A GRDC survey tracked herbicide resistance in central West NSW crops. Glyphosate-resistant annual ryegrass jumped from 6% in 2013 to 57% in 2014. Growers need to map resistance on their farms and mix chemical and non-chemical control.
Questions this video answers
Glyphosate-resistant samples rose from 6% in 2013 to 57% in 2014.
About 78–79 samples (speaker: "78 or 79 samples of ryegrass").
No — none of the 2013 ryegrass samples were susceptible to all products tested (speaker: "Not one of those samples... were susceptible to all the products we tested").
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Herbicide resistance is here and it's bad. That's the confronting message to grain growers from Moray Street. The chief executive officer of the GRDC funded Grain Arana Alliance. The Dubbo based agronomist says two years of survey data shows herbicide resistance is increasing at an alarming rate across the central West New South Wales cropping belt and growers need to change tactics urgently to develop effective long term wind management strategies.
The results that came out of that looked honestly are probably quite damning. So 2013 was the first year that we did it. Thinking back to some of those results, probably one of the key things that came out of it, I think there was 78 or 79 samples of ryegrass went into it. Not one of those samples came into that survey were susceptible to all the products we tested. So 100% of the ryegrass samples came in with were resistant. Then when you had a look at it and strip that down, we tested a wide range of products from a lot of different herbicide groups and subgroups. And when you actually had a look at the level of cross resistance between groups, resistance to multiple modes of action was quite bad. So the majority of them were resistant to four or more herbicides. Looking forward to the 2014 survey, that bad story just got worse.
Critically, he says the data identifies a sharp rise in the number of glyphosate resistant samples tested from 6% in 2013 to 57% in 2014. The surveys conducted by Goa were designed to quantify the extent and type of resistance in problem weeds like annual ryegrass and wild or black oats and revealed multiple resistance in the vast majority of samples.
Personally, I think herbicide resistance is probably going to be one of our greatest issues facing sustainability of our current farming system going forward. So that's important enough to promote guys to act because it's not going to go away. If we continue to farm and continue to use herbicides, herbicide resistance is inevitable.
Mr. Street says the loss of effectiveness in glyphosate in particular could seriously challenge the sustainability of the region's profitable cropping systems.
Glyphosate absolutely central to our current farming system as a knockdown herbicide for summer fallow management, stuff like that. Now, of the samples that came in in 2014, harvest something like 60% or 2/3 of the 3/5 of the sample that came. Samples that came in showed resistance to glyphosate. That's a huge number. I don't think anybody doubted that we had glyphosate resistance, but to see such a high level in there is really concerning in that ryegrass.
Mr. Street stresses that northern growers will now have to incorporate both chemical and non chemical control options in their weed management programs.
I think one of the first things that growers have got to do is know their enemy. So it's important if you see any survivors in your crop at harvest, to go out and sample them and get them set away for herbicide resistance.
Mapping the resistance status of individual farms and paddocks is a critical first step in developing effective long term strategies for the management of hard to kill weeds.
We really need to be thinking outside that herbicide tin and thinking of other options. So certainly look, there's quite a long list. There's the harvest weed seed management tool, things like windrow burning, chaff carts, and the Harrington seed destructor, which just simply target those weed seeds at harvest and sterilize them so they're not there to compete the following year. I think unfortunately we may not see a revolution like herbicides ever again. You know, the bringing, you know, the discovery of them and the development of herbicides was just fantastic. You could put a product in a tank, go out, spray it on a paddock, relatively easy, relatively cheap, and no weeds, job's done, move on. I think the potential of seeing that in the future or another discovery like that is not impossible. But I wouldn't like to think that we can wait around waiting for that to happen. They may be, dare I say, once in a lifetime type discovery. So what we've got to do going forward is look for more those smaller incremental changes and it's just tweaking the system. And if we add a lot of little things together, we get big results and big changes.
