Woodrush in lawns

What is field woodrush?

Field woodrush is largely a problem in lawns, particularly under the following conditions;

• It is common in acid conditions, especially where thatch (accumulated dead, fibrous material) has built up and increased acidity. Under such conditions grass growth is too weak to prevent this troublesome weed from establishing
• Field woodrush even grows in chalk and limestone areas where the upper layer of soil has become acidic, due to rainfall and acid-reaction fertilisers such as sulphate of ammonia

Appearance

Field woodrush (Luzula campestris) is a grass-like perennial. Its broad-bladed, dark green leaves, are fringed with long, silky hairs.

In March or April it produces dark brown flower and seed heads. These are particularly noticeable before mowing has begun.

It spreads via short, creeping stolons (above ground stem).

Control

Plants that out-compete other more desirable plants or simply invade half the garden are classed as weeds and require control. First, consider whether this can be done using non-chemical means such as forking out. Where these methods are not feasible, chemical controls may need to be used. Choose a weedkiller that is most appropriate for that purpose by reading the label carefully before buying or using.

Non-chemical control

The best way to eradicate field woodrush and prevent it coming back it to apply lime.

Apply ground chalk or ground limestone in late autumn or early winter, after mowing has ended, at 60g per sq m (2oz per sq yd). Do not use hydrated lime.

Many nitrogen fertilisers acidify the soil and are best avoided. Sulphate of ammonia is particularly acidifying. Most lawn feeds won't significantly affect pH, but where high nitrogen fertilisers are needed consider chicken manure pellets or nitro-chalk (also sold as Nitratechalk) which should be neutral in effect, rather than sulphate of amonnia.

Chemical controls

Field woodrush is resistant to lawn weedkillers, but those containing mecoprop-P (e.g. Doff Lawn Spot Weeder, Westland Resolva Lawn Weedkiller or Bayer Lawn Weedkiller 2) may check growth if repeated applications are made and the soil pH is raised by liming.

Download

Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 1b and c)

Links

Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale weedkillers