Chemical use best practice

We encourage industry best practice when using rural chemicals.

Weather conditions for spraying chemicals

Spray agricultural chemicals under the appropriate weather conditions to minimise the movement of chemical (drift), increase efficacy and reduce costs.

Spray only when there are:

  • consistent light winds, 3 to 20 km per hour  blowing away from sensitive areas.
  • mild temperatures and high relative humidity.

Surface temperature inversions

Never spray under still or inversion conditions.

While spraying at night and in the morning is not restricted for most products, some product labels prohibit, or at least warn against, spraying when hazardous inversions are present.

During inversion conditions, damaging concentrations of agricultural chemicals can drift for many kilometres and affect sensitive corps. Refer to the Australian Pesticides and Veterinary Medicines Authority for information about surface inversions or Grain Research, Development Corporation (GRDC).

Research the weather before spraying

Before spraying check the weather in your region:

Assess the weather at application site using a weather recording device.

Keep records of your observations.

2,4-D label instructions

The Australian Pesticides and Veterinary Medicines Authority (APVMA) has spray drift instructions for 2,4-D herbicides. These instructions include requirements relating to droplet size, travel speed, boom heights, buffer distances, record keeping and inversion weather conditions targeted at reducing spray drift.

View information on the 2,4-D label requirements.

For additional technical information when applying 2,4-D product visit GRDC Maintaining efficacy with larger droplets - 2,4-D application requirements

Summer weed control code of practice

Follow the Code of Practice for Summer Weed Control to minimise off-target incidents and prevent chemical misuse.

Code of Practice for Summer Weed Control guide (PDF 449.2 KB)

Code of Practice Summer Weed Control checklist

Chemical products

  • Specific legal/regulated requirements apply to the use of Group 4 herbicides

Equipment and spray quality

  • Use nozzle types and operating pressures to produce a very coarse spray quality or larger.
  • Booms should only be 50cm above the top of weeds for a 110˚ nozzle at 50cm boom spacing.
  • Do not spray with an application speed over 18km per hour unless boom height is 50 cm or less above the target using coarse spray quality or larger and there are no inversion conditions.

Spray timing

  • Spray during the day when possible.
  • Do not spray 1½ hours before sunset till 1½ hours after sunrise, unless there is no surface temperature inversion.

Weather conditions

  • Do not spray under inversion conditions.
  • Check for inversion warnings or signs of inversions before spraying and stop spraying immediately if a surface temperature inversion or any other unsuitable conditions develop.
  • Spray when wind is blowing away from nearby susceptible plants, crops, houses and towns.
  • Spray Group 4 herbicides during the day when winds are between 3 to 20km per hour and when there is no surface temperature inversion.
  • Do not spray 2,4-D and MCPA products when there is little or no wind or variable winds.

Monitoring and record keeping

  • Monitor and record application details and weather conditions at the start and the end of spraying such as wind speed, direction, temperature, relative humidity.

Chemical use record keeping

A move towards national harmonisation of record keeping requirements means that SA chemical users might have to keep records for all agricultural chemical applications in the near future. Prepare for this regime now! Record each application of rural chemicals on your property within 24 hours and keep the records for two years.

Minimum best practice requirements

As a minimum best practice you should record all information fields shown in the record keeping form (PDF 117.4 KB or DOCX 62.9 KB) and store them electronically or as a hard copy. This includes recording:

  • date, start time and finish time of application
  • location where the application was made
  • product names and application rates
  • crop or situation and the area treated
  • spray quality or droplet size applied
  • spray pressure, nozzle brand, nozzle type, flow rate
  • weather conditions such as wind speed, wind direction, temperature, relative humidity and delta T
  • name, address and contact number for property owner
  • name, address and contact number for applicator.

Example of a completed record keeping form (PDF 102.6 KB)

Related information

Page last reviewed: 16 Nov 2023
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