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Haloxyfop in canola

26/4/2022

In recent years, residue testing by the National Residue Survey has detected haloxyfop residues above the Australian Maximum Residue Limit (MRL) of 0.1 mg/kg in canola traded domestically. Verdict™ 520, Firepower®, Exert™ 520, Asset™ and Inquest® are examples of common trade names for haloxyfop.

In response to these detections, CBH has been testing for haloxyfop in canola for the past three seasons. CBH tests for chemical residues during and after harvest to help maintain Western Australia’s reputation for supplying clean and safe grain. This testing has revealed haloxyfop detections, particularly in the southern half of the grain-growing area of Western Australia. The results indicate that the use of haloxyfop in canola can result in residues in grain exceeding the Australian MRL.

The Critical Comments on the haloxyfop label state:

“DO NOT apply after the 8th leaf stage of the crop"

"DO NOT apply after the commencement of stem elongation"

"This means that application must not occur after the 8th leaf stage, or if stem elongation commences before the 8th leaf stage, application must not occur after stem elongation has commenced.”

This only allows a very narrow window for application if observing the 2-8 leaf stage guide, which can be reduced further if plants begin stem elongation before the eight leaf stage, which frequently occurs. Delays due to breakdowns, weather events and logistical complications, combined with earlier planting times, can easily result in the crop growing past the label application stage for haloxyfop. Staggered germinations from dry starts also increase the complexity of herbicide timing.

Haloxyfop was first registered in 1998 when the most common canola varieties grown in Western Australia were Karoo, Narendra and Oscar. Since 1998, canola varieties that are grown have changed dramatically with the introduction of shorter season varieties and hybrids. These advanced varieties may transition into stem elongation earlier than the traditional varieties, used for testing when haloxyfop was first registered. The varieties grown today also yield a lot higher and can have increased efficiencies in use of water and nutrients, which could result in higher levels of haloxyfop accumulated in the grain.

CBH encourages you to discuss alternatives to haloxyfop with your agronomist. There are other products that can be used to control grass weeds in canola that do not cause a residue issue. If targeting erodium, there are some canola systems with alternative methods of control. Manipulating pastures in the rotation is also a helpful way to reduce erodium numbers; haloxyfop and many other products can be applied to legume pastures.

For more information:

Canola spray compliance an industry-wide effort - GRDC


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