Under the Weeds Act 1959, the Secretary of State may serve an enforcement notice on the occupier of land on which injurious weeds are growing, requiring the occupier to take action to prevent the spread of injurious weeds.
The Weeds Act specifies five injurious weeds: Common Ragwort, Spear Thistle, Creeping of Field Thistle, Broad Leaved Dock and Curled Dock.
It is the horse and pony owner's duty to ensure that their animals are protected from Ragwort and to remove those plants which pose a risk to animals. Paddocks and fields should be frequently walked to make sure that they are free from harmful plants, and good basic plant identification skills should be learnt.
Fences should be regularly checked to ensure that they not only prevent animals from straying, but also protect them from poisoning themselves by eating harmful plants.
Good relations with your neighbours are important for many reasons, not least to make certain that they are aware of the risks to your animals from garden plants! Poisonous plants in gardens include Yew, Privet, Foxgloves, and Deadly Nightshade.
Ragwort
Common Ragwort (Senecio Jacobaea) is poisonous to horses and other livestock and can have potentially fatal consequences if ingested either in its green or dried state. Over 90 per cent of complaints that The Department for Environment, Food & Rural Affairs (DEFRA) receives about injurious weeds concern ragwort. The Ragwort Control Act came into force in 2004.
Amending the Weed Act, it provides added protection to horses and allowed for the production of a 
Code of Practice on How to Prevent the Spread of Ragwort and the supplementary Guidance on the Disposal Options for Common Ragwort. Both are recommended reading for horse-keepers and can be downloaded from this website or obtained from the Natural England office listed below.
DEFRA can take enforcement action requiring an occupier of land on which ragwort is growing to take action to prevent the weed from spreading onto land used for grazing, forage production or other agricultural activities.
A
weeds complaint form and
DEFRA Information Sheet are available if you wish to complain about an infestation of injurious weeds as specified in the Weeds Act 1959.
A complaint form is also available from the Natural England office listed below.
Please note that completed complaint forms should be returned to the appropriate Natural England office for this area.
Cambridge Office
Natural England
Zone A, Eastbrook,
Shaftesbury Road,
Cambridge CB2 8DR
Telephone: 01233 533588
Bedfordshire, Cambridgeshire, Essex, Hertfordshire, Norfolk, Suffolk
Attention: attached is a list of some of the most common
Poisonous Plants that you may come across in Hertfordshire.
