Borer meets its match
Joburg City Parks and Zoo (JCPZ), the custodians of the City of Joburg’s street trees, has come up with a plan of action for the outbreak of the infestation of the polyphagous shot hole borer – which carries fungal spores that infects and kill trees.
While new sightings of the outbreak continue to be reported, some London planes along Jan Smuts Avenue in Saxonwold have developed a fighting back mechanism as wounds are showing positive signs of the tree recuperating from the infestation.
Mayoral committee member for community development Nonhlanhla Sifumba said “while this is an exciting and positive breakthrough that hopefully signals the tail end of the outbreak, we are also treading cautiously and are guided by research to confirm this outbreak is on its way out”.
JCPZ is working closely with institutions such as the Forestry and Agricultural Biotechnology Institute to survey the extent of the infestation. JCPZ is also referring all offers of assistance with chemical solutions to the department of agriculture and forestry to ensure there is a high level of compliance when it comes to chemical control interventions.
“There are no known pesticides that have been approved for trials by the department,” Sifumba said. “Furthermore, residents with infected trees on their property are urged not to remove a tree if it is not dead, unless it is the box elder tree, as it is known to be heavily susceptible to being affected.”
The shot hole borer is a minute beetle that embeds its larvae in the inner layers of the tree.
The larvae, once matured, then makes their way out of the tree by tunneling holes. The lesions on the trees may vary to resemble “pinheads” or a series of “gunshots” that stifle the flow of nutrients through the veins of a tree, resulting in a tree that is visibly diseased from the top.
This kills the tree and can destroy adjacent trees once the young beetles start to nest.
Diseased street trees, except box elders that are thriving, will also not be removed. Residents felling a dead tree that is infested are cautioned to dispose of the dead branches in a responsible manner on their private property by covering it with a tarp and to refrain from illegally dumping the dead wood.
The heat under the cover of the tarp will result in the death of the borers and the wood can then be recycled or used.