Clean up silage leys before first cut

UK - February 22, 2010



An early assault on docks growing in grass leys will protect silage yields and quality according to weed control specialist Duncan Connabeer, technical support manager for H L Hutchinson.

“Docks are bad news in grassland as they compete for light, nutrients and moisture,” explains Mr Connabeer. “Trials have shown that a 10% infestation of docks will cause 10% loss of grass; equivalent to one trailer load of silage in ten.

“Docks are also unpalatable with only 65% of feed value of grass. They also adversely affect silage fermentation which reduces feed quality still further.”

Docks are a formidable foe, with an estimated 15% of productive grassland infested and a potential seed bank of 12.5million seeds/ha in the top 15cm of soil.

Fields used for silage are most at risk due to the open nature of the sward, which allows established docks to spread and viable seeds to germinate.

Treatment starts in March
“In the south, treatment could start as early as the end of March - as long as docks have reached the rosette stage and are actively growing, and look green and healthy. Reddy blue leaves indicate that plants have been frosted, and herbicide uptake will be poor.

“Docks respond well to nitrogen, so a good time to spray is two to four weeks after the first fertiliser application, as they should be actively growing by then.

“If it is not possible to treat pre-first cut, leave the aftermath for two to three weeks to allow sufficient re-growth before spraying. This will give good control, as weeds will be at a uniform stage of development,” says Mr Connabeer.

Grass-safety
When treating weeds early it is important to select a herbicide that will not damage the grass.

“Translocated herbicides, such as Doxstar, control target weeds without checking the important first flush of spring grass,” says Robin Bentley grassland herbicides product manager for Dow AgroSciences. “So docks can be tackled early without concern.

“The first cut of silage is crucial for both yield and quality and it is important not to compromise this. Modern translocated herbicides do a good job on weeds without adversely affecting grass. The way they work also gives longer lasting control, so users can still benefit two to three years after treatment.”