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Need help re: Piperonyl Butoxide

here in oregon the pesticide LOQ for piperonyl butoxide is <2 and we’ve been consistantly testing at around .4 which is a pass. but what this means is that extractors will not buy trim and larf as that .4 will turn into a 4 after extraction which is a fail for them.

i cannot for the life of me figure out where i’m getting this substance.

not using aerosols
not using pyrethrins
only using grandevo and nukem as pesticide/fungicides.
room clean with zerotol

could it be in my water? nutrients?
i’ve called marone, flying skull and royal gold to ask if there is any chance it’s in their products.

anyone have any thoughts as to where i’m picking this stuff up?


With a half-life of 8ish hours, with a aerosolized half-life around 3.5hrs. Half-life max is around 14 days with light and whatnot. The source must be close. Are you sure someone isn’t using it without saying anything? Any nearby grows? I’d have a hard time believing it is your water since it doesn’t dissolve well.


I remember reading recently about another product causing failure for piperonyl but I can’t remember what product it was! I will keep looking though. I have seen some false positives from farms in Oregon that I know weren’t using it and they ended up sending samples to three different labs that all came back clean. Not sure where the first sample may have been contaminated but unfortunately, there are going to be a lot of issues with labs and chain of custody/cross contamination I think.

Also, just an FYI, check out Manna poultry protector as it will save you a lot of money over nukem!


Very good point!

A 2nd opinion is the best start.


actually i’ve had 2 different labs run product over the last 2 months and both have shown same result.

i’m out of ideas. i suppose it’s possible someone is coming in at night and spraying something but highly unlikely. i have cameras and all but yeah, no, that’s not what’s going on.

at this point i don’t even know what to do anymore to further the investigation.

and thanks for the heads up on Manna!


Perhaps sending in samples of the products you use so the lab can isolate which one is causing the problem?


I have talked with people in the past about PB residue and they were bombing empty rooms between batches. They had similar test results, passing but not well enough to extract. The drift was getting into the drying rooms through the HVAC system. For it to be 400ppb, the source has to be close.


My advice is to test several times during the grow cycle. But use one lab for testing cycle. This will identify when the specific failed pesticide is showing. Using one lab ensures that the instrument calibration is the same. The reason folks getting different results from different labs is because of instrument calibrations.


appreciate the input.

i’ve not bombed a room here in well over a year. both labs are testing the same. i’ll call the lab and see if they can do some tests throughout the life of a few plants and see what we come up with.



Its a stretch, but are there chrysanthemums growing around you? Its highly unlikely that bits and pieces are getting the product your product, but you never know. Also there might be drift of pyrethrins being sprayed where the trim and smalls are getting processed. Its not always where the grow is, could be where its processed.


not to my knowledge and no chance of any use of pyrethrins onsite. only thing i could think is if there is a hemp farm close i don’t know about. i know that glyphosate can travel quite far on wind.


If drift at 100ft equals 100%, then drift at 200ft equals 20%, drift at 400ft equals 4%, at 800ft 0.8% (20% of each doubling of distance of the previous number). If spraying isn’t happening within about a quarter mile, it isn’t drift. The amount of PB dift at 800 ft would have to be 50 ppm at 100ft (an unholy number) and would have to inundate your crop to cause 400ppb residue.

Most farmers and pesticide applicators know the proper conditions to spray. If the conditions favor drift it is a waste of money to spray, some 50% will be lost, and usually, but not always, they will not waste money when farming operations are based on margins.

From some scientific paper on the subject:

Following a 6lb per acre application (a normal dose is 0.5lbs per acre).

“PBO initial residues detected in soil samples were low (0.84 microgram/g soil [0.84ppm]) while no residues of PBO were detected in runoff water.”

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interesting info


Where are you getting your clones?