Pendimethalin is better positioned within the pre-emergence treatment rather than waiting to apply it with Atlantis, according to Agrovista’s Mark Hemmant.

“Most blackgrass now has some enhanced metabolism resistance, but it has least at pre-emergence so it makes sense to use pendimethalin when you are going to get the most out of it,” he explains.

Agrovista trials at their large grassweed site at Maidwell in Northamptonshire again confirmed higher levels of control for Trooper than Liberator, he says.

In the trials the firm compared Trooper at 2.0 and 4.0 litres/ha with 0.6 litres/ha of Liberator with and without the adjuvant Grounded, all followed with an Atlantis treatment in November. At the full rates Trooper gave 96.5% control compared with 94% for Liberator. Adding Grounded to Liberator improved control to 96.5%, Mr Hemmant says.

But using 2.0 litres/ha of Trooper without any addition of trifluralin was unlikely to give enough control of blackgrass. Control dropped to 93.7% following the Atlantis application. “It’s all a numbers game. The more blackgrass you leave for Atlantis, the more you put it under pressure. So you will either need to use a higher rate or add some more pendimethalin to it.”

The firm has also trialled split applications of flufenacet using it at pre-emergence and in mix with Atlantis. “Flufenacet’s half-life is longer when the soils are cooler, so you can extend the residual period of what is the most effective residual on blackgrass by putting it on at post-emergence as well.”

The trials investigated full rate Trooper followed by Atlantis plus Firebird, applying a maximum dose of 360g/ha of flufenacet. “I wouldn’t go above that. I‘d worry about crop selectivity.” Efficacy was more consistent than Atlantis + Stomp, Mr Hemmant says.

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