They say that an ounce of prevention is worth a pound of cure. While cannabis cultivation may seem simple to the layman it is riddled with potential bumps in the road that could be extremely costly. Plant pathogens are just one of these bumps and they can lead to inferior product and can also greatly reduce yield and/or total crop loss if not dealt with swiftly. Early detection of such pathogens is paramount.
We’ve all seen it before – it’s that pesky white film on cannabis leaves and flowers that leaves a less than stellar bag appeal and makes for a harsher smoke with bad taste. Powdery mildew is a pain for cultivators to deal with once their grow has been afflicted and it is even harder to eradicate. Beyond being difficult to control and remove, powdery mildew is an obligate biotroph meaning that it cannot survive without taking nutrients from its host. This leads to a lackluster product with less robust trichomes resulting in lower cannabinoid and terpene production. It was initially reported by John MacPartland that the causal agent of powdery mildew was P. macularis however after numerous failed attempts by the Medicinal Genomics team to detect it using primers specific to this pathogen we decided to whole genome shotgun this pathogen. It turns out, the powdery mildew that infects cannabis is a unique species which is why the primers from the literature failed to amplify. This work revealed that its genome’s internal transcribed spacer (ITS) region sequence is 98% identical to P.macularis and Golovinomyces (the type of PM that infects grapes). This is a novel species that has been coined cannabis derived powdery mildew or CDPM which is not found on public genomic databases like NCBI therefore primers specific to this genome were developed by Medicinal Genomics.