Beautiful but Destructive

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

 

The Octopus Tree, Schefflera actinophylla also known as the Umbrella tree belongs to the family Araliaceae. It is native to tropical rainforests and gallery forests in eastern Queensland and the Northern Territory of Australia, New Guinea and Java.  

 

  

Umbrella Tree

 

The Octopus Tree Schefflera actinophylla is an evergreen tree growing to 15 m tall. It has compound medium green leaves in groups of seven leaves. It is usually multi-trunked, and the masses of bright red flowers develop at the top of the tree. It often grows as an epiphyte on other rainforest trees or as a lithophyte on rocky outcrops. The Octopus Tree produces up to 1000 individual flowers generating large amounts of nectar which attracts nectar-eating birds and insects. The thousands of fruits produced each containing many seeds are eaten by many birds in particular by Black Collard Barbets, seed dispersal is predominantly carried out by birds. 

 

Octopus tree is a most fitting name for this highly invasive and very destructive tree which with its octopus like roots is even able to grow on boulders, the octopus like roots are very invasive and destructive damaging, house foundations, buildings and blocking drains. Here in Durban one can very often see the Octopus tree growing as an epiphyte in particular high up on the roofs of buildings where it causes considerable structural damage to the building if not removed right away. It is a very aggressive plant and its roots dominate the surrounding soil. In many tropical and subtropical areas around the world it has become a very invasive and destructive weed, because of its rapid growth, its habit of forming dense stands, and its epiphytic nature make the octopus tree potentially detrimental not only to native plant communities but to buildings and other man made structures as well. The Octopus tree can cause contact dermatitis in sensitive individuals. 

 

Control  

The Octopus tree is very difficult to control once established on a large scale. Control of newly established, small, and young populations is probably easier than the control of well established, mature populations. The eradication of octopus trees with stem diameters greater than 25 cm is extremely difficult. 

 

Physical or mechanical control:Hand pulling of seedlings and young saplings is recommended. Cutting down of larger trees requires a follow-up treatment with a chemical herbicide to control re-growth and sprouts from the remaining roots. Freshly cut stumps 

must be treated as soon after cutting as possible preferably within 2 hours. 

 

Chemical control: The Octopus tree is very difficult to control with herbicides in addition the effects of herbicides may not be seen for months, and follow-up treatments will be necessary. When the octopus tree is growing as an epiphyte, herbicide applications require care to avoid harming the host plant. Those with experience controlling the octopus tree recommend cutting trees and treating the stumps with a herbicide. 

Herbicides containing the following active ingredients and at the dose rates suggested below have shown a measure of success. 

 

Method 

Active ingredient 

Dose rate 

Cut stump, or paint basal green bark 

Glyphosate(360 g/L) 

(Roundup) 

85 ml  per 1L water 

Drill, frill, axe or stem injection 

Glyphosate (360 g/L) 

(Roundup) 

500 ml per 1L water 

Apply 1 ml per 2 cm cut 

Basal bark application 

Triclopyr (240 g/L) 

(Garlon)  

Picloram (120 g/L) 

(Tordon) 

in equal proportions 

100 ml of mix per 6L diesel 

 

Conclusion 

The Octopus tree has become a very serious pest plant in many other countries with climates similar to our climate here in Durban. Looking at the rapid increase of these plants in only a few years it is certain that these trees very will soon present the same problems here in the Durban area, therefore it is the environmental and social responsibility of every landowner who has an Octopus tree growing on his or her property to remove it as soon as is possible and to encourage others to do likewise. This tree urgently needs to be listed as a category 1 weed in South Africa in this time of rapid climate change we can not afford to wait for the government to make this to happen we must act now to eradicate the Octopus tree before it is too late for it to be controlled. 

 

Michael Hickman 24.03.12