'Pond apple' is hardly the most ominous sounding name for an invasive species, but the damage this tenacious tree can do if left to its own devices should not be underestimated. A tropical fruit tree hailing from Africa and the Americas, Annona glabra can be a tremendous scourge to landowners and farmers and can savagely impact native ecosystems. For these reasons and more, the pond apple has been placed on the Australian government's Weeds of National Significance list, and any pond apples you find growing on your property must be removed promptly and thoroughly.
What makes the pond apple such a pest?
Pond apples have a number of qualities that, while beneficial to the trees themselves, can be disastrous for you:
- Dense growth: Pond apples tend to grow together in tightly packed thickets. This starves native flora in the area by starving them of sunlight and nutrients and can lead to large areas of homogeneous pond apple growth.
- Adaptability: Pond apples can grow in a wide variety of habitats and can easily tolerate poor soils and large concentrations of soil salinity.
- Waterway obstruction: Despite the aforementioned adaptability of pond apples, they cannot grow in dry soil. As such, pond apples are generally found growing in wetlands, mangrove swamps and by rivers and streams. Aside from the ecological damage this can do to such sensitive habitats, thickets of pond apples can obstruct access to water for livestock and irrigation purposes and can clog drains and farm culverts.
- Rapid spread: Pond apple seeds float, allowing them to be carried many miles by the waterways they generally grow beside. They can also be spread by animals who consume the tree's edible fruits, and their tough outer shells allow them to remain viable for long periods.
How should I remove pond apples growing on my land?
As you can see, removing pond apples growing on your property is in your best interests, and there are several ways to go about it:
- Burning: Thickets of pond apples can be burned, as long as they are suitably isolated from other native flora and fauna. However, the moist nature of the habitats in which pond apples grow means that thorough burning can be difficult, so this is an option best used for tackling small thickets during summer months. Be sure to thoroughly scour the soil for seeds once burning is complete.
- Uprooting: Having pond apple trees bulldozed or uprooted with chain pulling is another viable option, but only if the area remains accessible to heavy equipment. Hiring a professional tree management firm to remove trees is your best bet, especially when they are located in awkward, dangerous places such as sloped riverbanks. Manual uprooting with shovels and picks takes more time, but is an easier option for tackling trees in swamps and wetlands.
- Herbicides: Herbicides rated for use against woody-stemmed weeds are generally effective against pond apples. However, administering herbicides without damaging other plants can be difficult, especially in moist areas where runoff can easily contaminate groundwater. Have your herbicides injected directly into the stems of the offending trees to minimise this risk.