Greenham and Crookham Commons Management Plan 2009-2014: Ragwort

Ragwort (Jacobaea vulgaris, formerly Senecio jacobaea) on
Greenham and Crookham Commons

Ragwort grows widely across the commons. Populations naturally tend to be greatest in the open, sparsely vegetated or grassed areas. However, scattered individual plants can in some years be found in almost any part of the site. The population varies greatly from year to year.

Ragwort contains toxins which can have debilitating or fatal consequences, if eaten by horses and other grazing animals. It is less likely to be rejected by livestock if dried, so contamination of forage (hay, haylage and silage) is a particular problem. Humans may be at risk from ragwort poisoning through direct contact (e.g. hand pulling) or the consumption of contaminated food.

Under the Weeds Act 1959 the Secretary of State for the Environment, Food and Rural Affairs can, if satisfied that injurious weeds are growing upon any land, serve a notice requiring the occupier to take action to prevent the spread of those weeds. An unreasonable failure to comply with a notice is an offence.

Two risks will be monitored and, if necessary, mitigated:

The ecological value of ragwort is well recognised. The cinnabar moth (Tyria jacobaeae) occurs on the commons. As a species "of principal importance for the purpose of conserving biodiversity" the Natural Environment and Rural Communities Act 2006 requires public bodies to consider it when performing their functions with a view to conserving biodiversity [1]. One hoverfly and four beetle species with a high dependency on ragwort are recorded in the two 10 km squares which encompass the commons [1, 2]. Two of the beetles are designated nationally scarce or nationally notable.

There is, therefore, no intention to implement a blanket control policy unless there is evidence, or a strong likelihood, of risk translating to actual harm.

There is no historical evidence that livestock on the commons habitually eat ragwort. General opinion is that stock avoid it as long as there is alternative forage. However, a long hot dry summer can result in the grass and other plants shrivelling, leaving ragwort as one of the few plants with any green left in it. This presents a risk that livestock will resort to eating it. Also, in such conditions there may be a microclimate with a little extra dampness right beneath the rosettes of ragwort leaves, supporting a few blades of still-green grass. Cattle may accidentally consume ragwort when trying to get at these [3].

Herbicide control should not be used on ragwort plants which have already developed the central flower spike, because the dead plants lose their unpalatable taste and this would increase the risk of ingestion. Hand-pulling or levering plants out has been tried in the past, but soil conditions on the common (especially in dry conditions described above) make these control methods almost impossible to use effectively. In such conditions the best control is to remove some or all of the livestock.

The overall approach to managing ragwort is therefore:


[1] Ruth Laybourn, Debbie Kessell, Naomi Jones, Simon Conyers, Caroline Hallam, Nigel Boatman, 2013. Review of evidence concerning ragwort impacts, ecology and control options. Food and Environment Research Agency

[2] National Biodiversity Network: NBN Gateway, hectads SU46 &SU56 (accessed 09 Mar 2015):

  • Hoverfly, Cheilosia bergenstammi: SU46 & SU56
  • Beetle (nationally scarce), Longitarsus dorsalis: SU46
  • Beetle (nationally scarce), Longitarsus ganglbaueri: SU46
  • Beetle, Longitarsus gracilis: SU46
  • Beetle, Longitarsus jacobaeae: SU46
  • Moth (BAP priority species), Tyria jacobaeae: SU46 & SU56

[3] C Austin, Greenham & Crookham Commons Commission meeting 17 Feb 2015

[4] DEFRA, 2004. Code of Practice on How to Prevent the Spread of Ragwort

Ragwort risk assessment by subcompartment

Whether or not each area is grazed, and how close it is to adjoining land which may be used for hay or grazing, varies very little or not at all from year to year. Relative susceptibility to colonisation by ragwort (for example vegetation type, amount of open ground, tree cover) also shows very little change from year to year (but will be reviewed if, for example, large areas of tree or scrub cover are removed). A breakdown by compartment and subcompartment is shown below.

