Beetle threat to Cape trees
The polyphagous shot hole borer has invaded and damaged thousands of trees in other parts of the country and now experts think it could make its way to Cape Town and damage indigenous and exotic trees.
Professor Wilhelm De Beer of the University of Pretoria, who is part of a collaborative research team that is focused on the beetle, said drought-stressed trees such as the oak which are a permanent feature in towns such as Stellenbosch could be wiped out in the next 10 years.
“My prediction is that in the next five to 10 years Stellenbosch will look different. As is, the oak trees are not in a happy state because of the drought,” he said.
The City’s Recreation and Parks Department, together with the Invasive Species Unit, has an operational plan to deal with the borer, which is smaller than a sesame seed.
“The impact could be significant, especially considering that Cape Town’s trees are already stressed as a result of the drought,” said mayoral committee member for community services and health Zahid Badroodien.
Although the borer has not been detected in Cape Town yet, it has been found in George, Sedgefield and Wilderness.
Until two years ago, it was not heard of in South Africa until it was detected in Pietermaritzburg. Reports of its invasion have been confirmed in eight provinces, except Limpopo.
“It’s just a matter of time before it arrives in Cape Town”, said De Beer.
“Until now there had only been confirmed reports about it in Israel and California”, De Beer said.
The small insect, whose origin is Asia, is known to invade the host tree and bore holes in the branches and invade a variety of 80 species.
They dig tunnels to lay eggs and transport a fungus which attacks the tree’s vascular tissue. This in turn interrupts the supply of water and nutrients to the tree and could kill a tree. This includes oak, most willows, plane trees, avocado, some acacias and most maples - some of which are common in Cape Town.
The beetle has already caused damage to more than 10 000 trees in Johannesburg, Durban, Pietermaritzburg, George and Knysna.