One of Australia's leading ecologists has warned of a biodiversity disaster if there is any move to ban the herbicide glysophate, currently under a legislative cloud overseas.
There would be increased erosion on farms, and weeds would get out of control causing the loss of habitat to native flora and fauna, a report found.
The report was compiled for the Invasive Species Council by ecologist Tim Low, well-known for his groundbreaking book on Australian birds, Where Song Began.
Mr Low said in his report he feared any move to ban glyphosate use would let invasive weeds take control of many farm and park areas.
"A ban on glyphosate would have serious environmental consequences. Weed invasions would increase in areas of native vegetation including national parks, and erosion would increase on farms," he said in the report.
Australia has baulked at matching international moves to ban glyphosate. The European Union will review the use of glyphosate in 2023, with both Germany and Austria moving already to ban the herbicide, mainly due to the chemicals allegedly damaging insect populations especially pollinating bees, rather than human cancer concerns.
The United States has seen a number of legal actions over claims that the use of glyphosate caused cancer to workers, putting it under the approval spotlight.
But Australia has held the line on banning glyphosate.
The fact the Invasive Species Council has supported the use of glyphosate is interesting considering it is often aligned with proactive environment groups, including the campaign to rid Kosciuszko National Park of brumbies.
"The widely used herbicide glyphosate has received intense international criticism, some warranted, some not," Mr Low's report said.
"Glyphosate plays a major role in the control of agricultural and environmental weeds, but its use carries health risks. It could well be a carcinogen, but if used correctly, current research suggests it is unlikely to cause cancer in humans."
Organic farming in some areas of Australia had shown that greater land was needed to produce the same yields and that for some crops such a practice was unsustainable.
"In agriculture, organic farms are chemical free, and a major shift to organic farming would see herbicide use fall. But organic farms produce less food. A South Australian study found that on two organic wheat farms, yields were 17-84 per cent lower than on conventional farms due to phosphorus limitations and weeds," the ISC report says.
"One farm at Yenda produced one sixth of the grain of a neighbouring conventional farm and 4.8 times the mass of weeds (Ryan et al. 2004). Use of mineral fertiliser was the main reason but weeds contributed. Differences in yield are typically less than this, with a review of European research finding that organic farming requires 84% more land than conventional farming. If farmers used synthetic fertilisers but avoided pesticides, the loss in productivity would be less.
"The International Agency for Research on Cancer (IARC) was conducting a hazard assessment when it determined in 2015 that glyphosate is a probable carcinogen. A hazard assessment simply asks if a substance can cause harm.
"A risk assessment asks instead if a substance can cause harm under conditions of normal exposure. Most organisations that conducted risk assessments after the IARC decision, including the Australian Pesticides and Veterinary Medicines Authority, concluded that glyphosate does not cause cancer when used according to safety instructions, and endorsed its continued use. In most of the court actions taken against the makers of glyphosate the cancer victims were repeatedly drenched, from times before the product came with clear safety instructions.
"The risks posed by glyphosate should be balanced against other risks. IARC is more certain that cancer is caused by sunshine, alcohol, salami and wood dust than it is about glyphosate. It linked glyphosate to non-Hodgkin lymphoma, but the Australian Cancer Council does not list glyphosate as one of the risk factors for this cancer.
"Australians are exposed to many chemicals that pose greater risks but escape much scrutiny. Media articles sometimes mention glyphosate traces found in our bodies as if that is especially alarming, but nearly 300 pollutants have been detected in babies, so the situation is one of many chemicals around us rather than that of glyphosate being unusually pervasive.
"But that said, glyphosate users should be careful not to inhale it or splash it on their skin. Chemical substitutes for glyphosate could be no better or worse for human health, and less effective at weed control.
"Some are harsher on the environment. One concern is 'regrettable substitutions', by which one chemical is replaced by others that seem safer only because they are newer, so less is known about their impacts. Newer chemicals could prove safer, but only time will tell.
"The surfactants incorporated into herbicides can be very harmful to aquatic life. Roundup Biactive is the glyphosate brand approved for use near water, because it has a surfactant considered safe for frogs and other aquatic life.
"Non-chemical methods of control, especially steam spraying, can be used against some very small weeds in city parks and ovals. They do not kill larger weeds in parks, nature reserves and on farms. Steam has to be used carefully because of the risk of burns, and only suits areas with vehicle access."
Meantime in Queensland, a new type of glyphosate injection gun has been invented to help kill invasive trees.
Very successful trials have been conducted on farming land near Laidley in the Lockyer Valley at a creek site near a farm that has a "forest" of celtis trees (Chinese elm). The trial found that the injection capsules of herbicide have killed celtis trees as large as 3.5m in circumference. The InJecta herbicide gun was invented by a team at the University of Queensland, and UQ's Professor Victor Galea is extremely excited by the trial results.
The team has been able to measure the right dose of herbicide to kill invasive trees. This saves on traditional methods of mixing herbicides for use and allows for good ecological practices by being able to kill declared invasive weed trees by waterways without the possibility of polluting water and water animals.
The gun drills a hole in the trunk and then inserts a herbicide capsule into the trunk. Depending on the size of the tree the capsules are inserted at spaces of bewteen 10-15cm. Each hole can be done within four seconds, cutting traditional tree poisoning times.
Professor Victor Galea said he was excited the trials had shown it was possble to kill celtis trees as large as 3.5m in trunk circumference. It may take 12 months for a large tree to die completely. The trial had shown the native trees resuming a normal canopy by the creek near Laidley after the celtis trees died.
Glyphosate is part of the herbicide mix contained in the capsules. The innovation is set to be adopted by a number of Queensland councils but has great application for farmers controlling larger invasive tree infestations such as celtis, a problem invasive tree in many areas of south-east Australia, including on the NSW North Coast.
The InJecta unit is available for sale through BioHerbicides Australia www.bioherbicides.com.au "If you check out their website you will see that there is a special on at the moment for the InJecta and two jars of Glyphosate capsules (2,000 doses). Glyphosate can be used to kill any weed tree!," Prof Galea said.
A more detailed story on the InJecta gun and operation will be printed in The Land this week.
The NSW DPI warns about celtis: "Chinese celtis is a large, invasive tree that has become an environmental weed and a potential weed of agriculture because of its ability to become structurally dominant. It rapidly colonises disturbed bushland, forms dense thickets, replaces native shrubs and trees and dominates riparian vegetation.Chinese celtis has been recognised and listed as a serious environmental weed by bush regeneration groups, Councils and the National Parks and Wildlife Service. The demonstrated ability of Chinese celtis in south-east Queensland to spread rapidly makes its control in north-eastern NSW a high priority."