Table 1: Risk factors likely to remain constant for each subcompartment

Grazing stock: cattle/ponies/pigs = 2, sheep/goats = 1, no grazing = 0
Proximity to adjoining grazing land: <50 m = 2, 50 to 100 m = 1, >100 m = 0
Ragwort susceptibilty (soil conditions, vegetation, tree cover): high = 2, medium = 1, low = 0

Inspection frequency (derived from total risk score):
0 = Never, only if passing through or if highlighted by a third party, 1-3 = Biennially, 4-6 = Annually

Comp. Subcomp. ha Locale Grazing
Proximity to
grazing land
Total Inspection
01 01A 4.1 Near Pyle Hill gate 2 2 1 5 A
01B 10.7 End of runway 2 2 2 6 A
01C 9.6 Sandleford Heath 2 1 2 5 A
01D 9.8 Sandleford Woods 2 2 4 A
02 02A 11.1 Brackenhurst Heath 2 1 3 B
02B 6.8 Peckmoor Copse 2 2 B
03 03A 7.6 Aldernbridge Gully 2 2 B
03B 11.9 Aldernbridge/Ballshill Heath 2 1 3 B
03C 7.3 Ballshill Gully, Handpost Gully & Peaked Hill 2 2 B
03D 3.8 Adjacent to east side of GAMA site 2 2 B
03E 10.2 NW of fire plane area 2 2 4 A
04 04A 4.6 Clarke's Gully 2 2 B
04B 9.2 Bishops Green Heath 2 2 B
04C 7.2 East of Bishops Green Road N
05 05A 8.4 Martindale 2 2 B
05B 1.4 South of Thornford Road near A339 junction 2 2 B
05C 9.6 Heads Hill & Goldfinch Bottom 2 2 B
05D 8.7 Brushwood Gully 2 2 4 A
05E 0.4 South of Thornford Road 2 2 B
06 06A 18.6 Crookham Common east of Old Thornford Road 1 1 B
06B 3.9 Thornford Gully N
07 07A 2.4 North of Crookham Road (w) 2 2 B
07B 7.4 North of Crookham Road (e of 7A) 2 2 B
07C 1.3 North of Crookham Road (e of 7B) N
07D 12.6 South of Crookham Road 2 2 B
08 08A 12.0 2 2 4 A
08B 4.9 2 2 4 A
08C 8.5 2 2 4 A
09 09 19.4 Northeast "lozenge" of former runway/taxiway area 2 2 4 A
10 10 19.4 Southeast "lozenge" of former runway/taxiway area 2 2 4 A
11 11 20.6 Northwest "lozenge" of former runway/taxiway area 2 2 4 A
12 12 19.6 Southwest "lozenge" of former runway/taxiway area 2 2 4 A
13 13 7.0 Area to the south of the estern cattle grid on BBR 2 2 4 A
14 14 19.5 Main car park, control tower and adjacent area 2 2 4 A
15 15 7.6 Northwestern areas of Greenham Common 2 2 4 A
16 16 77.5 Former runways and subsidiary areas 2 2 4 A
17 17A 1.0 Pigeons Farm Road N
17B 9.7 Approach to Bowdown Woods 2 1 3 B
17C 1.7 2 1 3 B
17D 5.1 2 1 3 B
17E 0.7 N
17F 0.3 Entrance to Pigeons Farm track N
17G 1.1 East of Crookham Golf Club N
17H 0.1 2 1 3 B
18 18 31.0 Crookham Pools or relandscaped area 2 2 2 6 A

The relatively unchanging risks in each subcompartment have been used to determine the inspection frquencies in the rightmost column of table 1 above. Inspections, at the frequencies shown, will be carried out to quantify risks which tend to vary from year to year with the naturally volatile ragwort population and (for instance) the availability of other forage due to weather conditions and grazing numbers. Subcompartments will be scored using table 2, below. If the score is 5 or above then ragwort management will take place in that subcompartment using the methods outlined. This policy will be adhered to wherever possible and practical. If, however, there are overriding reasons to increase or decrease ragwort management then these will be taken into consideration.

Table 2: Risk factors to be assessed periodically for each subcompartment

Factor High = 2 Medium = 1 Low = 0 Score
Density of plants > 10 plants per m2 2 - 10 plants per m2 < 2 plants per m2
How much alternative forage is available? Not much, the site is heavily grazed Enough at present, but heavy grazing might reduce availability Plenty of forage available
Will a hay cut be taken? Yes, a hay cut will be done where the ragwort is No, but it might be cut the following year No, this area will never be cut for hay
Is the extent of ragwort changing? Extent is increasing Extent is naturally constant Extent is naturally decreasing
Are the livestock exposed to ragwort for an extended period? Yes, they will be exposed to ragwort over a number of years Livestock may be exposed to ragwort repeatedly during their life Livestock are unlikely to be exposed to ragwort again