Also known as carduus nutans, musk thistle, nodding plumless thistle.
General description of nodding thistle
Nodding thistle is an aggressive biennial (sometimes annual) thistle growing to about 1.6 metres, reproducing by seed. The leaves are dark green with whitish margins deeply divided into triangular lobes with spiny tips. Flowering nodding thistle are recognised by their large red-purple flower heads that droop.
Impact on the environment
Nodding thistle is a major agricultural pest, smothering grass and forming a total ground cover that prevents stock movement. Each nodding thistle plant can produce from 7,000 to 30,000 seeds.
Regional Pest Management Strategy
Gisborne District Council's Regional Pest Management Strategy lists nodding thistle is a 'total control' pest plant.
Council's plant biosecurity officers carry out regular site inspections on a 6-8 week rotation of infected properties between October to March each year. Random site monitoring is also carried out during the winter period.
To assist land occupiers in site location and identification, each individual nodding thistle site has been pegged with a white painted batten firmly fixed into the ground and a numbered plastic tag nailed to each peg. The position of all nodding thistle sites is then recorded by GPS for long term monitoring. This identification system helps staff collect data from sites and is a quick reference for land occupiers of those sites that have thistle infestations which need to be controlled.
It's important that land occupiers with nodding thistle infestations maintain a regular maintenance programme to control the spread before seed is produced.
Where land occupiers fail to carry out proper control measures to the required standards, Council can use regulatory measures to achieve compliance.
Report any sightings of new nodding thistle to Gisborne District Council. Our plant biosecurity staff can help by giving advice on the best control methods.
How to control nodding thistle
This is one pasture weed that land owners and occupiers with active plant infestations can't ignore. Any infestations require you to carry out regular checks and control work before the plants produce seeds. Here's some advice:
- broadcast spray during the autumn or early spring to remove seedlings and small plants
- follow up with spot spraying or grubbing to catch late germinating or missed plants
- infested areas must be checked at least twice a year to make sure the plants don't seed
- grub or spray plants before they flower
- keep a tight sward of grass and do not overgraze. This prevents germination or suppresses the majority of seedlings before they develop
- use a controlled grazing regime, subdivide paddocks with electric fencing to allow pasture to lengthen
- don't buy uncertified seed or hay from an unknown source
- make sure any machinery entering your property has been thoroughly cleaned