Taking shortcuts in herbicide applications can have dire consequences for Australia’s market access; a recent detection in a marketing surveillance sample of Australian barley is a serious warning for anyone considering off-label herbicide use.
From February 2014, Japan increased its surveillance protocols for all barley shipments from Australia for the next five years.
Grain samples at the laboratory for tested. The sample extraction is performed in organic solvents using ultrasonication, which enhances the transfer of target compounds into solution. The solution is then tested for a range of pesticides.
PHOTOS: Dr Joe Liu, Symbio Alliance
The detection of Group B imidazolinone herbicides in a market surveillance sample of Australian barley has brought into sharp focus the threat that unacceptable pesticide residues pose to market access.
In February this year, the Japanese Ministry of Agriculture, Forestry and Fisheries advised Australia that imazapyr and imazapic residues were detected at levels that exceeded Japanese import tolerances. The residues of imazapyr and imazapic also exceeded Australian standards.
Australia has now been put on notice, with Japan advising it will increase its surveillance protocols for all barley shipments from Australia for the next five years.
Intervix® (imazapyr/imazamox) products are the only imidazolinone herbicides registered for use on barley in Australia and should be the only imidazolinone options considered for use. These Intervix® products do not contain imazapic.
While imazapyr has a maximum residue limit (MRL) in Australia for barley (at or about 0.05 milligrams/kilogram, which means residues are not expected to be found), there is no corresponding MRL in Codex (the internationally agreed standard) or Japan.
In the absence of a barley MRL in Japan, both imazapyr and imazapic default to an acceptable detectable limit of 0.01mg/kg. Detections above this level constitute a violation.
There are no products containing the active ingredient imazapic registered for use on barley, so there is no corresponding MRL for this ingredient. Products containing imazapic are registered in Queensland and New South Wales for use at pre-sowing only and, if used according to label directions, no detectable residues are expected.
National Residue Survey
Due to the detected residue, all grain samples submitted to the National Residue Survey contract laboratory since late February 2014 have been subjected to an expanded multi-residue screen that includes all of the above-mentioned chemicals. So far, no further imizadolinone herbicides have been detected in more than 200 samples analysed.
Given the presence of imazapic in the marketing surveillance sample, the conclusion by specialists examining the case is that the chemical was used in-crop – an off-label use of the chemical.
Specialists are also worried about incorrect advice being given by advisers. A Western Australian agronomy company was recently found to be recommending on its website that barley growers use a mix of imazapyr and imazapic as a cheaper alternative to Intervix® herbicides.
Investigators say such advice is probably being given by agronomists who are unaware of the serious market consequences of such an off-label recommendation.
In some states it is an offence to provide information or advice that is likely to lead a chemical user to contaminate their produce.
The issue is likely to require even greater vigilance as more crop varieties are being released in concert with specific chemical packages, which must be used according to approved label directions.
With Australian barley exports now being more closely scrutinised, specialists say it is more important than ever that growers and advisers adhere carefully to label recommendations, understand Australian MRL requirements and those of the intended market, and check thoroughly before considering alternative products or product mixes for the purposes of cost-cutting.
Andrew Weidemann, chair of Grain Producers Australia (GPA), says the residue detection needs to be “a wake-up call for growers” to make sure everyone understands the industry has trace-back requirements from markets and that growers must responsibly manage chemical applications: “It is not worth risking the market reputation of a whole industry,” Mr Weidemann says.
Andrew Weidemann, GPA
03 5385 5089
Steven Field, Victorian Department of Environment and Primary Industries
03 5824 5532
Gerard McMullen, Grain Trade Australia
03 8300 0108
Bill Murray, National Working Party on Grain Protection
03 9763 8396
Ian Reichstein, National Residue Survey, Department of Agriculture
02 6272 5668
Note: the July–August 2014 issue of Ground Cover will include a fact sheet on Grain Marketing and Pesticide Residues
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