Tag: powdery mildew

First report of the powdery mildew pathogen of hops, Podosphaeria macularis, naturally infecting cannabis (Cannabis sativa L., marijuana) plants under field conditions.

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!