On Christmas Day farmers around Walgett in north-west New South Wales noticed their infant cotton plants had begun to wither. Leaves began to curl and die, killing some plants and stressing others.

Within days, it was clear Walgett was facing a serious incident that had affected nearly 6,000 hectares (60 sq km) of cotton farms reaching as far as Burren Junction, and Rowena.

The culprit is believed to be a giant plume of 2-4,D, a herbicide that is used to kill broadleaf weeds in fallow fields and in some cereal crops. A few days earlier it had rained, which prompts the weeds to sprout and farmers began spraying – though who is responsible for the 2-4,D plume remains a mystery.

The spray, possibly used at night, is believed to have been trapped in an inversion layer in the atmosphere and then drifted over the highly sensitive cotton plants.

But cotton might just be the agricultural equivalent of the canary in the coalmine. Jo Immig, coordinator at the National Toxics Network said the effects of herbicide drift got public attention when cotton was affected and there were financial losses, but off-target spraying was probably affecting other areas, such as bushland, national parks, waterways and population centres, without attracting the same sort of scrutiny.

“It’s not as obvious when it’s in other parts of the environment. The regulators haven’t had nearly enough concern about pesticide drift and its impacts,” she said.

“From our pespective, this is evidence that spray drift happens regularly and it explains how pesticides get into the the food chain and the waterway.”

So severe is the cotton crop damage that the town convened an urgent meeting of all farmers and agronomists on 4 January to establish its extent and map out a plan to prevent a repeat.

Severe cotton leaf damage from near Walgett in northern New South Wales. Photograph: Cotton Australia

The vice chair of the Walgett Cotton Growers’ Association, Bernie Bierhoff, says cotton crops on more than 10 farms, including his own, had been affected by the off-target spray drift – some seriously.

“Spray drift damage is a terrible blow for the affected cotton growers, who are already struggling with limited access to water for irrigation this season,” Bierhoff said.

“While it is still early days, the information we have to date suggests more than 5,000 hectares of cotton has been affected by off-target spray drift in the days leading up to December 25.”

Some cotton growers are facing complete crop loss. Others are weighing whether to remove damaged plants to conserve water.

The herbicide was also breathed in by farmers and their families and entered the waterways.



2-4,D is one of the oldest herbicides used in Australia and causes broadleaf weeds to grow uncontrollably and die, without hurting grass crops such as wheat.

But despite its long history of use since the 1940s, it remains under scrutiny. The World Health Organisation’s International Agency for Research on Cancer affirmed its classification at 2B in 2015, as “a chemical that possibly causes cancer”.

2-4,D was one of the ingredients in the defoliant, Agent Orange, though not its most toxic element.

Often herbicide instructions specify that they are not to be used above a certain temperature, say 30C, because higher temperatures cause them to become more volatile and evaporate into the atmosphere.

“Unless they were spraying at night or very early in the morning, it’s hard to believe this incident at Walgett involved spraying within the guidelines,” Immig said.

She said some newer products had much more stringent guidelines on when and how they could be used, including requirements for buffer zones, nozzle size, windspeed, temperature and bans on use when there are temperature inversions.

But older products such as 2-4,D are not subject to the same requirements. The Australian Pesticides and Veterinary Medicines Authority (AVPMA) says it is conducting a review of its policy on spray drift, but there is no indication of when it might report.

This is not the first time off-target drift has decimated cotton crops, but the problem may be getting worse as climate change drives up temperatures.



In January 2016 a similar phenomenon wiped out 60,000 hectares of cotton near Walgett, resulting in 20% of the crop dying and losses estimated at $20m.

In February 2017 30,000 hectares of cotton was damaged around Griffith in NSW.

Bierhoff says farmers in the Walgett area have now agreed to refrain from night spraying of 2-4,D – when inversion layer effects are more likely to occur – and to voluntarily refrain from using the herbicide between October and February. Other more expensive options will be used in that period.

None of the regulators had been up to investigate, he says.

APVMA also says it has 2,4,D under review and will report by April, though the review has been running for nearly 15 years. The highly volatile ester version of 2-4,D was banned in 2006 in Australia, 20 years after it was withdrawn in Europe.

In the meantime, APVMA is going through an unprecedented upheaval as a result of the federal government’s decision to move it to Armidale in National party leader Barnaby Joyce’s electorate.

Senate estimates committees have been told the agency has struggled to convince staff to move to Armidale, with the result that almost half the agency’s scientists had left and 20% of jobs were vacant at the end of 2017.

A report by consultants Pegasus Economics recommended the agency recruit staff from overseas and consider e-working arrangements in order to keep running.



