The ultra low volume technique requires wind speeds of 10-25 knots to provide sufficient canopy turbulence to ensure the microscopic droplets are retained in the upper tree canopy.

The voice of the timber industry since 1873
Forestry Commission Scotland has called off trials into aerial spraying of the fungicide against Dothistroma needle blight until next year, mainly because there has not been enough wind.
The ultra low volume technique requires wind speeds of 10-25 knots to provide sufficient canopy turbulence to ensure the microscopic droplets are retained in the upper tree canopy.