Yellow Bells (Tecoma stans) is an evergreen shrub or small tree which originates from Mexico and the southern United States. It is highly invasive in South Africa and thrives in coastal and Lowveld regions. It is listed under NEMBA as a Category 1b invasive plant. It was introduced to South Africa as an ornamental due to its striking yellow flowers and first recorded around 1858.
Yellow bells are very difficult to control. Mechanical control by hacking or felling the trees can cause further aggressive spreading through coppicing. They also produce prolific seeds which are spread by wind and water. There is concern that they could invade river courses in the Kruger National Park.
Biocontrol is possibly the best option in controlling this tree. A rust fungus (Prospodium transformans) was released in 2010 but has not established successfully. A leaf-feeding lady beetle (Mada polluta) has been more successful and was released in October 2013. Further biocontrol options are being investigated by the Agricultural Research Council.
This invader is prolific around Mbombela (Nelspruit), as well as other regions in the Lowveld.