Pond apple

• This semi-deciduous tree is generally 3–6m tall but can grow up to 15m tall.
• Stems are softwood with thin, grey bark bearing prominent lenticels (pores that allow gas exchange).
• Leaves are alternate, 7–12cm long and light to dark green with a prominent midrib. When crushed, they emit a smell similar to green apples.
• Flowers are cream to pale yellow with a red inner-base, 3 leathery outer petals and 3 smaller inner petals. They are 2–3cm in diameter and short-lived.
• Fruit is green, spherical, 5–15cm in diameter and similar to the smooth-skinned custard apple.
• Each fruit contains 100–200 seeds similar to pumpkin seeds in size and shape.

3D model

• View the 3D model to help you identify this plant. You can magnify the image and manipulate the view to inspect the plant from every angle.

• Requires moist soil with regular inundations of fresh to brackish water.
• Prefers creeks, riverbanks, flood plains, wetlands, rainforest areas and agricultural drainage systems.

• Covers around 2,200ha of Queensland, with the main infestation in the Wet Tropics bioregion between Cardwell and Cooktown.
• Also found in small and/or isolated infestations in Brisbane, Nambour, Mackay, Townsville, Ingham, the east coast of Cape York, and Torres Strait Islands.
• Visit Weeds Australia and click on the distribution tab to view the distribution map.

• Flowers and produces fruit when at least 2 years old.
• Main flowering period is December–February, with fruit formation in January–March.
• Sporadic flowering and fruiting can also occur at other times.
• Fruit and seed can float and remain viable for many months in fresh to saline water; germination can occur in fresh or brackish situations.
• Seeds are relatively short-lived. In suitable conditions, seed banks can be rapidly depleted through mass germinations within 6 months of fruit fall.

Environmental

• Invades fresh, brackish and saltwater areas.
• Forms dense stands in swamp areas; thickets can replace ecosystems.
• Colonises undisturbed areas.
• Has greatest effect on melaleuca wetlands, Heritiera littoralis mangrove communities, riparian areas, drainage lines, coastal dunes and islands.

• Seeds and fruit are generally spread by water.
• Seeds are also spread by feral pigs, wallabies, cassowaries and other fruit-eating animals.

• Find out how farmers can prevent weed spread.
• Find out how gardeners and outdoor enthusiasts can prevent weed spread.

Physical control

• Hand-pull plants.
• Use fire if sufficient fuel is available. (Dense infestations often don't contain sufficient fuel.) Burn the entire circumference of a plant to kill it effectively. Depending on its intensity, fire can destroy seeds on the ground but seeds in cracks or on moist soil can remain viable.
• Control seedlings that germinate following fire.

Mechanical control

• Chain-pull or dozer-push plants, but only on flat country in areas free of sensitive vegetation, where machines can manoeuvre easily, and where erosion risk is low.
• Ensure that roots of uprooted trees are not in contact with soil, or plants may resprout.

Herbicide control

Stem injection method

• You can use this method in aquatic areas because it minimises herbicide run-off and off-target impacts.
• Do not use this method for larger trees because a large number of cuts/holes are required. Also, it is difficult to use for multi-stemmed trees, because each separate stem requires treatment.

Axe cut method

• Make horizontal cuts into sapwood around the circumference of the stem, as low as possible.
• While still in the cut, lean the axe out to make a downward-angled pocket and inject herbicide into it. Use a double row of cuts, with the second row under the spaces created by the first row, for maximum kill rate.

Drill and fill method

• Drill holes at a downward angle, 5cm apart around circumference, with a power drill. Immediately inject herbicide into the holes.

Cut stump treatment

• You can use this method for large trees and multi-stemmed plants.
• Cut the stem through horizontally, as close to ground as possible, and treat the cut surface immediately with herbicide.

Basal bark treatment

• Spray or paint herbicide and diesel mix around the stem circumference, from ground level up to 50cm.
• Do not use this treatment in aquatic situations—it has environmental consequences and is not effective.

Foliar spray

• Use foliar herbicides for dense monocultures of young plants up to 1m tall where there is no risk of damaging native vegetation.

Read the pond apple fact sheet to find out more about herbicide control and application rates.

Biological control

• There are no known biological control agents.

• Pond apple is a category 3 restricted invasive plant under the Biosecurity Act 2014. You must not:
  • give it away
  • sell it
  • release it into the environment.

  If you do any of these, penalties may apply.

• You must take all reasonable and practical measures under your control to minimise the biosecurity risks associated with dealing with pond apple. This is part of your general biosecurity obligation.
• Each local government agency must have a biosecurity plan that covers invasive plants in its area. This plan may include actions to be taken on pond apple. Some of these actions may be required under local laws. Contact your local government for more information.