Zamir K Punja
Published: 22 Sept 2021
DOI: https://doi.org/10.1080/07060661.2021.1960424
Question Investigated: Is there more than one species of powdery mildew that infects cannabis, and is there cross infectivity between different crops such as hops?
Plants Used: Chronic Rider, outdoor grow in Fraser, BC
Picture shows the difference in appearance between two species of PM causing fungi infecting cannabis.
Main Takeaways:
– Different species of fungi can cause powdery mildew in cannabis.
– A common species of PM affecting cannabis in greenhouses is Golovinomyces ambrosiae.
– Hops PM species is Podosphaeria macularis
– Different species of fungi will result in slightly different appearances of powdery mildew on cannabis leaves.
– Though usually crop-specific, related crops can sometimes be affected by the same species of fungi that cause powdery mildew, such as in this case where PM from hops jumped over to cannabis.
– With different fungal species, we may see that different fungicides have slightly different efficacies.
– Monitor environmental conditions and keep track of which sprays are working or not working for your crops in your area. Scout, treat, record!
In the Garden 