Keep ragwort from affecting nearby land.
Keep ragwort from affecting nearby land.
|Production threat||Environmental threat||Public threat|
Ragwort is an agricultural pest in the Waikato. It is a highly invasive pest plant which has unpalatable foliage, reducing pasture production throughout New Zealand. It is also found in waste places, riparian margins, open forest and swamps. Ragwort reproduces from crowns, roots and wind-borne seeds. Ragwort is more apparent on dairying and drystock properties and if eaten, its foliage is poisonous to cattle and horses.
All landowners/occupiers in the Waikato are responsible for controlling ragwort on their properties and are required to work with Waikato Regional Council in areas where control programmes are in place. If you graze the roadside then you are responsible for controlling this plant pest on that adjoining land. The level of control depends on where the property is.
See the map below for an overview of the locations of the two types of control zone.
Ragwort is also banned from being sold, propagated, distributed or included in commercial displays.
Some options for managing ragwort are included in this factsheet, but there are others. For more information contact your herbicide representative or check www.pestweb.co.nz.
Pulling plants out and disposing of them by deeply burying, burning or composting (if no seed heads are present) is an effective method of controlling ragwort. Plants are best pulled at the flowering stage where the roots are much less likely to regrow. Mowing ragwort is not recommended, as it will encourage the plant to become multi-crowned or to become a perennial plant, making it difficult to control. Ragwort is poisonous to cattle and horses but not sheep, so stocking ragwort-infested areas with sheep will reduce the number of plants.
Ragwort can be grazed by sheep or goats. However, cattle rarely eat ragwort seedlings or rosettes.
There are many herbicides that will control ragwort. The herbicide best suited to your property will depend on the level of infestation, the application equipment you have available and the stage of growth the plants are at. Some suggested herbicides are included in the table in this factsheet. Contact your local biosecurity pest plant officer for free advice on what herbicide and application method would best suit your situation on freephone 0800 BIOSEC (0800 246 732).
A boom/aerial application of herbicide will affect desirable species such as clover and ryegrass. This damage can be minimised by applying herbicide to ragwort plants in the seedling/rosette stage during autumn and early winter. Be aware that ragwort plants may become more palatable to cattle and horses after spraying. Stock should be removed until the treated plants die.
Small block owners who may not have access to spray equipment could consider physical control methods (see above) or select a herbicide such as picloram granules. Picloram is a dry application powder which does not require mixing or spray equipment.
A biennial or perennial daisy, ragwort grows to between 45-60cm high. It has masses of yellow flowers. However, recognising the juvenile plant is more difficult as the leaves look quite different once the plant has matured. Plants have an unpleasant smell when crushed.
Disclaimer: Any product names mentioned below are not an endorsement nor are they a criticism of similar products not mentioned.
Summary of herbicides and application methods for control
When to apply
|2,4-D||Up to small rosette||Slight||No||Slight|
|Dicamba||Up to large rosette||Severe||No||Severe|
|Triclopyr/picloram||Up to large rosette||Yes||No||Severe|
|Metsulfuron-methyl||Up to large rosette||Yes||Moderate||Severe|
|Picloram||Up to large rosette||Yes||No||Severe|
|MCPA||Up to small rosette||Moderate||No||Slight|
|Aminopyralid||Up to large rosette||Severe||No||Severe|
|Clopyralid||Up to large rosette||Severe||No||Moderate-severe|
|Thifensulfuronmethyl||Up to small rosette||Slight||Slight||Moderate|
|Mecoprop/dichloroprop/MCPA||Up to small rosette||Yes||No||Severe|
|Herbicide rules will apply. You may need to notify neighbours if spraying. The Waikato Regional Plan explains the agrichemical (herbicides) use rule in section 6.2|
Biological control involves importing insects or fungi that feed on plants in their native countries. Biological control agents reduce infestations but do not eradicate plants from an area. All the following biocontrol agents have been released throughout the Waikato and have established themselves in all suitable areas. If you have ragwort on your property you will still need to undertake control work.
Biocontrol agents released in the Waikato to attack ragwort include:
The ragwort flea beetle has had the most significant impact on ragwort in the region. In its larvae stage, the beetle feeds on the crown of the ragwort plant. Ragwort flea beetle was released in New Zealand in 1981 and has in places reduced ragwort from 60-98 per cent of its former density.
Landcare Research runs a national biological control programme. Waikato Regional Council supports the programme and maintains a local biological control programme for the Waikato region.
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