The Agricultural Research Council (ARC) has embarked on a detailed disease prevention study for cannabis and hemp. Fact-finding missions in Limpopo and Gauteng identified a number of threats faced by cannabis farmers and ARC is analysing the collected data to begin developing crop health strategies.

Dr Elsie Cruywagen and Dr Juanita Engelbrecht write in ARC’s latest newsletter # 20 that with the “burgeoning interest in cannabis cultivation for both industrial and medicinal purposes, safeguarding crop health is very important”.

“By understanding the dynamics of pest and disease pressure, growers can implement targeted management strategies to mitigate risks and ensure the sustainability and profitability of their operations”.

“Moreover, this research underscores the critical need for ongoing investment in cannabis crop protection. As the industry continues to evolve, so too must our understanding of the challenges it faces.”

They explain that decades of heavy restrictions “have left a void in research regarding this versatile crop. Now, as regulations ease and cultivation expand, new challenges are emerging, particularly in the realm of pest and disease management when the crop is grown in monoculture.”

With funding from the Department of Agriculture on integrated pest management of vegetables, industrial and medicinal plants, ARC began “a survey and the identification of pests and diseases affecting cannabis cultivation in South Africa”.  

ARC conducted field trips in Limpopo and Gauteng to get an insight into disease progression throughout the growing season, typically for the period from December to March.

During the past two years ARC researchers observed disease syptoms and collected samples to identify the causal agents2023 – 2024, various disease symptoms were observed and samples collected for analyses in the laboratory to identify the causal agents.

Among the isolates obtained, notable fungal pathogens identified included Agrothelia rolfsii causing southern blight, Septoria spp. causing leaf blight and Golovinomyces spp. causing powdery mildew.

Damping-off was also observed and various species, including Rhizoctonia solani, Pythium and Fusarium species were consistently isolated from these samples.

Various samples with viral related symptoms were also collected and are being analysed. The most prevalent pest observed during the growing season was budworm / bollworm, which are the larval stages of various moths.

ARC is now conducting pathogenicity tests to confirm the roles of the different isolates as the causal agents for various disease symptoms.

In short, this research is essential to accurately identify and address the threats posed by these pathogens to the cannabis industry in South Africa.

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