17 May 2002

DOCKSFIGHTGRASS:KEEP EM DOWN

Docks dont make good

silage, so get rid of them

HIGH-INPUT silage leys provide the perfect conditions for docks to thrive and left uncontrolled they will reduce yield, forage quality and multiply. Although early control is preferable, there are still opportunities to take out docks in grass and clover swards, according to industry experts.

Docks compete aggressively with grasses for space, light and moisture, are the most economically damaging grassland weed and have 35% less feeding value than grass. And if docks become established in a silage sward a vicious cycle can be set in motion, according to Alan Hopkins of IGER.

Ensiled docks are fed to cattle from which, along with viable dock seeds, slurry is spread back onto the fields. "With docks producing many thousands of seeds per plant, up to 60,000 seeds from one plant have been recorded, infestations can soon spiral out of control unless action is taken to break this cycle," he says.

Dock seeds are highly persistent and will lie dormant in the soil for several decades. "When resowing, robust seed rates will give the grass and clover opportunity to out compete emerging docks," explains Mr Hopkins. "In grazed leys, docks can be prevented from flowering and shedding seeds by tight grazing with sheep or frequent mowing. However in silage leys, herbicide treatment is really the only control option."

Clare Bend, technical manager for Masstock, points out that historically, effective control of docks has been a challenge in mixed grass and clover swards because many existing herbicide options take out or check clover. "In addition some products are subject to LERAP restrictions, limiting use where grassland borders ditches and watercourses," she explains.

"Recently introduced grassland herbicide Squire (amidosulfuron) could be a useful option as it doesnt require a LERAP and controls all dock species and a range of broad-leaved weeds without damaging white clover in the sward," she suggests.

While it may be preferable to control docks earlier in the spring it is still possible to treat them in grass and clover leys with Squire between first and second cut.

"Control of docks between cuts will help to optimise yield and feeding quality from the second cut and more crucially limit the build-up of dock populations for future years," concludes. Clare Bend &#42

Docks can be treated early

in spring or between

first and second cut.

Up to 60,000 seeds from one dock plant have been recorded, says Alan Hopkins.