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.
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 more palatable to livestock and poisoning mainly arises from eating contaminated hay.
Common ragwort produces large numbers of seeds which are dispersed by the wind.
The Weeds Act specifies five injurious weeds: common ragwort, spear thistle, creeping or field thistle, broad-leaved dock and curled dock. The Ragwort Control Act 2003 (which amends the Weeds Act 1959), imposes a duty of responsibility on landowners to effectively control Senecio jacobaea, preventing its spread onto grazing land.
Full guidance on the various options as detailed in the Code of Practice appended to the Ragwort Control Act 2003 is available online at the Office of Public Sector Information website.
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.
Glyphosate (e.g. Scotts Roundup Ultra 3000, Scotts Tumbleweed, Bayer Tough Rootkill, Bayer Garden Super Strength Weedkiller or Doff Maxi Strength Glyphosate Weedkiller; 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 Vitax LawnClear 2, Westland Resolva Lawn Weedkiller Concentrate or Doff Lawn Spot Weeder) 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.
Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 1a and b, and 4)
Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale weedkillers