Cultivar Susceptibility to Yeast & Mold, By the Numbers

Thanks to mandatory compliance testing programs in legalized states, there is more data available on cannabis than any other crop in history. It’s an exciting time for cannabis scientists, as there is a treasure trove of vital information that can be extracted and implemented from these large datasets. 

For example, we can measure the relationship between yeast & mold levels and cultivars (or strains). 

We have data on cultivars and their results from total yeast & mold screens. There is a lot of data on this and a vital step is data cleaning and filtering. First we removed data from dishonest labs, and then filtered to only include cultivars that have been tested grown by at least three cultivators. Then we filtered the remaining data to only include cultivars tested at least 30 times.

The most common action limit for total yeast and mold is 10,000 CFU/g (colony forming units per gram). As such, we wanted to see how often each cultivar passes the 10,000 CFU/g threshold. 

Please note: cultivars are identified by the cultivator, and that growing methods & environments play a vital role in not only contamination levels but also the chemical profile of the plant. However, it is certainly interesting to observe how specific cultivars seem to be more susceptible to certain contaminants. 

Cultivars most often exceeding 10,000 CFU/g Total yeast and mold:

1. Gelato 33: 73.77% 
2. Rainbow Sherbert #11: 57.14% 
3. Bubba Kush: 43.08% 

What is it about these cultivars that makes them more susceptible to yeast & mold contamination? Is it the presence of certain compounds, like cannabinoids, terpenes, or flavonoid? Or could they be clones from popular infected mother plants? 

We can also see which cultivars have exceeded the 10,000 CFU/g least frequently and seem to be most resistant to such contamination. 

Cultivars least often exceeding 10,000 CFU/g Total yeast and mold:

1. Devil Driver: 0%
2. Mexican Flan: 0%
3. Amsd: 0%
4. Do-Si-Dos: 0%
5. Orange Soda: 0%

These are preliminary findings, and more research is needed to understand these relationships. Some regulations currently in place for cannabis prevent us from obtaining cultivar data because of prohibition against tissue culturing. Without starting with clones we know are free of fungi, it’s hard to say if cultivars are truly susceptible or if there is an infested mother plant that growers are cloning from. Stay tuned for further insights as our team continues to explore this topic.