Weather essentials for pesticide application

For pesticide application - Grower edition

Weather essentials for pesticide application aims to help those applying pesticides to understand, observe, interpret and react appropriately to changing weather conditions to ensure efficient and effective pest control while mitigating drift.

This publication provides a practical and visual guide to all weather conditions impacting pesticide applications. It places emphasis on atmospheric stability, local wind flows, turbulence, evaporation of droplets, volatilisation and dispersion, which together determine the fate of pesticides in the atmosphere and downwind concentrations impacting recipients.

Drift is invisible and yet it continues to cause millions of dollars of damage to crops and products each year. Much of the damage has been attributed to spraying during hazardous inversions, rather than spraying in conditions that are too hot or too windy.

Hazardous inversions have only recently been defined and methods to detect and forecast them specified (Grace and Tepper 2021). Some conditions of hazardous inversions described here will surprise because they go against traditionally held beliefs that inversions only occur in near-calm conditions and clear skies.