Having a batch fail for Aspergillus does not mean that you did anything wrong when growing your cannabis. Aspergillus and humans share the same environment, so it is very likely that you interact with and even breath aspergillus spores every day. If you are growing outside, then preventing aspergillus can be nearly impossible and based mostly on luck. Although it is most commonly found on dead leaves, compost and other decaying vegetation outdoors, it can be easily brought indoors on shoes, clothes or bags. Due to its rapid growth, it can be hard to combat once it has infested an area. Thoroughly cleaning drying rooms and trimming stations with an alcohol or bleach solution between batches is a great way to keep aspergillus at bay. Pasteurizing or decontaminating your product prior to testing is a very effective way to not only ensure that you will pass your compliance test, but it will also effectively kill off any additional microbials that may have already started breaking your cannabis down and turning it brown. Effectively extending the shelf-life of your product.