TUBER LADDER FERN
Nephrolepis cordifolia
DESCRIPTION
This species is also called tuber sword-fern, tuber fern, Chinese fern, and ‘that mongrel fern’, depending on where you live and how much of it you’ve got. If you live in Northland, you’ll probably be favouring the ‘mongrel fern’ moniker.
It’s originally a popular pot plant or a garden fern, and in cool locations it does produce a very attractive ground cover, at least to begin with.
However, the tuber ladder fern has a dark side, because it spreads via a network of rhizomes on creeping runners that spread widely from the parent plant. These runners normally have lots of potato-shaped tubers attached to the roots, and it is these tubers that create the control problem, as we will see below.
Once established outside the garden, the tuber ladder fern becomes a wildly invasive species that forms a large, dense mat of vegetation, crowding out all other species, and providing a habitat for pest animals like rats.
The plant has long, erect leaves or fronds that grow to over a metre in length. These are feather-like in appearance, with up to 50 pairs of leaflets, appearing rather like the rungs of a ladder. Hence, presumably, the name ladder fern.
These frond-like leaves nurture, on their back surfaces, small organs called sori, that are actually a cluster of spores. The spores are yet another way the species spreads so readily. It combines spores, tubers and creeping runners, which add up to a bit of a spreading nightmare.
HABITAT
Often found around run-down garden sites, but regularly found spreading to track sides, bush margins, waste areas and stream banks. It’s very common in Northland, where it is subject to Pest Plant Management Strategies.
MANUAL CONTROL
It is fairly easy to pull out by hand, as long as the invasion hasn’t become too large for hand pulling to be impractical. But the entire plant, including all the tubers, must be removed, and allowed to rot down before burning or burying, or disposal at an appropriate rubbish transfer site. Do not dispose of freshly-pulled material at such sites where any plant material is recycled or composted.
HERBICIDES TO CONTROL TUBER LADDER FERN
There is only one reliable herbicide for controlling and eradicating tuber ladder fern; metsulfuron-methyl (MSF600).
Weed Wiping Herbicides to Kill Tuber Ladder Fern Weed
In pasture, where terrain permits, weed wiping is a very good control method, as it does no pasture damage.
- 2g MSF600 per litre of water in a towed weed wiper. Follow-up treatment by the same method will be necessary.
Spray Herbicides to Kill Tuber Ladder Fern
- 1g MSF600 per 10L of water, sprayed by knapsack or handgun. Spray all foliage to the point of visible dampness. Add 10ml of SuperWetter penetrant per 10L of water.
IMPORTANT!
After spraying, you MUST leave the sprayed site undisturbed for 3-4 months (don’t clear it, mow it or replant it), to allow the metsulfuron-methyl sufficient time to penetrate right through the plant to the tubers, where it will then prevent the formation of any new growth.
