Ragwort

Ragwort (Senecio jacobaea) is native biennial which is a food souce for a wide range of insects. It 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

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 found throughout the British Isles in grassland, verges, waste land and negelected or over-grazed pastures. Its flowers are attractive to a wide range of insects including butterflies and moths. The distinctive yellow and black striped caterpillars of the Cinnabar moth are often seen feeding on the foliage. In gardens, ragwort can be a welcome food source for many insects and a cheerful addition to a flower-rich meadow, provided this is not near paddocks grazed by horses and livestock. Learn more about making the most of lawns as a wildlife habitat and ways to help our bees and butterflies;




Ragworts (Senecio spp.) are poisonous weeds of which Senecio jacobaea is the most common. Their seeds are spread by wind and a single plant is capable of producing 50 - 60 000 seeds. It can become a major weed of waste or other uncultivated ground. This page looks at options for gardeners when ragwort is becoming a problem.

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

First, consider whether this can be done using non-chemical means such as digging out and where this is not feasible, chemical controls may need to be used.

The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.

Cultural control

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.

Weedkiller control

Glyphosate

Glyphosate (e.g. Roundup Ultra, SBM Job done Tough Weedkiller (soluble sachet only), Doff  Advanced Concentrated Weedkiller or Westland Resolva Pro Xtra Tough Concentrate; or for spot treatment use 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 (Vitax LawnClear 2) are selective weedkillers that are effective against ragwort when applied at the higher rates mentioned on the product label. These weedkillers are also effective on other broad-leaved plants such as clover

In rough grass use a selective weedkiller which contains triclopyr (SBK Brushwood Killer) as this would leave the grass unharmed. However, other broad-leaved plants will be damaged (e.g. wildflowers) and so should only be used in grass where such action is acceptable. For garden use only, consider using triclpyr (Vitax SBK Brushwood Killer) in rough grassed areas and lawn weedkillers for lawns.

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 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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