23 November 2001

Herbicide hits grassweed targets hard

A GODSEND on couch, a new standard on brome and a spring top-up for blackgrass.

That is how Bayer describes its new cereal herbicide Attribut (propoxycarbazone-sodium).

Over 90% control of sterile brome has been achieved by split dose applications. But cultural control will still be needed to help keep on top of the weed, stressed the firms Andreas Amann.

Delayed drilling, ploughing deeper than 15cm (6 in), and immediate cultivation behind the combine to prevent light-induced dormancy are recommended. "It is very effective, provided the weed is not too advanced," said Mr Amann.

In German work spring application of 60g/ha of Attribut at GS10-15 of the weed gave 88% control, but at GS31-32 only 66% control was achieved.

The ALS-inhibiting herbicide is mainly root absorbed, so works best in moist conditions. Adding a tallow-amine wetter aids activity, especially in the dry. "It really helps to get the compound into the plant."

Approval in the UK is for use from Feb 1 with a maximum dose rate of 100g/ha recommended for heavy infestations of brome, preferably applied as a split, said UK technical co-ordinator Nigel Godley.

"The second application needs to be 3-4 weeks later, so any survivors recover and are actively growing when it goes on."

For light brome infestations, or a blackgrass top up, 60g/ha is recommended. Before the end of tillering is the timing for blackgrass.

On couch better in-crop control than Monitor (sulfosulfuron) is claimed and rhizome biomass and regrowth is reduced on a par with pre-harvest glyphosate treatments. "And of course those are too late for any yield benefit that year." &#42