Manage speed to eliminate spray drift

Author: | Date: 01 Aug 2012

Cover page of Practical Tips for Spraying (Fact Sheet) - reprinted August 2013

Research shows that the risk of spray drift increases substantially when spray equipment travels fast during higher wind speeds.


A Canadian study showed that, during higher wind speeds of about 20 kilometres per hour, machinery travelling at about 30km/h almost doubled the amount of chemical contributing to spray drift risk, compared with machinery travel speeds of 8km/h.


The same study revealed that spray drift risk was not affected by travel speed during slower wind speeds of 7 to 8km/h (under daytime conditions).


Spray operators are therefore advised to avoid travel speeds above 16 to 18km/h during higher wind speeds unless there is excellent boom height control and equipment is set up to minimise airborne droplets by providing spray quality which is coarse or larger.


This is some of the information outlined in the new Practical Tips for Spraying Fact Sheet, included in the July-August edition of the Grains Research and Development Corporation (GRDC) magazine Ground Cover and available at


The fact sheet, developed by the GRDC in conjunction with Bill Gordon, of Bill Gordon Consulting, contains advice to reduce spray drift including:


  • Make the most of favourable weather conditions, especially wind speed;
  • Avoid spraying during surface temperature inversion conditions;
  • Use the coarsest spray quality that will provide efficacy;
  • Maintain boom height to achieve double overlap, but no higher;
  • Try to minimise your travel speed;
  • Utilise unsprayed areas and downwind vegetative buffers.







GRDC Project Code: BGC00001


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