Question about Potassium Bicarbonate to treat WPM

Vinny133

Vinny133

Well-Known Member
Currently in week 5 since flipping the lights to 12/12. Recently came across some WPM on a couple of leaves. I’ve been growing a number of years and have been fortunate enough not to have come across this problem before so I was at a loss. After some research, it appeared a simple and effective solution was to mix a tablespoon of food grade potassium bicarbonate and a few drops of dish soap with a gallon of water and spray liberally. I have been doing this and it seems to be working well but the odd spot occasionally reappears. My question is, is this stuff safe to use during flower? I did try and research the point here, but I couldn’t find anything specific on that particular aspect of it. Lots of stuff about potassium bicarbonate but nothing on whether it’s safe to use on buds you intend to smoke.

Thanks,
Vin
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SnoopingAsUsualI said:
That looks like powdery mildew to me, now potassium is a natural nute for ganja, so I guess it's safe but I cant tell how's that gonna help. Apparently, my knowledge's are insufficient for that question, now I'm really curious about it
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From what I’ve read it definitely an effective treatment. Cheap and easy but requires periodic application until harvest. Not sure if I want to smoke it though. Will probably do a bud wash as a result of having to do this. Question is, do I go to all this trouble for mediocre buds (assuming the treatment affects them) or rip them up, disinfect and start again.
 
It should be safe during flower. Best to check that a soap is being used. It should say on the bottle or bar. Detergents are made with petro-chemicals while a true soap will be made with naturally occurring oils and fats. Just my opinion but if it is just a few drops then any mild dish detergent will work without any adverse effect.

There is a good amount of references found on-line supporting the use of the potassium bicarbonate as a way to control Powdery Mildew on plants. Yes, periodic application and that has been my experience using anything to keep the mildew under control.

What I use is a mix of citric acid and water with a few drops of soap. The message from @InTheShed found in a thread on this message board and the link is below. Since that msg was posted he has changed the recipe a bit and last I heard was experimenting with totally different spray mix.

https://www.420magazine.com/community/threads/thrips.512473/page-5#post-5519939
 
SmokingWings said:
What I use is a mix of citric acid and water with a few drops of soap. The message from @InTheShed found in a thread on this message board and the link is below. Since that msg was posted he has changed the recipe a bit and last I heard was experimenting with totally different spray mix.
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Thanks SmokingWings! I went down to a 0.25% citric acid (down from 1%) mix with a few drops of Dr Bronners unscented castile soap, but since that still caused more pistil and leaf damage than I was comfortable with I continued to research and now use 0.3% canola oil mix. I posted the recipe (along with the original research of course) here:
InTheShed

Post in thread 'InTheShed Grows Inside & Out: Jump In Any Time'

After many weeks of testing, I'm here to offer my endorsement of 0.3% canola oil spray for powdery mildew (PM). And to break it all down for you, here is the Thursday update (after you've congratulated @Grand Daddy Black for his triple OTM win last night...I'll wait!).

Text, then pictorial:

As I mentioned back in March, I discovered a South Korean study from 2008 and seems well-researched and documented, and on the plus side, it's written in mostly non-technical language, dealing in percentages and ml rather than molecular weights and such...
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Potassium bicarbonate can be used in flower, but it causes premature browning of stigmas/pistils at the dose you're using, which is the most effective dose I've used.
It can also cause problems if your nutes are high in potassium, since it can act as a foliar feeding.
I don't use it in flower anymore.
 
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