Ragwort

Ragwort (Senecio jacobaea) is not usually a significant problem in gardens, but its poisonous qualities can make it a serious weed of paddocks and gardens backing onto fields grazed by horses or cattle.

Common ragwort. Image: RHS

Common ragwort. Image: RHS

Quick facts

Common name Common ragwort
Latin name Senecio jacobaea
Areas affected Waysides, grazing land and uncultivated ground
Main causes Weed poisonous to cattle and horses
Timing Seen from spring to autumn; treat in late spring or autumn

What is ragwort?

Ragworts (Senecio spp.) are poisonous weeds of which Senecio jacobaea is the most common. It can become a major weed of waste or other uncultivated ground.

Appearance

Ragwort is a tall erect plant to 90cm (3ft) bearing large flat-topped clusters of yellow daisy-like flowers from July to October. It has finely divided leaves with a basal rosette of deeply-cut, toothed leaves.

The plant is usually a biennial (living only two years and flowering in its second year) but damage to the base of the plant can make the plant behave like a perennial (living indefinitely), as new rosettes are formed.

The problem

Ragwort is rarely a problem in gardens but may occur in pony paddocks, railway embankments and areas of unimproved pasture. Cattle and horses are particularly susceptible to poisoning. Cutting, wilting and the treatment with herbicides make ragwort less unpalatable to livestock and poisoning mainly arises from eating contaminated hay.

Common ragwort produces large numbers of seeds which are dispersed by the wind.

Ragwort is covered by the Weeds Act 1959 (which specifies five injurious weeds including common ragwort) and the Ragwort Control Act 2003. For guidance, on good practice and the legal framework for land managers, consult the Code of Practice on How to Prevent the Spread of Ragwort.

Control

Non-chemical controls

Non-chemical options are limited. Cutting at the early flower stage reduces seed production but can stimulate the growth of sideshoots, resulting in more vigorous growth in the following year. Cut plants are a serious risk to grazing animals and may still set seed. They should be removed and burnt.

Pulling is practical where weed numbers are low, but the benefit is only temporary. Roots remaining in the soil will give rise to new plants.

Chemical controls

Glyphosate

Glyphosate (e.g. Scotts Roundup Ultra, SBM Job done Tough Weedkiller (soluble sachet only), Doff  Maxi Strength Glyphosate Weedkiller or Westland Resolva Xtra Tough Concentrate; or for spot treatment use Scotts Roundup Gel) can be used to clear small infestations but apply carefully as it will kill any green plants it comes into contact with.

Lawn and grassland weedkillers

In more heavily infested grassed areas, MCPA and 2,4-D (e.g SBM Job Done Lawn Weedkiller or Vitax LawnClear 2) are selective weedkillers that are effective against ragwort when applied at the higher rates mentioned on the product label. These weedkillers also affect other broad-leaved plants such as clover.

To control mature plants in pastures apply weedkillers in late April or May. Grazing is not safe for at least four to six weeks after spraying as treated plants remain poisonous. Allow plenty of time for the weeds to decay. Established plants are less susceptible to spraying, particularly after the stem elongates in early June. Spraying from September to November during mild and settled weather will control summer seedlings.

Spraying has to be a routine procedure every autumn, or every second spring, as ragwort seeds remain viable in the soil for up to 15 years. Weedkillers temporarily increase the attractiveness of ragwort to grazing stock, so to be sure of preventing poisoning, keep animals off sprayed pastures until the weed has disintegrated and disappeared.

Weedkillers suitable for large-scale pasture use are available only to qualified professionals. Contact agricultural contractors to treat paddocks and similar areas (see Yellow Pages or the National Association of Agricultural Contractors). For garden use only, consider using triclpyr (Vitax SBK Brushwood Killer) in rough grassed areas and lawn weedkillers for lawns.

Inclusion of a weedkiller product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.

Download

Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 1a and b, and 4)

Links

Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale weedkillers
Weeds: non-chemical control


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