22 March 2002

Hard-to-kill great brome meets its match in midlands

MODERN herbicide technology is helping a midlands grower overcome a previously intractable weed problem.

Great brome, more robust and harder to kill than the more common sterile brome, has plagued Robert Burdekin at Crossroads Farm, near Belper, Derbys, for nearly 20 years.

"I suspect it was present in the grass we ploughed up when milk quotas came in."

Until recently, the weed proved hard to keep in check on the 113ha (280 acre) mixed holding, causing lodging and seriously reducing cereal yields.

Minimal tillage, used mainly because the soils are so shallow, simply encouraged it.

"Our first wheats after set-aside or oilseed rape generally crop reasonably well," says Mr Burdekin. But some second wheats have been so badly infested they struggle to hit 2.5t/ha (1t/acre). Some have even been cut for silage to reduce the brome seed return.

Generally crops look fine in the autumn, but by spring the brome has often taken over, says Mr Burdekin.

Until recently, he relied on set-aside sprayed with Roundup (glyphosate) or breaks such as oilseed rape treated with Fusilade (fluazifop-P-butyl) or Laser (cycloxydim) to keep it at bay. Pre-emergence Avadex (tri-allate) followed by Fortrol (cyanazine) gave only partial control, says Masstock agronomist Nigel Francis.

Three years ago, a small trial with Monitor (sulfosulfuron) offered potential salvation. "We had a few trial packs which we used on wall-to-wall great brome," says Mr Francis.

Despite colleague Clare Bends view that Attribut (propoxycardazone-sodium) has the edge against great brome, it proved a big success, he says.

"Its never going to be 3.5t/acre land, but at least its giving us a chance to get 2.5-3t." For an outlay of about £30/ha (£12/acre) the herbicide is clearly cost-effective, he adds.

Mr Burdekins campaign against great brome now starts in autumn with three Dyna-Drive passes to encourage early chitting.

The resulting plants are sprayed-off with 0.75 litres/ha of Roundup Max (glyphosate) before mid-September cereal sowing and an appropriate autumn herbicide programme.

Monitor at 25g/ha is then applied with 0.2 litres/ha of Arma adjuvant in spring at about stem extension (GS30) of the crop. "We find the weeds at about the same stage then," says Mr Francis.

The original trial field has since been in set-aside and oilseed rape. But a clear brome dividing line still showing between the treated and untreated areas shows how successful the spring treatment was, he says.

"Last year, we treated 18 acres of late drilled wheat which received no pre or post-em autumn herbicides because of the appalling weather. The Monitor did an excellent job of holding the great brome below six inches and preventing all seed development in the ears."

The herbicide is now a key part of the spring programme wherever brome threatens, says Mr Burdekin. "Our aim is to reduce seed numbers to a manageable level and push it back into the field margins."

Pre-emergence Crystal (flufenacet + pendimethalin), used for the first time last autumn, also appears promising against great brome, he adds. "It has done a very good job and left only a couple of bad areas which may require Monitor or perhaps Attribut." &#42

BEATING GREATBROME

&#8226 Grassland legacy weed.

&#8226 Min-till encouragement.

&#8226 Limited herbicide controls.

&#8226 New chemistry success.