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General information
Pond apple is a native of tropical North, Central and South America and West Africa where it occurs in fresh and brackish swamplands. In 1912, pond apple was introduced to Australia as grafting stock for commercially grown custard apple.
In its native America, pond apple fruit has some commercial use. The wood and roots are very light, and are used as a substitute for cork floats.
Pond apple is a declared Class 2 pest plant under Queensland legislation and a Weed of National Significance (WONS).
Scientific name | Annona glabra |
Description |
- Semi-deciduous tree that grows to 3 to 6m in height and can reach up to 15m.
- Softwood stems with a thin grey bark bearing prominent lenticels (pores that allow gas exchange)
- Leaves are alternate, 7 to 12cm long with a prominent midrib.
- Leaves vary from light to dark green.
- When crushed, leaves emit a distinct smell similar to green apples.
- Flowers are pale yellow to cream with red inner-base that consist of three leathery outer petals and three smaller inner petals.
- Flowers are short-lived, rarely noticed and 2 to 3cm in diameter.
- Green spherical fruit about 5 to 15cm in diameter, which looks like a smooth-skinned custard apple.
- Each fruit contains 100 to 200 seeds of similar size and shape to pumpkin seed.
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Habitat |
- Requires moist soil with regular inundations of fresh to brackish water.
- Prefers creeks, riverbanks, floodplains, wetlands, rainforest areas and agricultural drainage systems.
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Distribution |
- Native of tropical North, Central and South America.
- Covers around 2200ha of Queensland, with the main infestation in the Wet Tropics bioregion between Cardwell and Cooktown.
- Small and/or isolated infestations are found in Brisbane, Nambour, Mackay, Townsville, Ingham, the east coast of Cape York and the Torres Strait Islands.
- An infestation was discovered south of Darwin in late 2010.
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Life cycle |
- Flowers and produces fruit when at least two years old.
- Main flowering period in the Wet Tropics is from December to February with fruit formation following in January to March.
- Sporadic flowering and fruiting can also occur at other times of the year.
- Both fruit and seed can float and remain viable for many months in fresh to saline water and germination can occur in fresh or brackish situations.
- Seeds are relatively short-lived and when conditions are suitable, seed banks can be rapidly depleted through mass germinations within six months of fruit fall.
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Spread | Generally spread by water, seed can also be disseminated by feral pigs, wallabies, cassowaries and other fruit-eating animals. |
Impacts |
Environmental:
- Invades fresh, brackish and saltwater areas.
- Forms dense stands in swamp areas, thickets capable of replacing ecosystems.
- Ability to colonise undisturbed areas.
- Melaleuca wetlands, Heritiera littoralis mangrove communities, riparian areas, drainage lines, coastal dunes and islands are most at risk.
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Prevention |
The best form of weed control is prevention. Treat weed infestations when they are small. Do not allow weeds to establish.
Steps for weed prevention:
- Check your property regularly for suspect plants.
- Control new infestations before they spread and become a major problem.
- Don't dump weeds and garden waste in bush or parkland.
- Know the weed status of any products or materials you are receiving. This includes fodder, grain, gravel, machinery, mulch, packing material, sand, soil, stock, vehicles and water.
- Clean your equipment, clothing, shoes, vehicles and machinery when leaving natural habitats and camping areas.
- Use a cleandown facility to blow, vacuum or wash dirt and seeds from vehicles, machinery and tools.
- Request a weed hygiene declaration from your suppliers.
- Ensure vehicles and machinery are clean before entering your property.
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Physical control |
Hand-pulling is effective.
Fire:
- Sufficient fuel is required for control using fire. Unfortunately this is not often available in dense pond apple infestations.
- Entire circumference of the plant must be burnt to kill effectively. Depending on its intensity, a fire can destroy seeds lying on the ground but seeds in cracks or on moist soil where fire will not burn can remain viable.
- Follow-up work is required to control seedlings that germinate following fire.
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Mechanical control |
- Options include chain pulling and dozer pushing.
- These methods (except hand pulling) are only suitable on flat country; in areas free of sensitive vegetation; where machines can manoeuvre easily; and where the risk of soil erosion is low.
- Ensure that the roots of uprooted trees are not in contact with soil or else plants may resprout.
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Herbicide control |
Stem injection:
- Recommended for aquatic areas as it minimises herbicide run-off and off-target impacts.
- Stem injection is not generally suited to larger trees due to the number of cuts/holes required. It is also difficult to control multi-stemmed trees where each separate stem requires treatment.
Axe cut method:
- Make horizontal cuts into the sapwood around the circumference of the stem, as low to the ground as possible.
- While still in the cut, lean the axe out to make a downward angled pocket in which herbicide is injected. A double row of cuts, with the second row placed under the spaces created by the first row, is recommended for maximum kill rate.
'Drill and fill method':
- Drill downward angled holes, 5cm apart around the circumference, with a powered drill. Herbicide is then immediately injected into the holes.
Cut stump:
- Suitable for use on large trees and multi-stemmed plants.
- Cut stem through horizontally, as close to the ground as possible, and the cut surface is treated immediately with herbicide.
Basal bark:
- Spray or paint herbicide and diesel mix around the circumference of the stem, from ground level up to 50cm.
- Do not use in aquatic situations for both environmental and effectiveness reasons.
Foliar application:
- Herbicides are useful for dense monocultures of young plants up to 1m tall where there is no risk of damaging native vegetation.
- See the pond apple fact sheet (PDF, 218 KB) for herbicide control and application rates.
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Biological control | There is no biological control agent available for pond apple. |
Declaration details |
- A declared Class 2 species under the Land Protection (Pest and Stock Route Management) Act 2002.
- Taking for commercial use, introduction, keeping, releasing and supplying (including supplying things containing reproductive material of this pest) is prohibited without a permit issued by Biosecurity Queensland.
- Landholders are required to control declared pests on their properties.
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Further information
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