Problem plant species are often described as weeds. Weed plants are those which, when out of the natural balance of an ecosystem, can cause management problems for agriculture and conservation. Weeds can be unpalatable or toxic to livestock, can reduce hay yields or the abundance of desirable plants and may prevent management of benefit to wildlife. It is essential that action is taken to correct weed problems. The main way to prevent a weed problem is to avoid damaging the sward or creating large areas of bare ground.

• Over grazing
• Vehicle movement, particularly in wet weather
• Regular congregation of animals in one area, such as feeding stations
• Feeding with weed infested hay
• Nutrient enrichment

The choice of control method depends upon the weed species, the area affected, available resources, accessibility to the site and the intensity of the problem. A combination of the following approaches is likely to be most successful, particularly when carried out over several years and alongside a beneficial long-term grazing regime.

Grazing can be a cause of weed problems but is also essential in their control. Some weeds such as ragwort at low densities can be minimised by sheep grazing early in the season. Long-term control requires an appropriate grazing regime.

Weeds can be cut with hand tools just below ground level or pulled by hand and uprooted. Ideally, carry this out before flowers open and ensure that the plants are removed from the field and burnt. This is particularly important for ragwort which remains toxic when dead but loses its distinctive smell so may be eaten by livestock. This method is suitable for small areas or low densities of weeds and for regular, ongoing control.

Weeds can be pulled up with an Eco-puller - a tractor-trailed machine which grabs taller weeds, up-roots them and collects the plants for disposal. This method is suitable for large areas or dense weed problems and is a more fuel efficient method than cutting. Plants must be at least 30cms tall. Bracken can be controlled by bruising or crushing. Agricultural rollers are pulled over the plants destroying them. This method has to be repeated several times per year and over a number of years, to weaken the bracken’s rhizomatous roots.

The tops of plants can be cut off by hand or mechanical means. This method is most effective when plants have reached their full height, but before they have flowered to prevent seed setting. Carry out at least twice in a season, a month apart. Topping does not kill plants and can cause vigorous growth at the root perpetuating the weed problem. Caution should be exercised where ground nesting birds are present.

Several chemical options are available and the choice depends upon the type of weed and the context of the problem. Chemical treatment should only be undertaken when there is no fitting alternative and should only be used to deal with symptoms when the cause of the problem is also being addressed.

There are three common application methods: Spot spraying and weed wiping target chemical applications and so reduce chemical use and therefore costs compared to boom spraying, which should be used as a last resort. Follow chemical control instructions closely to maximise effectiveness minimise quantities.

The use of pesticides is controlled by law and Codes of Practice. Further regulations exist on designated sites and adjacent to waterways. Seek advice from appropriate bodies before undertaking works. The issue of chemical weed control is a complex one and this sheet aims only to provide an overview of the issues and options available.

To view a table of management techniques, please click on the image below.