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New requirements for 2,4-D products

By John Fowler
Extension Agronomist 

November 2018

Landholders need to be aware that there have been some changes to the way a common broadleaf herbicide can be used in Australia.

All 2,4-D products now have stricter use requirements due to label changes that came into effect on 3 October. The changes apply to all 2,4-D herbicides, including old stocks in farm storage sheds. If you’re a landholder using any 2,4-D herbicides, you need to comply with the new requirements from now onwards.

In brief, the new requirements include:

  • a requirement to use nozzles producing droplets no smaller than ‘very coarse’
  • the product must not be sprayed when surface temperature inversion conditions exist (i.e. the air temperature increases with height from the ground).
  • updated mandatory record-keeping requirements
  • downwind mandatory ‘no spray’ zones.

Nozzles

The first thing most landholders who use 2,4-D herbicides will need to do is update the nozzles on their booms.  The majority of nozzles, including low-pressure air induction nozzles, will not produce the required droplet size.  For example, all 02 (yellow) low-pressure air-inducted nozzles operating at or above 3 bar pressure will produce medium or coarse droplets (according to the ASAE S572.1), not the ‘very coarse’ droplets that are required.

Several (but not all) of the high-pressure air-induction nozzles will produce the required droplet size. However, while the legislation requires ‘very coarse’ droplets, it also recommends a minimum of ‘extremely coarse’ (XC) between 1 October and 15 April.  The preferred nozzle is the TTI, which produces either ‘extremely coarse’ or ‘ultra coarse’ droplets, depending on the nozzle size and operating pressure. (See the GRDC Nozzle Selection Guide – July 2017)

I spoke with one landholder last season who ordered TTI nozzles for his boom.  He informed me that his was the first order that his supplier had ever received for these nozzles, which is a little concerning.

Avoid spraying when a surface temperature inversion exists

The new label requirements state that 2,4-D must not be applied if there is a surface temperature inversion. It also indicates that these conditions exist most evenings, one or two hours before sunset, and persist until one or two hours after sunrise.

Some indications that a surface temperature inversion probably exists include:

  • smoke or dust hangs in the air and moves sideways, just above the ground surface
  • wind speed is constantly less than 11 km/hr in the evening and overnight
  • cumulus clouds that have built up during the day collapse towards evening
  • distant sounds become clearer and easier to hear
  • aromas become more distinct during the evening than during the day.

This means that most spraying needs to be conducted during the daytime when vertical mixing of the air prevents inversions from developing.

Record keeping requirements

Users of 2,4-D products must make an accurate written record of the details of each spray application within 24 hours of the application and keep this record for a minimum of two years.

Details that need to be recorded include:

  • date of spraying, including start and finish times
  • specific location (property and paddocks sprayed)
  • full trade name of product(s) used
  • rate of application (hectares sprayed and rate/ha)
  • crop sprayed (i.e. crop type, pasture, fallow etc.)
  • wind speed and direction when spraying
  • temperature and relative humidity when spraying
  • nozzle brand, model, size, type and application pressure
  • height of boom above ground
  • name and contact details of person applying the herbicide.

Downwind mandatory ‘no spray’ zones

The minimum distance for downwind ‘no spray’ zones varies, depending on:

  • the 2,4-D formulation being use (e.g. IPA salt, DMA salt, monomethylamine, DEA salt, sodium salt, EHE etc.)
  • the application rate
  • the type of crop or pasture being sprayed
  • whether the downwind sensitive area is aquatic or terrestrial.

For most crops and pastures, they are in the range of 10 to 50 metres, but there are some that extend to 160 m.  Applicators need to see the relevant tables to determine the required minimum downwind ‘no spray’ zone.

Consequence of failing to apply with the new requirements

The new guidelines are mandatory for all users of 2,4-D products.  The monetary penalties for each contravention of a condition of the new permit are:

  • up to $189,000 for an individual
  • up to $315,000 for a body corporate.

I trust that no landholders will actually contravene the new requirements, so the size of the penalties is of general interest only.