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Durban Early Detection and Rapid Response

Port Jackson Willow Acacia saligna

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Common Name
Port Jackson Willow
Classification
CARA Category 1
NEMBA 1b

A member of the Fabaceae family originating from southwest Australia, this tree/shrub has a short trunk and a weeping habit. It grows up to eight metres tall. Like many acacia species, it has phyllodes rather than true leaves, which can grow up to 25cm in length. At the base of each phyllode is a nectar gland, which secretes a sugary fluid. This attracts ants which are responsible for distributing the seeds for further germination. The fruit is a legume, while the seed is oblong and dark black in colour. Acacia saligna has yellow flowers that appear between August and November.

Flowers
Why is it a problem?
It competes with, and has the potential to replace, indigenous species.
Control method
The Port Jackson Willow can be eradicated by means of mechanical, chemical and biological control. Mechanical techniques include ringbarking, as well as cutting the plants off at ground level and then applying herbicide (a chemical control). The most effective form of eradication however, is the biological control agent. The gall-forming rust fungus, Uromycladium tepperianum, has proven to be highly effective at reducing population densities by up to 80%. The acacia seed weevil, Melanterius spp, was introduced in 2001 and it is hoped that it will reduce the seed production to a level where there is not enough available for stands to regenerate at a high density after fires.
Where is it a problem?
It is found in KZN and the Western and Eastern Cape provinces.

Identifying other species

For help with identifying other species, submit your photo and observations to
iSpot: www.ispot.org.za

The iSpot experts may be able to provide a name.

 

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