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  • Writer's pictureDr. Dan Jin

Cannabis Strains with Wide Leaflets are Less Resistance to Fungal Infection

Updated: Dec 8, 2023

A recent cannabis phenotyping study conducted by scientists in PBG BioPharma showed that cannabis strains with wide leaflets are less resistant to Botrytis cinerea, a pathogen which causes gray mold in the inflorescences.

Narrow-leaflets landraces originated from regions with relatively humid conditions (Colombia, India, Jamaica, Thailand, etc.) and evolved natural resistance to fungal infection, whereas wide-leaflets landraces adapted to arid the Afghani environment in which fungal resistance was unnecessary. More THC dominant varieties with wide leaflets had Botrytis cinerea infection than in CBD dominant and intermediate strains with narrow leaflets, indicating that these strains face additional risk in a greenhouse environment. Alternatively, this may reflect the current market in Canada – growers and users favour large and compact inflorescences, which are a trait of wide-leaflet strains.


  1. Clarke, R. C. & Merlin, M. D. Cannabis domestication, breeding history, present-day genetic diversity, and future prospects. Critical Reviews in Plant Sciences 35, 293–327 (2016).

  2. McPartland, J. M. McPartland: A review of Cannabis diseases. Journal of the International Hemp Association 3(1): 19-23 (1996).

  3. Jin, D., Henry, P., Shan, J. & Chen, J. Identification of Phenotypic Characteristics in Three Chemotype Categories in the Genus Cannabis. HortScience 1, 1–10 (2021).

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