Expert tips to control soft rush in grassland

It is estimated that about 10% of the UK’s 5.18m hectares of rough grazing is in-bye pasture that is at risk from soft rush.

A dense and unpalatable plant, it shades out grass and can reduce production significantly.

Below, NuFarm’s Brent Gibbon and independent grassland consultant George Fisher offer advice on how to control and prevent this pernicious plant.

See also: A guide to soil mapping and variable-rate fertiliser

What is soft rush and what causes infestations?

Soft rush (Juncus effuses) is a perennial plant often found in the wettest areas of fields or alongside watercourses.

Infestation is mainly a problem in permanent pasture and rough grazing.

It thrives in waterlogged and acidic soils and is spread by creeping rhizomes in the soil. A single rush seed head can produce 8,500 seeds each year, which can be easily dispersed in the wind.

Rushes are tall and dense plants that shade out grass. It flowers at the end of June, presenting a “tuft”. A 10% infestation can reduce grass production by 10%.

How do you prevent it?

The plant favours acidic and wet soils, so key control measures include:

• Maintaining good field drainage
• Ensuring soil pH is 6.5
• Avoiding damage to swards by overgrazing, which can lead to poaching and bare patches where rushes can establish
• Sowing grass seed mixes that are persistent and tiller aggressively to provide competition to rush seedlings.

How do you control soft rush?

Plants should receive a herbicide application in June, pre-flowering to give the best results.

There are two application and chemical control options:

• A boom sprayer using an MCPA herbicide, which is safe to grass.
• Weed wiper using glyphosate. This requires rushes to stand taller than grass, so only the rush gets treated. This treatment method is best for water catchment sensitive areas to prevent herbicides from contaminating watercourses. Free hire is available through some water authorities. Contact your local authority to find out if free hire is available in your area.

Once the rush has died off, plants will turn a sandy brown colour. Rushes should be cut using a topper or mower to remove the dead material, allowing grass to regenerate.

It will typically take one month for the plant to die and for the chemical to reach the root and kill the rhizomes.

If there is any regrowth, farmers should retreat.