Text message alert system may minimise costly spray drift damage to cotton crops

A text message warning farmers that weather conditions are not suitable for chemical spraying is just one idea being flagged to minimise costly spray drift.

While crops are thriving on recent rain in many cotton and cereal growing regions, so are weeds and to control the weeds, growers and contractors enlist the use of herbicides, often Phenoxy herbicide such as 2,4-D.

The off-target spraying of Phenoxy herbicide is estimated to be costing cotton growers millions of dollars, with Cotton Australia's chief executive Adam Kay suggesting 20 percent of this season's crop has been damaged by chemicals suspected to be coming from cereal growers nearby.

"This drift is coming from kilometres away, this is not a case where it's a neighbour spraying and you can see the drift coming on to your crop, this is drift due to temperature inversions and it's difficult to say where this is coming from," Mr Kay said.

Education, awareness and research needed

Cotton Australia is working with the New South Wales Environment Protection Authority [EPA] and Grains Research and Development Corporation to come up with ways to educate growers and spray contractors in a bid to minimise the occurrence of spray drift.

Cotton Australia regional manager for Darling Downs, Mary O'Brien, said night spraying during unsuitable weather conditions had emerged as the major cause of extensive crop damage.

"Night-time temperature inversions are very prevalent in Australia and [we need] some education of applicators to be able to identify when those inversion conditions are present," Ms O'Brien said.

"In the afternoon and late evening when the ground cools, sometimes we get that air closer to the ground cooling quite rapidly while there's warmer air above it.

"That cool air is trapped in a layer and, the issue with that is, the movement of that air.

"It tends to flow parallel to the ground so any fine droplets that are released into that inversion layer moves sideways."

Those droplets of herbicide can drift up to 70 kilometres per hour, depending on wind speed and how long the inversion conditions remain.

Ms O'Brien said research was being done on helping farmers and contractors detect inversion conditions, as well as communicating the conditions to them via an alert system.

"Cotton Australia has already had conversation with the Bureau of Meteorology in regards to what we can do it the future and how we can assist people better in determining the presence of these inversions," she said.

"There's no silver bullet to fix this problem. It's a multi-pronged approach; education, awareness, more research."

Recent cases investigated

The New South Wales Environment Protection Authority has received three recent complaints about spray drift from growers in northern NSW.

However, director of the organisation's north branch Gary Davey says there wasn't enough information to prosecute the cases reported from farmers at Mungindi, Garah, and Warren, of alleged spray drift damage to between 300 and 600 hectares of cotton.

"We investigated one and were able to identify the pesticide that was the cause of the problem, but we weren't able to identify the actual source," Mr Davey said.

"That's the problem we have with Phenoxy; having no information that we're able to follow up such as where is might have come from, when it was sprayed, and that's the difficulty we have with so many of the chemical impacts."

https://www.abc.net.au/news/2016-02-03/cotton-spray-drift-research-text/7136232