Detection of off-target herbicide deposition

The issue​

closeup of cotton leaf with curled margins due to herbicide damageHerbicide movement in air; by spray drift, movement with dust, or by volatilisation and redeposition, can potentially cause injury to non-target crops and native vegetation kilometres away from the site of application. Recent summer growing seasons have seen repeated herbicide-related injury to cotton crops, resulting in estimated economic losses of $10-$30 million dollars. Despite desktop modelling studies showing the potential for damage and numerous reports of herbicide injury non-target crops, actual measurement of off-site herbicide deposition in Australia is scarce. ​


  1. To provide baseline information about  the aerial movement and  deposition of group M (e.g. glyphosate) and group I (e.g. 2,4-D) herbicides in the Macquarie Valley during summer when cotton injury has been previously documented;​
  2. To assess the sampling efficiency, cost effectiveness and suitability of three different methods for  measuring  aerial herbicide deposition and​
  3. To determine primary routes of transport and periods of higher relative hazard so recommendations can be made for practice change and ongoing monitoring​

"Filed with tractor and spray rig applying herbicide

What we are doing​

  1. Weekly aerial deposition samples have been taken from 6 sites in the Macquarie Valley from Dec 2019-Mar 2020.​
  2. Measuring the load of 2,4-D and glyphosate being deposited per hectare​
  3. Deposition can be related to toxicological thresholds (e.g. deposition rate at which growth of non-target plants is affected) ​

Outputs and/or outcome​

  • Primary routes of transport (e.g. spray drift or deposition in dust or rain) and periods of higher relative hazard to non-target plants identified. ​
  • Information used to formulate specific recommendations for practice change and ongoing monitoring to manage risk. ​
  • Trust and cooperation between the regulator (EPA) and industry improved whilst herbicide use for sustainable agricultural production maintained​

monitoring equipment to collect airborne herbicide

Partners (or collaborators)​


NSW DPI Livestock systems


Mick Rose​

Wollongbar Primary Industries Institute​