How to Due with Powdery Mildew of Hemp?

What is Prevent Powdery?

Powdery mildew in cannabis is characterized by white patches of powdery-looking spots on leaves, stems, and flowers. Powdery mildew infected plants may also appear stunted, and leaves appear brown. Though it rarely kills plants, heavily infected leaves can limit photosynthesis, reduce nutrient availability, and lead to leaf necrosis and defoliation. Infected flowers will also display white mycelial growth, which would be considered a lower quality product. How to prevent powdery mildew? Here are some tips:

Temperatures and Humidity

Conidia of powdery mildew can survive a wide variation of temperatures and humidity. Optimal temperature ranges for powdery mildew are believed to be between 69-84 ˚F. High humidity levels promote fungal growth, but low humidity promotes spore dispersal. Low leaf moisture is also more favorable for powdery mildew.

Genetics as a Control

Selecting cultivars that are more resistant to powdery mildew is one of the best first steps for powdery mildew control.

Nutrient Management

Nitrogen – high nitrogen has been documented to negatively affect crop resilience to powdery mildew.

Silicon – Silicon can improve plant health through increasing plant cell rigidity.

Lighting Controls

Ultraviolet B and C light (UV-B 280-320nm, UV-C 200-280 nm) has been shown to be effective in other crops at controlling the germination and spread of powdery mildew.

Water as a Control measure

Powdery mildew conidia can be damaged when immersed in water on leaves. Although this may seem like a good control measure when others are not available, it may also lead to fungal growth and possible introduction of diseases like fusarium.