Emerging Fungal and Oomycete Diseases of Cannabis in South Africa: First Reports and Pathogenicity Confirmation

ABSTRACT The rapid expansion of cannabis production for medicinal purposes in South Africa has led to increasing concerns regarding the prevalence and impact of significant disease challenges, particularly with regard to fungal and Oomycetes pathogens. This study aimed to identify and confirm the pathogens causing wilting, yellowing and white and grey mould symptoms on cannabis. Samples were collected from an aeroponic cannabis facility. The resulting isolates were identified based on DNA sequence data from the rDNA‐ITS and tef1‐α loci, and the pathogens were confirmed as Botrytis cinerea , Fusarium oxysporum , Pythium myriotylum and Sclerotinia sclerotiorum . Pathogenicity trials further confirmed that all these species were capable of causing the observed symptoms on cannabis plants. Notably, this study represents the first report of these pathogens causing disease symptoms on cannabis in South Africa. These findings emphasise the need for proactive disease monitoring and the development of management practices, to minimise the impact of fungal pathogens on the growing cannabis industry in South Africa.