The APVMA approved the late season, pre-harvest glyphosate application late last week, which is effective immediately.

WA Farmers Grains Section President Duncan Young said it was a sensible decision that would ensure growers have the appropriate regulations to support on-farm activities.

"Now that growers are able to use the registered glyphosate product on their feed barley crop, we look forward to seeing more research work undertaken for permanent label registration and for future additions to the label registrations."

The APVMA permit lasts until 31 July 2019 and its purpose is to support wider access to late season use of glyphosate, building on a recently expired permit. The new permit only applies for use on feed barley and does not support use on malting barley crops.

Grain Producers Australia chairman Andrew Weidemann said the response from the APVMA was a good example of sensible, science-based decision-making and the speed with which the matter had been considered would be of great benefit to grain producers ahead of harvest.

"Weed control is a serious issue for Australian grain growers, with herbicide resistance reducing the available options - the very best time to stop weeds is before they get started, so spray topping late season weeds, particularly ryegrass, before they set seed is a major benefit for subsequent crops," he said.

"We simply have to have the right tools available for this job in barley and that means glyphosate, which is already registered for crop topping in Australia on various pulses, canola, wheat and sorghum.

"It is also registered for barley in the EU and North America, so the practice is well established."

For eastern states growers, GrainCorp storage facilities will not be accepting glyphosate-treated barley into any malting, hindmarsh or compass barley segregations.

Grain treated with glyphosate will be stored within common Feed grade segregations only and will not be segregated separately.