A three-way oilseed rape herbicide could prove important for poppy control in the absence of trifluralin. Mike Abram reports.

Another year, another new oilseed rape herbicide from BASF. In fact this year there are two – Shadow, containing three active ingredients, dimethenamid-p, metazachlor and quinmerac, and Nimbus, a mixture of metazachlor and clomazone.

They join a raft of other products, all based around various combinations of the three active ingredients in Shadow. Shadow itself should be seen as either “Super Katamaran or Springbok“, according to Lisa Harlow of BASF.

Consistency

The combination of the three active ingredients gives activity on the shoot, hypocotyl and roots of weeds, and brings more consistency in performance, she explains.

Part of that is down to dimethenamid-p’s ability to bind to soil particles quickly, which means it stays in the rooting zone for longer. That helps the product’s biological performance, but also means it is safer for the crop, she says.

Its main benefit over Katamaran, which is being withdrawn from sale, is better control of key broadleaved weeds, poppy, cranesbill and shepherd’s purse.

All three, but particularly cranesbill and shepherd’s purse, are key strengths of dimethenamid-p. Springbok, a mixture of dimethenamid-p and metazachlor, is also good on poppies, Ms Harlow says. “But where you’ve got high populations or a longer germination period we’ve found Shadow to be more consistent – quinmerac helps with poppy control.”

Split application

A split application of 1.5 litres/hapre-emergence and 1.0 litres/ha early post-emergence of Shadow has given the best results against poppy, helping to prolong persistence. Even so, she warns, it might not give complete control.

“It will be the best product on the market [following the withdrawal of trifluralin] but if there is a long germination period, poppy control might not be 100%. We could see a few more red fields in the future.”

Bryce Rham, an independent AICC agronomist based in Shropshire, says he will be using Shadow on land with a combined poppy and cranesbill problem. “If it is primarily cranesbill I will use Springbok. On light land with poppy, speedwells and pansy, Novall is a good choice.

“For general broadleaved weeds Butisan plus Treflan is a relatively cheap option.”

The loss of trifluralin will inevitably mean more expensive weed control in oilseed rape, he adds. “It means we will end up having to use full rates [of other options]. Trifluralin allowed you to cut rates and still control poppies.”

The second new BASF product for the autumn is Nimbus, a mix of metazachlor and clomazone. Clomazone’s strength is cleavers, Mr Rham says. “It can make the crop go white, but it does grow away.”

It is strictly pre-emergence, Dave Ellerton of ProCam, warns. “In a cleavers situation it is even better than Shadow it is also good on hedge mustard.”