Syringa - Melia azedarach

This invasive alien species is present in the Mount Moreland Conservation area

 

Syringa is a deciduous tree in the mahogany familyMeliaceae, that is native to PakistanIndiaIndochinaSoutheast Asia and Australia.

Alien invader - Syringa - Melia azedarach  Alien invader - Syringa - Melia azedarach

 

The adult tree has a rounded crown and attains a height of 7-12 metres. The flowers are small and fragrant with five pale purple or lilac petals growing in clusters the, flowers are unattractive to bees and butterflies. 

The fruit is a drupe, marble-sized, light yellow at maturity, hanging on the tree all winter, and gradually becoming wrinkled and almost white. The leaves are up to 50 cm long, compound. 

The hard, 5-grooved seeds were widely used for making rosaries and other products requiring beads, before their replacement by modern plastics. 

 

Toxicity 

Leaves have been used as a natural insecticide to keep with stored food, but must not be eaten as they are highly poisonous. 

The fruits are also poisonous to humans if eaten. The first symptoms of poisoning appear a few hours after ingestion. They may include loss of appetite, vomiting, constipation or diarrhoea, bloody faeces, stomach pain, pulmonary congestion, cardiac arrest, rigidity, lack of coordination and general weakness. Death may take place after about 24 hours.  

 

Syringa Melia azedarach is a highly invasive alien plant 

Melia azedarach is a highly invasive alien plant which can invade disturbed and relatively undisturbed areas, and by doing so, it can decrease native biodiversity. Melia azedarach has numerous defences against insects and other plant pathogens, giving it a competitive advantage over many native species. This invasive plant can also successfully reproduce vegetatively from the roots, forming dense thickets. These characteristics contribute to it very successfully becoming established and negatively impacting on native populations of plants and animals. Melia azedarach has a high degree of reproductive vigour, a wide range of adaptability to different soil conditions, has numerous defences against pests and predators, and produces copious amounts of bird-dispersed seeds.  

 

Control measures 

The best and most cost effective method of control of Melia azedarach occurs with the use of chemical methods. 

 

Herbicides 

The control method of choice is a basal bark application of triclopyr (brand name Garlon®, and others). A 1.5 % solution of triclopyr mixed with diesel is highly effective when applied as a 20 cm band near the base of the trunk.  A foliar treatment using a 1% solution of triclopyr mixed with water provides good control of seedlings  and young plants, but high volumes of the solution must be applied. Basal bark treatment is only effective when the tree is actively growing preferably in the hot early summer months. 

 

Mechanical Control 

Because Melia azedarach has the ability to re-sprout from the cut stump as well as to send root and stem suckers from underground storage organs mechanical methods will be ineffective unless followed up with the application of a herbicide to the cut surface and stump. A 1.5 % solution of triclopyr mixed with diesel is highly effective in preventing regrowth if applied to the cambium layer between the bark and the inner woody trunk and in a band of around 100 mm around the entire stump. 

 

Michael Hickman 

14.04.12