Australian Herbicide Resistance Initiative (AHRI) insight #150 - The herbicide mixture is greater than the sum of herbicides in the mix
December 1, 2020
Written by Peter Newman
“The whole is greater than the sum of its parts,”
“Just keep mixing bloody herbicides!”
Dr Roberto Busi.
AHRI researcher, Dr Roberto Busi is no philosopher, but he has recently published some significant research that shows that Aristotle knew a thing or two about herbicide resistance despite being born over 2000 years before the first herbicide. Amazing! The message from this research - never assume that a herbicide mixture will fail even if there is resistance to both components of the mix.
This research was supported by GRDC and involved cooperation between a team of agronomists and 58 farmers to sample ryegrass from 140 fields followed by extensive herbicide resistance testing. It confirms what other, smaller studies have shown in the past, that herbicide mixtures are a powerful tool against resistant weeds. For example, 34% of these ryegrass populations were developing resistance to trifluralin and 11% of them were developing resistance to Avadex®, yet when these two herbicides were combined in a mix, there was no resistance detected at all. A similar result was seen for all pre-emergent herbicide mixtures.
Spoiler alert – for all pre-emergent herbicide mixtures no populations we rated as resistant to any of the mixtures.