PM 3 weeks away from harvest

V

Vdxiii

Active Member
Hi everyone,

I have a sour diesel that is 2-3 weeks from harvest. Noticed an outbreak of Powdery Mildew on many leaves, from the looks of it already started and I could find it in more than 10 spots on the leaves and close to the buds. What is the best course of action here?
Can i use H2O2 or Baking Soda for the remaining couple of weeks? Would Milk work without bud rot?
Should I go find some potassium bicarbonate? any tips or good recipes please?
Thank you all so much. With your previous help with other threads i already harvest two other plants, this is the final one and we are close the finish line :/
 
I'm about a month away from an outdoor plant being done and I've been spraying it with a potassium silicate foliar and haven't had any Pm or mold and it's been raining and cold at night here in the Pacific Northwest. I stopped using it on my squash plants awhile back and they started getting PM about a week after I stopped. So far it's been effective and I plan on spraying it right up until harvest. I don't know if it will affect the taste of the buds but I plan on washing them and won't know until it's all dried. But I don't see how it can be that bad as there are no oils or anything in it.

We had a day without rain today so I mixed up a gallon and sprayed the plant until it was dripping. I'm more worried about bud rot than PM.
 
Vdxiii said:
@xtsho I already sprayed it all with H2O2. I have ordered Potassium Bicarbonate from Amazon coming in 3 days :/
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You gotta do what you gotta do. I don't believe in spraying anything during flower but it's either that or lose the plant to rot and mold. So I'm spraying. We'll have to wait and see if it makes it taste nasty.
 
I'm with you guys. I'm douching my girl with S. Ag BT mixed with bicarb salt tonight. Starting to see small spots of rot and would really like to keep her going 'til the end of the month, if possible. FWIW, a couple of papers I've seen (here's one; https://www.researchgate.net/public..._casual_agent_of_grey_mould_of_kiwifruit#read) make a good case that the Ammonium form of the bicarb salt is about 10x more effective than the Na or K, and Ammonium Carbonate is even better.
 
@graying.geek That's a very interesting research ^ Great dig :)
@xtsho got a feeling we will all make it to end of this marathon, but which method will have affected the bud the most is the question IMHO :)
 
xtsho said:
I'm about a month away from an outdoor plant being done and I've been spraying it with a potassium silicate foliar and haven't had any Pm or mold and it's been raining and cold at night here in the Pacific Northwest. I stopped using it on my squash plants awhile back and they started getting PM about a week after I stopped. So far it's been effective and I plan on spraying it right up until harvest. I don't know if it will affect the taste of the buds but I plan on washing them and won't know until it's all dried. But I don't see how it can be that bad as there are no oils or anything in it.

We had a day without rain today so I mixed up a gallon and sprayed the plant until it was dripping. I'm more worried about bud rot than PM.
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Good to know. I'm doing the same this year until early bloom.

Aren't you concerned about excess silicate inhalation, if you're spraying that far through?
Might give you a pretty nasty cough. Besides the other health risks.
Would likely be fine for eating.

Only ask, because it doesn't seem to be something growers are regularly spraying through to harvest. And i'm curious using it myself.
 
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Aussieaceae said:
Good to know. I'm doing the same this year until early bloom.

Aren't you concerned about excess silicate inhalation, if you're spraying that far through?
Might give you a pretty nasty cough. Besides the other health risks.
Would likely be fine for eating.

Only ask, because it doesn't seem to be something growers are regularly spraying through to harvest. And i'm curious using it myself.
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Well that's a good question. I've done some research but it's use as a foliar for PM and fungal prevention is rather new. I'm only spraying it after it rains and there is a break in the weather. I'm only using enough to raise the pH to a level that the spores can't grow. And with the rain anything left should hopefully wash away. I don't see how it could be any worse than other sprays. I'm also going to wash the bud before drying. But I will probably stop at a minimum a week before I chop depending on the weather.

I do have some concerns but I'm not all that worried. I typically do not believe in spraying anything during flower but it's either spray or I might as well just chop the plant up now and throw it in the compost. As you said it would be fine for edibles. My ladies been wanting me to make her some gummies and chocolates anyway. But if the plant rots it won't be fine for anything.



