Joburg’s shot-hole borer infestation not a disaster – yet

Johannesburg City Parks and Zoo said that it is too early to classify the outbreak of polyphagous shot-hole borer (PSHB) in Johannesburg as a disaster, reports Rosebank Killarney Gazette.

City Parks continues to meet with their counterparts for urban forestry in government, research institutions, tree maintenance service providers and internal teams to identify the extent of the infestation which has killed off a number of trees in Joburg.

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According to MMC for Community Development Nonhlanhla Sifumba, many parts of the world that are reporting PSHB infestations are yet to successfully implement a chemical application to contain the problem.

The shot-hole borer beetle starts to invade this tree from the lower trunk. Photo: Naidine Sibanda

City Parks is monitoring a phenomenon where some London planes along Jan Smuts Avenue in Saxonwold have developed an immune mechanism with trees showing positive signs of recuperation.

“While this is an exciting and positive break-through that hopefully signals the tail-end of the outbreak, we are also treading cautiously to ensure that we are guided by research findings to confirm that this outbreak is on its way out,” said Sifumba.

City Parks established a PSHB committee which has so far:

• Commissioned an internal research pilot project in Region B where shot-hole borer is most prevalent in order to map infested trees, assess the tree’s health and that of the urban canopy and test the efficacy of solarisation as a proposed intervention to treat and dispose of infested wood
• Closely monitor developments in other countries to note how the infestation is being managed
• Engage or establish working relationships with organisations
• Confirmed that no pesticides or chemicals have been approved by the Department of Agriculture, Forestry and Fisheries (DAFF) to control the beetle
• Commenced with the propagation of resistant trees at its Huddle Park Nursery as part of its tree replacement strategy

City Parks said that due to the lack of data, they are unable to classify the infestation as a disaster.

Sifumba said, “There are no known pesticides or chemical applications that have been approved for trials by DAFF.”Furthermore, residents with infested 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 infected by the borer beetle.”

Sifumba affirmed that diseased street trees, except for the box elders that are thriving, will also not be removed.

An open day will be hosted in March for all interested residents to identify and responsibly dispose of dead wood affected by PSHB.

Sifumba affirmed that City Parks will work with all bodies and concerned groups to tackle the infestation collectively in order to protect Joburg’s man-made forest.

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