The Problem

In 2017, the Polyphagous Shot Hole Borer (euwallacea fornicatus) was detected on London Plane trees in the KwaZulu-Natal National Botanical Gardens in Pietermaritzburg. Native to Southeast Asia, this beetle has a symbiotic relationship with the fungus (Fusarium Euwallaceae) which serves as a food source for the adults and their larvae.

The beetles can attack a wide range of living exotic and indigenous trees. In susceptible trees the fungus slowly kills the tree. First, the tree’s vascular system begins to fail, leaves begin to thin on the ends of the branches, eventually turning brown, leading to the branch and eventually the tree dying.

The PSHB infestation in South Africa has reached Johannesburg, Durban, Richard’s Bay, Pietermaritzburg, George, Knysna and Hartswater. Johannesburg, with its dense urban forest, has been hit particularly hard.

Currently, no chemical products are registered for use against the PSHB. There is no single solution, and a successful treatment and prevention regime will have to incorporate multiple strategies, treatments and products.

The Polyphagous Shot Hole Borer beetle enter the trees through the bark. They create branching, breeding and feeding galleries lined with a layer of spores of the fungus they carry, which serves as food to both the beetle and larvae. The males are generally lighter in colour and smaller than females.

Here’s what they look like:

Polyphagous Shot Hole Borer - PSHB.co.za

beetle identification

beetle identification

The Tree Survey mobile app allows you to report infestations. Each reported incident receives in-app feedback. You can just report the bug, or you can select a further action from either a City Parks official or a private service provider.

We’ve put together a few relevant videos to give you some of the history around community action and investigative journalism pieces into the PSHB infestation.