Common name: Royal fern
Botanical name: Osmunda regalis
Management category: Sustained control - Rule 5a applies
Royal fern originates from Europe, west Asia, India, Africa and America. It’s deciduous (does back in winter) and is hard to miss with large fronds growing up to 3m long and 75cm wide. Naturalised in New Zealand by 1890, its fibres were used as a potting medium to cultivate orchids.
Why is it a pest?
- It reproduces by spores which are dispersed by the wind, making it difficult to contain its spread.
- It naturalises easily and quickly dominates its habitat, preventing native plants from growing.
- Significant threat to wetland habitats due to its ability to produce spores for most of the year and distribute easily.
- Can also spread via root fragmentation.
Where is it found?
- Prefers wet, peaty habitats, drains and occasionally edges of freshwater margins.
- Often found under grey willow and mānuka plants.
- Has been found in isolated areas of western Bay of Plenty and Rotorua.
What does it look like?
- It is quite a tall fern. It can grow to 2m in height and fronds can span out 3m.
- Reddish brown spores appear in late spring to autumn.
- Distinct yellow colour of foliage in autumn.
- There are no flowers on this plant.
- Leaves are hairless, except when young. They also turn red-brown in autumn.
- Roots are black and extend quite deep into the ground.
What are the rules?
Sustained Control pests are well established in the region and preventing the spread is no longer a realistic objective. Management focuses on reducing general impacts of the pest. Landowners/occupiers are responsible for the control of these pest species on their land. Council may enforce control.
Under rule 5a of the RPMP landowners/occupiers must destroy this pest if required by a written direction from an authorised person unless a property specific pest management agreement has been agreed and signed between the occupier and the Council.
Criteria to meet Rule 5A include when the species is being actively managed by council, other agency and or community group, on an adjacent property. See the Regional Pest Management Plan 2020-2030 rules for Sustained control pests for more information.
How do you get rid of it?
Royal fern can be sprayed but care is needed when using agrichemicals over water.
If manually removing plants, always take care contain the spores and remove all fragments of the plant – including the roots which can grow quite deep. Dispose of plant material in general waste. If foliar spraying, leave the plants to rot down.
Always follow up every 3-6 months or when you notice new growth.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and directions for the purchase, use and storage of the product, are followed and adhered to.
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