Mildius

The most well-known symptom of downy mildew is the classic spot, lighter in color than the rest of the leaf, somewhat resembling an oil stain. These spots are distributed across the upper surface of the leaves, usually bordered by the veins. If you look at the underside of these infected leaves, you can see the mycelium and fruiting bodies as a whitish fuzz. These structures are responsible for the production and dispersal of new spores throughout the crop.

The affected parts eventually become necrotic and die, turning a brick-red color. Leaves deposited on the ground can carry spores, which are responsible for infections the following year.

Mildius Video

Downy mildews grow biotrophically in the intercellular space of cannabis leaves. The spores settle near the stomata before germinating, attracted by the chemicals released by these pores. Light also plays a significant role, as spore dispersal is random during periods of darkness when the stomata are closed.

It is common for the metabolic activity of the marijuana plant to increase in order to replenish the absorbed compounds.

Downy mildews require high humidity for periods of 4-8 hours and temperatures of 8-29ºC to begin infection.

Control method

The use of resistant marijuana varieties would be the most effective control.