Common ragwort can become a serious weed of waste or other uncultivated ground.
Ragworts (Senecio species) are poisonous weeds of which Senecio jacobaea is the most common. Cattle and horses are particularly susceptible to poisoning but it is rarely a problem in gardens. The Weeds Act specifies five injurious weeds: common ragwort, spear thistle, creeping or field thistle, broad-leaved dock and curled dock. The new 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.
Cultural control
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 control
Glyphosate can be used to clear small infestations but apply carefully as it will kill any green plants it comes into contact with. MCPA and 2,4-D are selective herbicides for use on areas of grass. They are effective against ragwort when applied at the higher rates mentioned on the product label. These herbicides also affect other broad-leaved plants such as clover.
To control mature plants in pastures apply herbicides 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. Herbicides 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.
Herbicides suitable for large-scale pasture use are available only to qualified professionals. Contact agricultural contractors to treat paddocks and similar areas (see Yellow Pages). For garden use only, consider using SBK Brushwood Killer in rough grassed areas and lawn weedkillers for lawns.
Full guidance on the various options are detailed in the Code of Practice appended to the Ragwort Control Act 2003 which is available online at www.opsi.gov.uk/acts/acts2003/20030040.htm
Printed copies of the Code can also be obtained from DEFRA Publications (please quote reference PB9840) at:
DEFRA Publications
ADMAIL 6000
London
SW1A 2XX
Tel: 08459 556000
William Denne