The United States Department of Agriculture estimates that crop diseases cause $220 billion in crop losses every year. Cannabis is no exception. With thin margins and declining wholesale prices, cannabis growers simply can’t afford to lose crops to disease or even have them reduce yields.
Factors Contributing to Cannabis Disease
While cannabis is not inherently more susceptible to disease compared to other plants, the likelihood a plant will acquire a disease depends on a variety of factors such as environmental conditions, cultivation practices, and genetics.
Environmental Conditions
Any deviations from the optimal conditions for cannabis plants can increase their susceptibility to disease. For example, high humidity levels can create favorable conditions for fungal diseases like powdery mildew and botrytis. Similarly, poor soil drainage can leave plants susceptible to root diseases, such as Fusarium and Pythium.
Cultivation Practices
The way cannabis is grown can also influence its susceptibility to disease. For instance, overcrowding plants can restrict airflow, creating a conducive environment for fungal diseases. Overwatering or underwatering can stress the plant, weakening its natural defenses and making it more vulnerable to pathogens. Additionally, improper sanitation practices, such as using contaminated tools can spread disease throughout the cultivation environment. In fact, improperly sanitized tools are believed to be one of the main means of transmission of Hop Latent Viroid.
Genetic Factors
The genetic makeup of cannabis plants plays a significant role in their disease resistance. Some cannabis cultivars may possess natural resistance or tolerance to certain diseases, while others may be more susceptible. In fact, it’s not uncommon for cannabis growers to observe sick plants of one cultivar directly next to another cultivar that is unphased. Breeders often select for disease resistance traits when developing new cultivars to mitigate the risk of infections.
Preventing Cannabis Crop Diseases
The Ministry of Agriculture in British Columbia has recently issued a fact sheet detailing the symptoms and transmission of the most prevalent diseases impacting cannabis plants. Among these are Fusarium, Pythium, Powdery Mildew, Botrytis, and Hop Latent Viroid (HLVd). Many of these pathogens result in stunted growth, decreased yield, and potency reduction. Pythium, for instance, can even lead to plant demise.
It goes without saying that growers must take all necessary precautions to prevent infections and ensure a productive harvest. The fact sheet concludes with several recommendations for disease prevention in cannabis plants, including:
- Maintaining a hygienic grow environment.
- Regulating humidity and temperature levels..
- Treating irrigation water.
- Identifying and eliminating diseased plants promptly.
- Opting for disease-resistant cultivars.
- Using disease-free planting materials or cuttings.
