Although all farmers are very familiar with the principles of crop and chemical rotation, not everybody makes changes as often they should.
Unfortunately, logic dictates that it’s the crops and products they most value that growers are most likely to put at risk.
It goes without saying that there’s no herbicide that’s currently more highly prized than Sakura, which helped create such high expectations from – and reliance on – the pre-emergence application window. When a single product has made such a difference to the viability of cropping, and there’s so much potential profit at stake, growers are understandably reluctant to move away from it.
The problem is that there is an even more powerful logic to the development of resistance. Repeated use of the same herbicide mode of action accelerates the development of mutated weed biotypes that it can’t control.
In short, the more people rely on a product in the short-term, the sooner it will become unreliable. The latest data on the CropLife website shows resistance to Group 15 mode of action, which includes Sakura and Boxer Gold, has already been confirmed at over 100 sites in Australia.
BASF have now come up with a circuit-breaking ‘mini-rotation’ strategy that should reduce the pressure all round, as the company’s Portfolio Manager Cereals Roger States explains.
“The introduction of Group 15 (then called Group J & K) chemistry really turned things around for a lot of growers who were struggling to manage big populations of resistant annual ryegrass,” he says. “It took a few years for some growers to make the switch, but now those products – and Sakura especially – are mainstays of most programs.
“We’ve come up with the ‘30 on 30’ strategy to cut down the lag between the release of important new chemistry and its widespread use, and to slow the development of resistance to Group 15 and other, older products. This is particularly important because of the cross-resistance risk between herbicides in Groups 3, 13 and 15 that has been described in recent scientific publications by prominent researchers like Steve Powles, Roberto Busi and David Brunton*.
“The plan is simply for growers to use the unique Group 30 chemistry of Luximax® on 30% of their wheat crop as an extra ‘mini rotation’ within the standard program.
“That ‘30 on 30’ initiative will help growers ease into using the newer chemistry with the reassurance that they’ll be able to go on using other older alternatives more widely and effectively for longer. We’ve got to protect what we’ve got.
Roger says that both replicated trial results and commercial use have repeatedly confirmed that Luximax can match the high level of weed control growers expect from Sakura. It has similar tank-mix compatibilities too, so the ‘30 on 30’ scheme can be used very flexibly.
“Over the course of a few seasons, the weed seedbank in each paddock will be exposed to an entirely new mode of action.”
“Luximax is very effective as a standalone treatment,” Roger explains, “but of course it would very seldom be applied that way. The premium grassweed pre-ems are generally applied in tank-mixes with multiple extra products. All the most likely mix partners like glyphosate, paraquat, trifluralin, triallate, prosulfocarb, carfentrazone and metsulfuron are on the Luximax label.
“Our early trial work highlighted Luximax and prosulfocarb (Arcade) as a particularly effective combination. Now we have an even better recommendation because since then we’ve launched Voraxor®, which can do several jobs at once. Growers who haven’t already tried Voraxor could take the ‘mini-rotation’ concept one step further and use it as part of their ‘30 on 30’ applications. Voraxor can play the same role as trifluralin in spiking the superior grassweed herbicides’ control of annual ryegrass, but with the massive added benefit of extended residual pre-emergent control of key broadleaf weeds.
“Adding both Luximax and Voraxor to the mix is all part of spreading the load to maintain the highest standards of control while also protecting the chemistry our broadacre cropping has become so reliant on. That’s what ’30 on 30’ is all about.”
You can get more information by visiting crop-solutions.basf.com.au or by contacting your local supplier.
Busi R. & Powles S.B. (2013). Cross-resistance to prosulfocarb and triallate in pyroxasulfone-resistant Lolium rigidum. Pest Manag Sci
Busi R. & Powles S.B. (2016). Crioss-resistance to prosulfocarb + S-metolachlor and pyroxasulfone selected by either herbicide in Lolium rigidum. Pest Manag Sci; 72: 1664-1672
Brunton DJ, Boutsalis P, Gill G, and Preston C (2018) Resistance to Multiple PRE Herbicides in a Field-evolved Rigid Ryegrass (Lolium rigidum) Population. Weed Sci 66:581–585.
Brunton DJ, Gill G, Preston C (2021). Resistance to bixlozone and clomazone in cross-resistant rigid ryegrass (Lolium rigidum) populations from southern Australia. Weed Sci.