Couch control a welcome Attribut

29 June 2001

Couch control a welcome Attribut

By Tom Allen-Stevens

THE first grass weed herbicide to tackle couch in growing cereal crops gained official approval from the Pesticides Safety Directorate on Thursday (28 June).

Attribut (propoxycarbazone-sodium) is a residual, spring-applied herbicide that also has useful activity against blackgrass, says manufacturers Bayer.

It also knocks back sterile brome and will suppress other grass weeds such as onion couch, wild oats and loose silky bent, says the company.

In 5 years of extensive trials work Attribut reduced the number of couch weed biomass by an average of more than 90% and rhizome growth by over 75%.

Treatments in Bayer trials last year were applied at two timings; in late April when the couch grass was at GS 11-14 and a month later at GS 31.

In the untreated plots the crop was swamped with a mass of couch grass, while the split dose applications gave almost 100% control and a yield advantage of 2.2 tonnes per ha.

In blackgrass trials, when used in sequence after various autumn blackgrass killers, weed numbers were reduced by up to 99%.

In a Northamptonshire trial last year with a known sterile brome problem, the crop received pre-emergence Avadex (tri-allate) and post-em IPU.

Attribut was applied in the spring and gave 73% control of sterile brome, while sulfosulfuron in the same sequence gave only 39% control.

Previously, the only way to control couch in the standing crop was with a post-senescence application of glyphosate.


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