"This regulation establishes an exemption from the requirement of a tolerance for residues of potassium silicate in or on all food commodities when applied/used as a fungicide, insecticide or miticide so long as the potassium silicate is not applied at rates exceeding 1% by weight in aqueous solution and when used in accordance with good agricultural practices. PQ Corporation submitted a petition to EPA under the Federal Food, Drug, and Cosmetic Act (FFDCA), as amended by the Food Quality Protection Act of 1996 (FQPA), requesting an exemption from the requirement of a tolerance. This regulation eliminates the need to establish a maximum permissible level for residues of potassium silicate."



 
Prepare your plants immune system in veg witha combination of copper sulfate, lime ** edit and obviously water ** foliar. Or you can buy a bottle of liquid copper. It's blue. Light mixture for prevention heavy for battle.
 
This stuff is gentle too. Haven't had PM in a while but maybe look into a simple solution. Spray only once - chart the heal. Spray again only if still present
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Skoal said:
You are also gonna want to do a hydrogen peroxide wash after before you dry the buds.
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Obviously yes, I sprayed it last night and again this morning. I could tell late in the afternoon that it was bothered.. The tips of the sugar leaves and the calyxes started darkening... I am going to start potassium bicarbonate once I receive it this Sunday... Maybe I will need to hit it with H2O2 again from here to Sunday...I still dunno.
 
Vdxiii said:
Obviously yes, I sprayed it last night and again this morning. I could tell late in the afternoon that it was bothered.. The tips of the sugar leaves and the calyxes started darkening... I am going to start potassium bicarbonate once I receive it this Sunday... Maybe I will need to hit it with H2O2 again from here to Sunday...I still dunno.
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You gonna have to spray on a regular. And do the final wash after with a rinse. You’ll be fine. Happened with my outdoor. I saved the entire harvest except for maybe one branch out of laziness. Was still about a pound.
 
I wouldn't spray anything that started as a solid on ripening buds. You're gonna end up with the bicarbonate solids in your joints, yuck!

H2O2 should be ok, but I wouldn't spray anything else past week 3 of flower, unless you can somehow keep the spray completely off of the flowers.
 
After what @Aussieaceae said in a previous post I have thought about spraying potassium silicate some more. While I do think it is effective at preventing PM, I think it should be stopped at least 3 - 4 weeks prior to harvest. I did some research on potassium silicate residue and combustion. There is very little information available on the topic but I do know that the silca forms a thin layer on the plant material. Like most things, that residue will degrade and break down over time so 3 - 4 weeks should be sufficient time for it to dissipate and with a final washing of the bud there should not be any remaining residue on the bud.

I wanted to make this post to amend my "Spray up until harvest comment" I made previously. I do not think that is a good idea and I will not be doing that. One of the good thing about sites like this is that when questioned it allows you to rethink what you're doing and after further consideration I do not feel that spraying potassium silicate up until harvest is a good idea.

But I have found a solution for my 8 ft outdoor plant. I forgot that my living room has a vaulted ceiling so I'm just going to bring it inside at night and when it rains. My main concern hasn't necessarily been the rain but the cold humid nights. Fortunately the plant is in just a 3 gallon pot so it's easy to move.

Anyway, good luck to everyone else trying to keep their outdoor plants from rotting away. I shouldn't be dealing with this issue but I thought I had planted a quick flowering Ruderalis Indica but instead planted a Ruderalis Indica + Panama cross I made. I will not be growing this strain outdoors in Northwest Oregon again. It takes too long to finish and makes absolutely no sense growing it outdoors as it takes too long to flower.

Strain selection when growing outdoors should be based mainly on finishing time. It makes absolutely no sense to grow a strain that won't finish before the weather becomes a problem. Which is why I've been working on a few crosses that finish in September. A friend that grew a cross I made harvested his outdoor a few weeks ago without any bud rot and now is sitting on a couple pounds of sticky bud. I made a bunch of feminized seeds of that strain and will be growing one myself outdoors next summer along with some auto's that I know with finish by the end of August. I'm not a big auto fan but they are good for outdoor grows. I'd never grow them indoors but they do have their place. I'm also thinking about working on my own auto as I have some landrace auto/semi auto genetics to work with.

Good luck to all with your harvest.
 
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