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NQ DRY TROPICS WEED FREE
PRICKLY ACACIA
Vachellia nilotica
PRICKLEY ACACIA
TREES
DESCRIPTION
This umbrella shaped , perennial tree can grow from 4 to 10 metres . Young shrubs form dense thorny thickets , while mature trees are usually single stemmed , with spreading branches and have lost most of their thorns . Leaves are fern-like , with 4 to 10 pairs of leaf branches and 10 to 20 pairs of small , narrow , green leaves on each branch . Pairs of thorns grow at the base of the leaves . Flowers are golden yellow , ball shaped and 1 centimetre wide . They grow on stems from leaf joints with 2 to 6 flowers per group . It flowers in summer and autumn . Seed pods are 10 to 15 centimetres long , cylindrical with narrow constrictions between seeds ; they are grey when ripe . Habitat it grows in many soil types , particularly coastal clays , bore drains and watercourses . Weed characteristics can outcompete pasture for water and causes soil degradation . It alters natural grasslands into thorny scrub and thickets . Thorny thickets interfere with mustering , movement of stock and access to water . Dispersal of seed is via livestock and the seed takes up to six days to pass through the animal ’ s digestive system . Stock movement and transportation thus assists the further spread .
BIOSECURITY STATUS
Restricted . This species is Category 3 Restricted matter under Queensland Legislation . This species is also listed a Weed of National Significance ( WONS )
HOW TO ACT
Mechanical control is most cost effective for initial removal of dense infestations . Windrowing and burning to remove the debris will allow for regeneration of natural vegetation . Cut stump or basal barking is effective for isolated established plants . Young plants can be physically removed . Foliar spraying is effective when plant is actively growing . Control should be carried out prior to seed set with follow up monitoring and control of emergent growth important . Fire may be essential to stimulate the dormant seed bank so seedlings can then be controlled with herbicide .