Common ragwort supports a wide variety of invertebrates, including nationally rare or scarce species and 30 that are entirely reliant on this distinctive plant.
Ragwort is often over controlled unnecessarily where it is seen as presenting a risk to livestock due to its toxicity. Although it is a poisonous plant, the living plant is unpalatable and is usually avoided by livestock, unless there is no other source of food. However, it does becomes more palatable when dry hence the need to control it in fields cut for forage.
It is typically found in grassland and unmanaged ground as it readily colonises bare patches of earth. Where it prevents a risk to livestock, such as in or adjacent to grazing fields or those used for the production of forage it should be controlled. Where it prevents no risk to livestock and is not spreading it should be regarded as part of the native flora and be left to flower.
Ragwort is a biennial when undisturbed but can become a perennial if mown or grazed. The young plant appears as a dense rosette of basal leaves that is most obvious from autumn to June, but is usually visible all year round. The leaves are deep green in colour, deeply cut and toothed giving the ragged appearance from which the plant derives its name.
In the second or subsequent year from June onwards, flowering stems, about 30—100cm high, are produced. These bear flat-topped clusters of characteristic bright yellow daisy-like flowers. The flowers mature into white seed-heads containing large numbers of downy seeds.
The wind-dispersed seeds ripen from August onwards. They may remain dormant in the soil for more than 15 years.
Although common ragwort is the most widespread ragwort species, three others are found in Britain: marsh ragwort, Oxford ragwort and hoary ragwort. These other species are not common and are not covered under the Weeds Act.
Good practice control
The best way to prevent the spread of ragwort is to practice good agricultural management. Ragwort is as an opportunist, colonising bare ground so it is important to avoid damage to the sward. In a well-managed sward, ragwort seldom gets the chance to establish as a dominant plant.
Overgrazing, overstocking, rutting caused by vehicle movement and poaching by animals can all create areas of bare ground where ragwort can establish. To avoid such problems it is necessary to adopt appropriate grazing levels for the area of land and to prevent over-grazing by moving the livestock around different fields or sub-dividing an individual field.
The aim is to keep a sward height of at least 5 cm throughout most of the grazing period. Where possible, removal of animals when the ground is wet or when supplementary feeding is necessary reduces the chance of bare patches forming.
Similarly, under-grazing, or badly timed cutting, can result in a tussocky, loose sward rather than a close mat, which allows ragwort to colonise. However even well managed grasslands often naturally contain some ragwort and the management regime will be dependent upon the particular requirements of the site. Our section on managing grasslands for wildflowers could be useful here.
Assessing the risk of ragwort
Ragwort only needs to be controlled where it presents a risk to livestock, either where it is within a grazing field or forage field, or is at risk of spreading easily to the above. In general if it is not in close proximity to any of these sites and the seeds are not likely to be blown there directly, it does not present a risk.
Where it is not a risk but has become dominant, changes in management should be sufficient to reduce its dominance over time. Where a small amount of ragwort is present in a field with livestock and there is plenty of other grazing present then it can be left as it will not be eaten due to its unpalatable taste.
The exception to this is sheep which will often eat small amounts of ragwort in the rosette form with no ill effects and therefore can be useful for supressing its growth.
Pulling and digging - If control is necessary then for small amounts of ragwort pulling is often the easiest method. A specialist long hand tool, such as the ‘lazy dog’, can be used to remove the tap root without the stem of the plant breaking. When removing plants in this way it is necessary to ensure that all traces of root have been removed, as small fragments can develop into new plants.
This is most easily carried out when the ground is damp. Ideally the plants should be removed before they have completed flowering. It is always advisable to wear gloves when dealing with ragwort.
All pulled or dug ragwort material needs to be removed from the site and destroyed by burning or composting in a sealed bin for 12 months, as grazing animals are particularly at risk from the dried plant which becomes palatable but remains poisonous.
Cutting - This is a last resort and stimulates growth, so should only be used to prevent immediate seeding where no other control method can be employed. If cut, the plants can re-flower later in the season or change from a perennial to a biannual, flowering the following year. Any cut plants are toxic and more palatable to livestock and should be removed from the field.
Ragwort has been specified in the Injurious Weeds Act so it is important to try to control the plant and prevent its spread to neighbouring land. For more information see the DEFRA website www.defra.gov.uk