South Africa 14.7.2018 06:35 am

Tree-killing beetles now target Bedfordview

A tree infected by the polyphagous shot hole borer. Picture: Supplied

A tree infected by the polyphagous shot hole borer. Picture: Supplied

The destructive polyphagous shot hole borer, which can affect an estimated 10 million of Joburg’s trees, has for the first time been seen in Ekurhuleni.

The residents of Ekurhuleni have been warned about a poisonous beetle that attacks a specific but wide range of tree species, including exotic trees.

The City said all hands are on the deck to fight the destructive polyphagous shot hole borer (PSHB) which had been identified in Bedfordview. It’s location has sparked fears that unless the insects were controlled early, a swarm of them could move around and attack trees in a wide area.

But early this year the borer was identified in other parts of Johannesburg. At the time it was reported it could affect some 10 million trees of which about six million were street and park trees.

It sent officials from the Johannesburg City Parks and Zoo (JCPZ) scouting about and attending to numerous complaints from concerned residents who needed action about the outbreak of the PSHB. At the time areas most affected by diseased trees in private properties were Hurlingham, Craighall Park, Dunkeld, Sandton, Parkview, Kensington and Houghton.

But so far in Ekurhuleni, Bedfordview has been identified. It is not clear how they came to the place as authorities are yet to release the full information about their habits and origin, but many residents believe they came from the Johannesburg side.

DNA samples of the polyphagous beetle and the associated Fusarium euwallaceae fungus, taken from a row of trees in Bedfordview, came back positive from the laboratory.

The PSHB is an invasive pest originally from Asia containing the fungal symbiont fusarium euwallaceae. The beetle (PSHB) derives its name from the mark it leaves on the bark of a tree, which resembled a shot gun bullet hole. The trees it infests often die from the poison it injects into the tree.

The name “polyphagous” means it eats many food host species. This beetle targets a wide range of tree species, both exotic and indigenous,” said a statement issued by the City and posted on its website yesterday.

The City said its effective method to eradicate the spread of the infection was to cut down infested trees hosting the beetle‚ and to dispose of them in a controlled manner‚ by first cutting them and then burning them. “Specialists have confirmed that there is no direct link to human health other than the loss of the trees to the environment, and the benefits associated with having a green environment,” the City said.

Residents can also identify an infected tree by the marks on the bark resembling shot gun bullet holes and discoloration. Identified vulnerable trees included avocado, macadamia nut, pecan, peach, orange and grapevine trees.

According to the City, many exotic tree species planted for ornamental purposes were also susceptible, including species of maple, holly, wisteria, oak and camellia.

It is also believed from tests conducted that if a tree has been killed by the beetle carrying and producing the fungus, and the tree is chopped and removed at ground level, the beetle could still survive in the stump left over in the ground for an unknown period, and may simply target any new tree of certain species that are planted nearby in the near future,” the City said.

ericn@citizen.co.za

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