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Microbial Testing Methods

How are your pass/fail results determined in microbial testing? I understand this is different state to state, so I was wondering if someone could share from each legal state.

In Colorado, we currently use a “total yeasts and molds” count, which has a number of inherent problems. 10,000 CFU is the pass/fail line.

We have gotten some genus tests done on failed product, which have come back as penicillium and some type of dermatophyte, both of which can be soil-born, are pretty much everywhere in the air, and don’t produce mycotoxins or human illnesses.

I would love to see Colorado take a closer look at it’s standards. From what I’ve heard, other states are testing for specific pathogens and mycotoxins, which makes more sense to in my opinion. Powdery mildew doesn’t even grow in vitro from my understanding so it goes unaccounted for. I’ve heard from a couple sources as well that 100,000 CFU would be a much more appropriate threshold than 10,000 CFU.

Share your thoughts, state guidelines, and experiences?


Here is a chart of what is required for California


Oregon is super lax. They gave up on mold testing early (PM, Bot), tho aspergillus is still part of microbials (salmonella, E.c., etc). Basically a moisture test is it. My lab told me they have never run a microbial, they only run them if the state requests it, it isn’t part of the requirements for sale. I don’t do any retail testing, I am allowed to skip it since my product goes to processing first and my process does the retail testing.


Thank you for sharing! I envy the specificity of your microbial tests… I am hoping to get some Colorado industry folks to start pushing our regulation in that same direction.


Nevada testing standards do not allow <10,000 cfu/gram of yeasts / mold (any type). Similarly moisture levels must be >15%.

Salmonella and total coliforms can’t be <1,000 cfu/gram.

There can be absolutely no detection of:
Pathogenic E. coli
Aspergillus fumigatus
Aspergillus flavus
Aspergillus terreus
Aspergillus niger

We estimate that about 40% of all tested flower in Nevada fails microbial testing. Who knows how much has been washed in solvents prior to testing to throw off the tests.