Downy Mildew: Caused by Pseudoperonospora cannabina, this
disease presents as water–soaked spots that start as yellow–green, progress to bright yellow, and become angular and vein–delimited. Gray to black “downy” sporulation develops on the undersides of
leaves. Downy mildew thrives in cool, wet conditions with relative humidity above 85%. The host range is limited to Cannabis sativa. Spore movement occurs locally through splashing water or contaminated tools, while long–distance spread typically results from the movement of infected plant material.
