CEREAL, pulse and oilseed growers are being reminded to adhere to label directions for herbicides used as a desiccant and understand their target market requirements this harvest to avoid issues with chemical residues.

It is critical growers are aware that maximum residue limits (MRLs) in Australia could differ from MRLs in international grain markets such as the European Union, according to Grains Research and Development Corporation (GRDC) manager chemical regulation, Gordon Cumming.

Gordon Cumming

“Late season rain has created harvest issues across areas of Australia, and growers are now carefully considering their options when it comes to managing their crop and maximising yield, weed control and grain quality to achieve the best profit margins,” Mr Cumming said.

“However, where chemical desiccants – used to speed up the crop ripening process – are being considered there is the potential for chemical residues to arise that may exceed certain market requirements, even when used in accordance with the label directions.

“For example, for durum, the Australian MRL for diquat is 2 milligrams/kilogram, whereas in a major potential market for Australian durum, the European Union, there is a significantly lower MRL of 0.02mg/kg.”

Mr Cumming said differences in regulations made grain exporters wary and many were reluctant to consider buying grain from crops treated with certain chemicals, such as diquat on durum.

“Before using a crop desiccant, growers are strongly encouraged to speak to their marketer to understand what is acceptable for grain being sold into specific markets,” he said.

Market limits

National Working Party on Grain Protection (NWPGP) chair, Gerard McMullen, said all markets had strict limits for chemical residues and growers and marketers needed to work together to ensure grain was compliant with market requirements.

“Marketers need to closely monitor market requirements and provide advice to growers. Non-compliance can lead to the rejection of shipments in export markets and create ongoing market access issues,” Mr McMullen said.

“All stakeholders have a role to play to ensure the continued good reputation of the Australian grains industry in meeting export market MRLs.

“Growers have a legal obligation to follow label directions and understand the needs of their buyers.

“Exporters also have a role to play. Grain should not be exported unless the residue status is known and complies with market requirements.”

Three key points:

• Growers need to follow label directions stipulating crop type, rate and withholding period when using herbicide desiccants such as diquat, glyphosate, paraquat and saflufenacil prior to harvest.
• Even when complying with Australian label directions, use of a desiccant may lead to the presence of chemical residues in excess of some market requirements.
• Growers need to liaise with their marketers to determine if there are restrictions or concerns about using a particular chemical for a particular crop type.

Source: GRDC

More information: https://grdc.com.au/resources-and-publications/all-publications/factsheets/2020/preharvest-herbicide-use-fact-sheet