Using Visikol® for Plant Biology™ in the Identification of Powdery Mildew and Botrytis in Cannabis

Legal medicinal and recreational Cannabis has become a booming industry in the past decade and a new frontier in the intersection of botany and pharmacology. People with a range of medical conditions are finding Cannabis to be a safe and reliable alternative to many of the traditional drugs of the pharmaceutical industry. However, in becoming a more mainstream medicinal product, a major hurdle the budding Cannabis industry faces is quality control. Issues have been raised about high levels of fungal contamination detected in both indoor and outdoor grown Cannabis. While nothing new to many agricultural sectors, pathogens like Powdery Mildew and Botrytis are becoming a major threat to the adoption of Cannabis as a legitimate therapy, especially for patients with compromised immune systems. The first step in stopping a plant pathogen is correct identification, and Visikol for Plant Biology has been shown to be a simple, rapid, and dependable tool in fighting fungal disease.

Powdery mildew is a geographically widespread pathogen with a broad host pool. The key identifier is a thin white hyphal mat that forms primarily on the underside, but sometimes on the tops of leaves. If unaddressed, this mat will become progressively denser and cause necrosis of leaves, weakening and ultimately killing its host. Botrytis, commonly known as grey mold, is another major pathogen of Cannabis and has a similar geographic range and macro appearance as powdery mildew. The problem with relying simply on the white hyphal mat as an identifier is this is also symptomatic of downey mildew, white mold, some rusts, and many other fungal pathogens. Another issue faced is the disease life cycle, the earlier you catch the infection the higher the likelihood of salvaging material, but the more difficult it becomes to positively identify the pathogen. In both cases the fungal pathogen works its way into the dense flowers of Cannabis where even if seemingly treated, spores can remain and leave the final Cannabis product contaminated and unfit for sale. Microscopic analysis has much greater identifying power then the naked eye in determining what disease a grower is facing and when dealing with dense hyphal mats, clearing reagents like Visikol for Plant Biology can greatly help avoid false positives and false negatives.

Under the microscope Botrytis is a dead give-away, its conida (asexual spores) look exactly like a bunch of grapes on a vine. Powdery mildew does not have such a clear morphological structure, but staining with Meltzer’s reagent (Hertwig’s solution substituted with Visikol for Plant Biology) will cause a positive amyloid reaction, turning the cells a bluish brown color. In this way, an amateur microscopist can confidently identify the pathogen threat and take appropriate chemical or organic measures to stem the disease progression. The simple addition of Visikol for Plant Biology into the IPM workflow of a Cannabis producer can make the difference between saving a high value harvest or facing contamination which can not only make the product unfit for sale, but if repeatedly submitted to regulators, could cause a growers license to be revoked.


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