Download PP02-Wild Ginger.indd - Bay of Plenty Regional Council

Sustainable
Options
Pest Plant Control
Wild Ginger (Hedychium gardnerianum and
Hedychium flavescens)
Introduction
There are two species of wild
ginger, kahili ginger (Hedychium
gardnerianum) and yellow ginger
(Hedychium flavescens). Both
species can form dense colonies
in native forests, smothering
young native plants as well
as preventing native seedling
establishment. This leads to
the alteration of the structure
of native forest and may result
in the total death of the forest.
Origin
Kahili ginger is a native of
India, growing on the lower
slopes of the Himalayas, while
yellow ginger originates in
eastern India and Madagascar.
Both gingers have been
cultivated in New Zealand
gardens since 1865, but it was
not until the 1940s that kahili
ginger was officially recorded
as growing wild.
Pest Plant Status
In the Bay of Plenty region
wild ginger is classified as a
Progressive Control Pest
Plant. (Refer Environment
Bay of Plenty’s Regional Pest
Management Strategy.)
Land occupiers are required
to control wild ginger on their
properties. Assistance may be
available from Environment
Bay of Plenty by way of approved
programmes. It is banned from
sale, propagation and distribution
within New Zealand.
Description
The wild gingers are herbaceous
perennial plants. This means
Kahili ginger has been a popular ornamental
garden plant
that their life-spans extend for
more than two years and they
do not accumulate woody tissue.
Wild ginger grows from large,
branching rhizomes. These large
bulbous roots produce vertical
stems annually. Beds of living
rhizomes can form a dense layer
up to a metre thick. Adult stems
reach a maximum height of two
metres and produce large wax
covered, ovate alternate leaves
(20 to 45 cm long and 10 to 15
cm wide). Yellow ginger leaves
tend to be a little narrower than
kahili ginger leaves.
Individual kahili ginger flowers are
lemon yellow with conspicuous
red stamens and are displayed in
large composite flower heads
(12 to 45 cm in length), from
February to April. Red seeds
(1.5 to 1.8 cm long) are produced
by kahili ginger during the autumn
and winter months, with more
than 100 seeds per flowerhead.
Seed production tends to
decrease as light levels decline
under the forest canopy.
Yellow ginger flowers are cream
to light yellow in colour and come
out in the late autumn/early winter
period. The flowers are displayed
in smaller composite flowerheads
Kahili ginger flower head
than those of kahili ginger.
Yellow ginger flowers do not
produce seed.
Invasion
Both wild gingers spread
outwards along the ground by
way of rhizomes, with new stems
sprouting annually. New plants
may develop also from rhizome
portions which have become
detached from the parent plant.
The major source of this spread
is by the illegal dumping of wild
ginger rhizomes on roadsides
or in bush. Kahili ginger is also
spread by birds, eating and
dispersing seeds away from the
original infestations.
Control Methods
Manual
Kahili ginger flowers can be cut
and dropped on the ground prior
to the seeds being formed. If
seeds are present put the flower
heads into a bag for disposal
Working with our communities for a better environment
02
Wild Ginger (Hedychium gardnerianum
Sustainable Options
Pest Plant Control
Yellow ginger flower head
A Kahili Ginger seedling in native bush
with the household rubbish.
Flowerhead removal will not kill
the plant but it will stop it seeding.
Digging is an effective method
of removing small stands of wild
ginger, providing all the roots are
removed intact and disposed of
safely at an authorised refuse
transfer station.
CAUTION: Be careful not to spray
desirable neighbouring plants.
Herbicide
•
Metsulfuron-methyl
(e.g. Escort®, Meturon®)
Knapsack:
5 grams / 10 litres water plus
10 ml penetrant (e.g. Pulse®)
Handgun:
25 grams / 100 litres water
plus 100 mls penetrant (e.g.
Pulse®)
There are two application methods
using the above herbicide:
1 Overall Spraying
Ensure complete coverage
of the plants. Wait until leaves
and stalks have browned
off (which may take several
months) before removing
them. This method is suitable
for large infestations.
02
Metsulfuron-methyl is active in
the soil and may be absorbed
by the roots of neighbouring
plants, possibly killing them.
2 Cutting and Spraying
Cut off the leaves and stems
and immediately spray the cut
stems and rhizomes.
This method means less
herbicide is used and there
is less chance of spray drift.
It is preferable to use this
method for smaller infestations
where ginger plants are close
to desirable plants or if the
ginger is very tall.
Information in this fact sheet
regarding herbicides does not
necessarily appear on the labels
of the products concerned.
Environment Bay of Plenty does
not accept liability for any damage
that may arise from use of
chemicals at non-standard rates.
Mention of product trade names
implies neither endorsement of
those products nor criticism of
similar products not mentioned.
Hedychium flavescens)
Escort® herbicide applied to recently cut
ginger rhizomes. Apply herbicide under low
pressure and avoid runoff into the soil
CAUTION: When using any
herbicide READ THE LABEL
thoroughly to ensure that
all instructions and safety
requirements are followed.
For further information and advice, contact
your local pest plant officer at Environment
Bay of Plenty:
Telephone: 0800 ENV BOP (368 267)
Facsimile: 0800 ENV FAX (368 329)
Pollution Hotline: 0800 73 83 93
Email: [email protected]
Website: www.envbop.govt.nz
Address: 5 Quay Street, P O Box 364,
Whakatane, New Zealand
This fact sheet was prepared by Environment
Bay of Plenty’s Pest Plant Section.
This factsheet was last updated March 2005
Working with our communities for a better environment