light that's designed to kill powdery mildew. Just sweep it across the plants and the infected areas are sterilized.

I'll let you know how it works, for now I'm off to use Mac's advice with H2O2 and a spray bottle.

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Stop powdery mildew with CleanLight USA

Stop powdery mildew with CleanLight is a website where you can find Crop protection with UV-Light against for example powdery mildew

stoppowderymildew.com

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those will kill your plants and anything else living in your grow room. only use UVC to sterilize a grow room before planting

If the fungus is on the leaves, then it is in the buds too. Since you are going to harvest in a few days, there is not much that spraying anything will accomplish. If you do burn sulfur, or spray garlic (contains sulfur) or anything else, you will want to wash your plants afterwards anyway.

So at this point I would just harvest and do the H202 dunk. It's best to not use the "typical drug-store 3 percent H202" so try to find the stronger version, and just be careful with it.

Hobbes said:

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Thanks Mac!

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I came across a neat little gizmo that I ordered this morning - a UVC hand held light that's designed to kill powdery mildew. Just sweep it across the plants and the infected areas are sterilized.

I'll let you know how it works, for now I'm off to use Mac's advice with H2O2 and a spray bottle.

.

Stop powdery mildew with CleanLight USA

Stop powdery mildew with CleanLight is a website where you can find Crop protection with UV-Light against for example powdery mildew

stoppowderymildew.com

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Click to expand...

Be careful with eye protection if you're using that. Most glasses wont filter the UV-C.

rollitup said:

If the fungus is on the leaves, then it is in the buds too. Since you are going to harvest in a few days, there is not much that spraying anything will accomplish. If you do burn sulfur, or spray garlic (contains sulfur) or anything else, you will want to wash your plants afterwards anyway.

So at this point I would just harvest and do the H202 dunk. It's best to not use the "typical drug-store 3 percent H202" so try to find the stronger version, and just be careful with it.

Click to expand...

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Thanks! I bought a 10 gallon plastic tote to do the wash and have a litre of H2O2, I'm sure that the wash will help. I think that I have a bottle of concentrate in my attic.

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Is anyone familiar with UVC's effect on THC, how quickly it'll degrade?

I'm going to do an H2O2 wash then I was going to use the CleanLight afterwards, I won't be getting it for a couple of weeks.

It's suppose to be OK to use the light up to harvest but the THC will degrade if used after harvest.

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Hobbes said:

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Is anyone familiar with UVC's effect on THC, how quickly it'll degrade?

I'm going to do an H2O2 wash then I was going to use the CleanLight afterwards, I won't be getting it for a couple of weeks.

It's suppose to be OK to use the light up to harvest but the THC will degrade if used after harvest.

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Be careful when drying washed buds they will be way more prone to mold. Perhaps if you have a salad spinner you could spin off the excess water before the drying process
I wouldn't worry about the UVC so much on the buds, the wash will take care of it but the light will be great to disinfect the grow area with

Hobbes said:

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Thanks Mac!

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I came across a neat little gizmo that I ordered this morning - a UVC hand held light that's designed to kill powdery mildew. Just sweep it across the plants and the infected areas are sterilized.

I'll let you know how it works, for now I'm off to use Mac's advice with H2O2 and a spray bottle.

.

Stop powdery mildew with CleanLight USA

Stop powdery mildew with CleanLight is a website where you can find Crop protection with UV-Light against for example powdery mildew

stoppowderymildew.com

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Well, just looking at that link description, it's difficult to trust a site that says you need a "pesticide" for fungus control instead of a fungicide!

rollitup said:

Well, just looking at that link description, it's difficult to trust a site that says you need a "pesticide" for fungus control instead of a fungicide!

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LOL! Just noticed after rereading.

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After a day of research and reading posts in this thread I've come up with a plan, tell me what you think.

1. Wash the harvest in H2O2 solution and rinse off the dead mildew.
2. Vaporize sulfer in the then empty 3x3 tent that the PM Sluracane is now in.
3. Vaporize sulfer in my flower tent - plants at 2 weeks of flower.
4. Run a daily sweep of tents and plants with the UVC CleanLight.
5. If PM returns to harvested Sluracane buds I'll hit them with UVC.
6. Put fans in the back corners, under the canopy, where there is little air flow.

Just so I have it straight, it's OK to vape sulfer in the first couple weeks of flower?

How long do I burn sulfer for a 4' x 4' tent?

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This is the infected plant that I'm going to harvest within a week or two, it's in the 12th week of flower (9 week strain).

I scoped the trichs at the bottom of the plant and at the top - there's almost no PM at the top.



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I scoped buds from the 3 plants that I've already harvested and there's a trace amount of PM in one of the cans - Blue Dream that had buds touching buds, poor support.

Will this breed in my can or does the PM stop spreading when the plant is dead?

I'm getting a CleanLight UVC light probably next week. I can sterilize all of the buds but the light will degrade THC.

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Hobbes said:

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This is the infected plant that I'm going to harvest within a week or two, it's in the 12th week of flower (9 week strain).

I scoped the trichs at the bottom of the plant and at the top - there's almost no PM at the top.

View attachment 4658194

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I scoped buds from the 3 plants that I've already harvested and there's a trace amount of PM in one of the cans - Blue Dream that had buds touching buds, poor support.

Will this breed in my can or does the PM stop spreading when the plant is dead?

I'm getting a CleanLight UVC light probably next week. I can sterilize all of the buds but the light will degrade THC.

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If there's moisture in the buds and they're in a sealed container it will spread. Maybe wash them. I've only had pm come back once after bud washing and it turned out it was deep in the buds.

here's a good read on how not to get WPM

Nizza said:

here's a good read on how not to get WPM

Powdery Mildew & Foliar Remedies

Powdery Mildew is a fungal disease that affects a wide variety of plants. PM is one of the easier fungal diseases to identify as its symptoms are quite distinctive.

oaksterdamuniversity.com

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That was a good read, thanks!

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macsnax said:

If there's moisture in the buds and they're in a sealed container it will spread. Maybe wash them. I've only had pm come back once after bud washing and it turned out it was deep in the buds.

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I dread the thought of washing curing buds but it needs to be done.

Have you looked at the CleanLight link above? I could sterilize the surface of all the buds, at a cost to potency. But at least I wouldn't have to wash the buds.

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I just spent some time scoping the 3 strains that I've already harvested.

The first two, Lemon Haze and OG Kush are free of any PM. The third, Blue Dream, has trace amounts of PM, just individual spores on the buds and trichomes.

I'm going to keep an eye on them, either wash or UVC Blue Dream and wash Sluracane, the 4th strain I'm growing.

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