Environment

Ragwort

Ragwort with bright yellow flowers.Ragwort with bright yellow flowers. Common name:
Ragwort

 

Scientific name:
Senecio jacobaea

 

Regional classification:
Ragwort is recognised as posing significant threat to the Northland Regional Council’s natural ecosystems because of its wide distribution and invasive characteristics. Ragwort is unable to be distributed, offered for sale or held on premises where plants are offered for sale.

Description

A member of the daisy family, ragwort is an erect annual, biennial or perennial herb. It usually grows to 45 - 70 centimetres in height, but can reach 1.6 metres.

 

Roots:

  • solid taproot produces numerous fibrous roots
  • extend outwards 30 centimetres or more

Leaves:

  • wrinkled and deeply divided
  • appear in a rosette that grows into a dense cluster or ‘cabbage’

Stems:

  • follow a few months after the cluster of leaves
  • streaked red-purple
  • dotted with leaves

Flowers:

  • bright yellow, maturing to brown
  • produce many tiny seeds surrounded by white, feathery, thistledown-like hairs

Seeds:

  • numerous seeds dispersed by wind, water, animals, vehicles, clothing and hay etc.
  • can also spread from root or crown fragments

Why is it a problem?

The major threat posed by ragwort is to seasonal pasture production and profit. It is an aggressive invader that soon becomes dominant cover, and is also toxic to stock, especially cattle and horses.

Recommended control methods

Many different control methods exist, but no single method can give permanent control of ragwort. A combination of dedicated pasture management, biological control and ragwort removal is needed to maintain clean pasture.

 

Maintaining a vigorous dense pasture greatly assists in preventing ragwort invasion.

 

Biological:

 

The ragwort flea beetle has proved an effective biological control agent on ragwort. 
Find out more about the ragwort flea beetle

 

Grazing:

 

Is not recommended as ragwort is toxic to livestock. The plant contains several poisonous alkaloids and prolonged grazing leads to chronic liver damage.

 

Grubbing or pulling:

 

This not the ideal control method as it leaves root fragments in the soil that resprout into multi-crowns. Either of these actions should only be considered when plants are at the full-to-late flowering stage and the soil is very dry, as root fragments will then die. Use rubber gloves when hand pulling, as ragwort is poisonous and can be absorbed through the skin.

 

Chemical control:

 

Herbicides probably give the best short term results, but can kill clovers which are vital for pasture production. Some also check or kill grasses.

 

Weedwipe in summer, only, using 300 millilitres of glysophate plus 2 millilitres of penetrant to 1 litre of water, or

 

Spray rosette plants from winter to spring, before the stems have formed, using 2,4-D ethylhexyl ester 2 -4 litres in 100 – 200 litres of water per hectare, or

 

For mature plants, spray until flowering using 100 millilitres of glysophate per 10 litres of water.  

Note: When using any herbicide PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed. 

More information

For further information or control advice please contact one of our Biosecurity Officers at the Northland Regional Council on 0800 002 004:

  • Whāngārei: Sara Brill
  • Dargaville: Carl Cooper
  • Kaitāia: Doug Foster