Changes to 2,4-D label instructions are being highlighted ahead of potentially large summer weed control programs resulting from a wetter-than-normal spring and summer.

GRDC chemical regulation manager Gordon Cumming has been speaking at GRDC Spray Days, reminding growers that the Australian Pesticides and Veterinary Medicines Authority (APVMA) finalised the review of all 2,4-D labels in September 2020. This resulted in several amendments and changes to all labels relating to the herbicide’s use conditions.

APVMA’s review followed the 2,4-D Environmental Assessment Report in 2018. That report aimed to ensure all products containing 2,4-D continued to be used in a manner that was safe for the environment and agriculture.

The new instructions for use include:

• a mandatory requirement to use nozzles producing droplets no smaller than very coarse spray quality;
• an advisory statement about spray application over summer to use extremely coarse (XC) to ultra-coarse (UC) spray quality in sensitive areas;
• DO NOT spray when hazardous surface temperature inversion conditions exist;
• DO NOT apply if heavy rains or storms are forecast within three days, or if any rain is expected within six hours; and
• DO NOT apply in a manner that may cause an unacceptable impact to native vegetation, agricultural crops, landscaped gardens and aquaculture production, or cause contamination of plant or livestock commodities, outside the application site from spray drift.

More-detailed buffer zones are now provided on the label for boomsprays, optical spot spraying technology and aircraft, taking into account application rate and release height.

Mr Cumming says the buffer zones provided on the labels give guidance and indicate the minimum required distance.

“These distances are calculated on worst-case scenarios for both native vegetation and natural aquatic areas, and may not be sufficient in all instances. For example, the presence of sensitive crops beyond the stated buffer zone may still pose a risk from spray drift when they are downwind of the point of release. Whenever possible, the application should be made when the wind direction is blowing away from any sensitive crops or vegetation.”

More information: GRDC’s Spray Drift resource hub.