GRAIN industry leaders are warning the industry needs to work harder to minimise occurrences of severe spray drift if it wants all forms of chemistry to remain freely available.
There have been high profile spray drift incidents in Queensland where cotton has been severely damaged by drift, believed to be caused by spraying during inversion conditions.
At present it is believed off-target 2,4-D ester, a phenoxy herbicide designed to control broadleaf weeds, is the culprit however lab tests have not confirmed this.
Cotton is extremely sensitive to 2,4-D.
Spray inversions occur when air temperature increases, rather than decreases with altitude, usually at night or early morning.
In inversion conditions spray can be lifted up in the inversion and deposited many kilometres away, with damaging impact on off-target crops.
Despite high profile education campaigns and the advent of technology designed to help predict inversion conditions, such as the Goanna Telemetry app, crop damage is still occurring, leading to questions regarding potential restrictions of the product or of application hours.
Grain grower leaders and spray drift experts said the trend towards larger farms meant some operators may be pushing too hard when it came to spraying hours.
"This is very much a small minority but unfortunately as an industry we are only as good as our lowest common denominator," said Grain Producers Australia board member and chairman of the National Working Party on Pesticide Application Andrew Weidemann.
"As farms get larger there is increasing pressure to get over more and more hectares and there is only a limited amount of time in the day," he said.
"In spite of a concerted industry campaign to highlight the risks of spraying in inversion conditions it appears some people are still taking the risk which is going to be detrimental to all if we end up with a situation where use of 2,4-D is restricted or even banned or if blanket exclusion zones are implemented."
Mary O'Brien, Mary O'Brien Rural, who specialises in spray drift management, agreed that farmers were trying to do too much spraying with too little equipment.
"At harvest if you're trying to get the crop off you'll get another contract harvester in without thinking, yet with spraying, rather than get a contractor we see farm businesses setting up split shifts and going overnight which often results in inexperienced operators going when there is the highest risk of drift," Ms O'Brien said.
"As a simple message to those doing summer spraying, if you're spraying past midnight, you're part of the problem," she said.
"It can technically be done by skilled and experienced operators in the right conditions but unless it's cloudy or there are moderate or stronger winds there is the high potential an inversion could occur any night over the summer period, so it is just not worth the risk," she said.
Ms O'Brien said 2,4-D ester, along with paraquat and glyphosate was one of the big three herbicides in Australian conditions.
"All three products are vitally important to our cropping systems and all three have their challenges, with 2,4-D it is spray drift, with glyphosate it is social licence in response to the claims it causes cancer and with paraquat it is the handling of a chemical that can be dangerous."
"We need to do everything right to retain access to these products and these big spray drift issues put pressure on 2,4-D."
Mr Weidemann said it was not just phenoxy herbicides that were drifting.
"This is not limited to the phenoxies there are other chemicals with issues with drift, but the damage caused can be extreme so we need to work hard to prevent more costly drift incidents."
"Most cotton producers also have broadacre grain operations so they are not going to want a ban on 2,4-D, they, like the rest of us, just want to see it being used right."