2,4-D is used to control broadleaf weeds. Some formulations of 2,4-D can become vapour and drift off-target, which can damage highly sensitive crops such as:
grape vines
vegetables
glasshouse crops
poppies
In some cases, crops have been damaged by spray applied up to 10 km away.
Crops are most at risk during the growing season. Vapour drift is more likely when:
2,4-D drift can occur at any time of the year.
More information on spray drift and inversion layers is available from the Grains Research and Development Corporation (GRDC) website. In Tasmania, users must apply for a 2,4-D permit between 15 September and 15 April. This seasonal control aims to lower drift risk when crops are most vulnerable.
How to Recognise a Temperature Inversion
Avoid spraying if you notice any of the following signs:
Large differences between daytime and nighttime temperatures
Calm, clear conditions when the sun is low
Wind speeds consistently below 11 km/h in the evening or overnight
Clear skies, low humidity and high-pressure systems
Dew or frost indicating cool air trapped at ground level
Smoke or dust hanging in the air or drifting sideways
Odours travelling unusually long distances
Daytime cumulus clouds collapsing in the evening
Overnight cloud cover of 25% or less
These conditions significantly increase the risk of spray or vapour drift over long distances.
Applying for a permit
Before a permit is issued, several factors may be assessed:
the distance between the target area and susceptible crops
application method (boom spray, spot spray, wiper application)
availability of alternative herbicides or weed control methods
Whether the application could have been carried out before 15 September
Some cases may require a site inspection. Inspection fees may apply.
Application Form - 2,4-D Agricultural Spraying Permit (PDF 32Kb)
2018 Label Suspension and New Instructions
On 3 October 2018, the Australian Pesticides and Veterinary Medicines Authority (APVMA) suspended all existing 2,4 D labels and issued new mandatory instructions.
Users of 2,4-D must comply with the new label instructions even if using 2,4-D with the old label. The new instructions are provided with each container at the point of retail sale but can also be found in the special gazette on the APVMA website.
Mandatory 2,4-D Instructions
Users must comply with the mandatory requirements:
do not spray during a temperature inversion
observe downwind no spray zones for aquatic and terrestrial sensitive vegetation (including sensitive crops, gardens, landscaping vegetation, protected native vegetation or protected animal habitat)
use nozzles producing droplets no smaller than the Very Coarse spray quality category
maintain detailed spray records (additional to those required under the Agricultural and Veterinary Chemicals (Control of Use) Act 1995)
advisory statements about spray application over summer